levonorgestrel oral/ethinyl estradiol (Rx)

Contraception

Monophasic

• 1 active tablet PO daily for 21 days, then 1 inert tablet PO daily for 7 days (follow manufacturer's color-coding for sequence)

91-day

• 1 combination tablet daily for 84 days, then either 1 inert tablet or 1 tablet of ethinyl estradiol 10 mcg for 7 days
• First cycle begins on first Sunday after onset of menstruation; if menstruation begins on Sunday, first combination tablet is taken that day, with subsequent tablets taken in order specified on dispenser
• Use nonhormonal backup method of contraception (eg, condoms and spermicide) for first 7 days of treatment
• Next and all subsequent 91-day courses of tablets are initiated without interruption on same day of the week (Sunday), following same schedule, with tablets taken at same time of day on each day of active treatment

Triphasic

• Regimens vary; see package inserts (follow manufacturer's color-coding for sequence)

Continuous cycle

• 1 tablet PO daily at same time each day, with no tablet-free interval

Missed Active Contraceptive Dose

One active tablet missed

• Take 1 tablet as soon as possible, or take 2 tablets on following day
• Alternatively, take 1 tablet, discard missed tablet, and continue taking subsequent tablets as scheduled
• Use other forms of contraception for next 7 days after missed dose or until menses occur

Two active tablets missed consecutively

• Take 2 tablets as soon as remembered and continue taking as scheduled
• Alternatively, take 2 tablets daily for the next 2 days and continue taking as scheduled
• Missed 3rd week of cycle and patient is Sunday Starter: Take 1 pill every day until Sunday; discard rest of pack, and start new pack that same day
• Missed 3rd week of cycle and patient is day-1 starter: Discard rest of pack, and start new pack that same day
• Use other forms of contraception for next 7 days after missed dose or until menses occur
• Menses may not occur this month; if menses do not occur for 2 consecutive months, contact healthcare provider about possibility of pregnancy

Three active tablets missed consecutively

• Sunday starter: Take 1 pill every day until Sunday; discard rest of pack, and start new pack that same day
• Day-1 starter: Discard rest of pack, and start new pack that same day
• Use other forms of contraception for next 7 days after missed dose or until menses occur
• Menses may not occur this month; if menses do not occur for 2 consecutive months, contact healthcare provider about possibility of pregnancy

Dosing Considerations

Post pregnancy

• Increased risk of venous thromboembolism (VTE) after delivery with combined hormonal contraceptives; risk declines rapidly after 21 days but does not return to normal until 42 days after delivery
• Centers for Disease Control and Prevention (CDC) guidelines recommend waiting 3-6 weeks to initiate oral contraception in postpartum women without additional VTE risks
• After vaginal birth: Wait ≥3 weeks before initiating oral contraception
• After cesarean section birth: Wait ≥6 weeks before initiating oral contraception
• Women with other risk factors for VTE in addition to postpartum: Do not use combined hormonal contraceptives
• Presence of other VTE risk factors in addition to postpartum status: Do not use combined hormonal contraceptives

Dosing Modifications

Renal impairment: Use with caution

Hepatic impairment: Do not administer

Safety and efficacy are expected to be the same in postpubertal adolescents aged <16 years and users aged >16 years

Use before menarche is not indicated

Contraindicated (3)

• fezolinetant

  ethinylestradiol will increase the level or effect of fezolinetant by affecting hepatic enzyme CYP1A2 metabolism. Contraindicated. Fezolinetant AUC and peak plasma concentration are increased if coadministered with drugs that are weak, moderate, or strong CYP1A2 inhibitors

• ombitasvir/paritaprevir/ritonavir & dasabuvir (DSC)

  ombitasvir/paritaprevir/ritonavir & dasabuvir (DSC), ethinylestradiol. unspecified interaction mechanism. Contraindicated. Potential for increased ALT; contraceptive failure may occur when coadministered with protease inhibitors (ritonavir).
  
  ethinylestradiol, ombitasvir/paritaprevir/ritonavir & dasabuvir (DSC). Either increases toxicity of the other by unspecified interaction mechanism. Contraindicated. ALT elevations >5 x ULN (including some >20 x ULN) observed in clinical trials when ethinyl estradiol was coadministered with ombitasvir/paritaprevir/ritonavir, with or without dasabuvir. Discontinue ethinyl estradiol-containing medications before initiating ombitasvir/paritaprevir/ritonavir, and/or dasabuvir. Restart ethinyl estradiol containing medication ~2 weeks after hepatitis C combination drug regimen completed.

• tranexamic acid oral

  tranexamic acid oral, ethinylestradiol. Either increases toxicity of the other by pharmacodynamic synergism. Contraindicated. Coadministration of tranexamic acid oral and combination hormonal contraceptives increases thrombotic risk.

Serious - Use Alternative (83)

• amobarbital

  amobarbital will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• anastrozole

  ethinylestradiol decreases effects of anastrozole by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Anastrozole should not be given concurrently with any estrogens or estrogen-containing products.

• antithrombin alfa

  levonorgestrel oral, antithrombin alfa. Either decreases effects of the other by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Risk of thromboembolic disorders.

• antithrombin III

  levonorgestrel oral, antithrombin III. Either decreases effects of the other by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Risk of thromboembolic disorders.

• apalutamide

  apalutamide will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of apalutamide, a strong CYP3A4 inducer, with drugs that are CYP3A4 substrates can result in lower exposure to these medications. Avoid or substitute another drug for these medications when possible. Evaluate for loss of therapeutic effect if medication must be coadministered. Adjust dose according to prescribing information if needed.
  
  apalutamide will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of apalutamide, a strong CYP3A4 inducer, with drugs that are CYP3A4 substrates can result in lower exposure to these medications. Avoid or substitute another drug for these medications when possible. Evaluate for loss of therapeutic effect if medication must be coadministered. Adjust dose according to prescribing information if needed.

• argatroban

  levonorgestrel oral, argatroban. Either decreases effects of the other by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Risk of thromboembolic disorders.

• armodafinil

  armodafinil will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• atazanavir

  atazanavir, ethinylestradiol. Other (see comment). Avoid or Use Alternate Drug. Comment: Significant changes (increase or decrease) can occur in estrogen plasma levels. Efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended. .

• belzutifan

  belzutifan will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of belzutifan with hormonal contraceptives may lead to contraceptive failure or increased breakthrough bleeding. Advise females of reproductive potential to use effective nonhormonal contraception. Based on animal studies, belzutifan can cause fetal harm.
  
  belzutifan will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of belzutifan with hormonal contraceptives may lead to contraceptive failure or increased breakthrough bleeding. Advise females of reproductive potential to use effective nonhormonal contraception. Based on animal studies, belzutifan can cause fetal harm.

• bemiparin

  levonorgestrel oral, bemiparin. Either decreases effects of the other by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Risk of thromboembolic disorders.

• bosentan

  bosentan will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• bivalirudin

  levonorgestrel oral, bivalirudin. Either decreases effects of the other by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Risk of thromboembolic disorders.

• brigatinib

  brigatinib will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Brigatinib induces CYP3A4 in vitro. Coadministration of hormonal contraceptives with brigatinib can result in decreased concentrations and loss of efficacy. Brigatinib can cause fetal harm. Women should use an effective nonhormonal method of contraception during treatment and for at least 4 months after the last brigatinib dose.
  
  brigatinib will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Brigatinib induces CYP3A4 in vitro. Coadministration of hormonal contraceptives with brigatinib can result in decreased concentrations and loss of efficacy. Brigatinib can cause fetal harm. Women should use an effective nonhormonal method of contraception during treatment and for at least 4 months after the last brigatinib dose.

• butabarbital

  butabarbital will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• calaspargase pegol

  calaspargase pegol, levonorgestrel oral. unknown mechanism. Avoid or Use Alternate Drug. Due to the potential for an indirect interaction between calaspargase pegol and oral contraceptives, concomitant use of these drugs is not recommended. Use another non-oral contraceptive method for females of childbearing potential.

• calaspargase pegol

  calaspargase pegol, ethinylestradiol. unknown mechanism. Avoid or Use Alternate Drug. Due to the potential for an indirect interaction between calaspargase pegol and oral contraceptives, concomitant use of these drugs is not recommended. Use another non-oral contraceptive method for females of childbearing potential.

• carbamazepine

  ethinylestradiol will increase the level or effect of carbamazepine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.
  
  carbamazepine will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• conivaptan

  conivaptan will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• dalteparin

  levonorgestrel oral, dalteparin. Either decreases effects of the other by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Risk of thromboembolic disorders.

• dexamethasone

  dexamethasone will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• efavirenz

  efavirenz will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• elagolix

  levonorgestrel oral decreases effects of elagolix by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Based on the mechanism of action of elagolix, estrogen-containing contraceptives are expected to reduce elagolix efficacy. Effects of progestin-only contraceptives on the efficacy of elagolix is unknown. Advise women to use nonhormonal contraceptives during treatment with elagolix and for 1 week after discontinuing elagolix.
  
  ethinylestradiol decreases effects of elagolix by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Based on the mechanism of action of elagolix, estrogen-containing contraceptives are expected to reduce elagolix efficacy. Effects of progestin-only contraceptives on the efficacy of elagolix is unknown. Advise women to use nonhormonal contraceptives during treatment with elagolix and for 1 week after discontinuing elagolix.

• elvitegravir

  elvitegravir will decrease the level or effect of ethinylestradiol by unknown mechanism. Avoid or Use Alternate Drug. Consider alternative nonhormonal methods of contraception to add or replace combination oral contraceptive

• enoxaparin

  levonorgestrel oral, enoxaparin. Either decreases effects of the other by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Risk of thromboembolic disorders.

• encorafenib

  encorafenib will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of encorafenib with hormonal contraceptives (CYP3A4 substrates) can result in decreased concentrations and loss of hormonal contraceptive efficacy. Since encorafenib can cause fetal harm, advise women of childbearing potential to use a highly effective nonhormonal contraceptive during treatment and for 2 weeks after final encorafenib dose.

• enoxaparin

  ethinylestradiol decreases effects of enoxaparin by pharmacodynamic antagonism. Contraindicated. Risk of thromboembolic disorders.

• enzalutamide

  enzalutamide will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• eslicarbazepine acetate

  eslicarbazepine acetate will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Use additional or alternative nonhormonal birth control.
  
  eslicarbazepine acetate will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Use additional or alternative nonhormonal birth control.

• exemestane

  ethinylestradiol decreases effects of exemestane by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Exemestane should not be given concurrently with any estrogens or estrogen-containing products.

• fexinidazole

  fexinidazole will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Fexinidazole inhibits CYP3A4. Coadministration may increase risk for adverse effects of CYP3A4 substrates.

• fedratinib

  ethinylestradiol will increase the level or effect of fedratinib by Other (see comment). Avoid or Use Alternate Drug. Avoid coadministration of fedratinib (a CYP3A4 and CYP2C19 substrate) with dual CYP3A4 and CYP2C19 inhibitor. Effect of coadministration of a dual CYP3A4 and CYP2C19 inhibitor with fedratinib has not been studied.

• fexinidazole

  fexinidazole will increase the level or effect of ethinylestradiol by affecting hepatic enzyme CYP2E1 metabolism. Avoid or Use Alternate Drug. Fexinidazole inhibits CYP3A4. Coadministration may increase risk for adverse effects of CYP3A4 substrates.

• fondaparinux

  levonorgestrel oral, fondaparinux. Either decreases effects of the other by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Risk of thromboembolic disorders.

• fosamprenavir

  fosamprenavir, ethinylestradiol. unspecified interaction mechanism. Avoid or Use Alternate Drug. Coadministration may decrease amprenavir AUC, and may lead to loss of virologic response. Coadministration of fosamprenavir with ethinyl estradiol may alter hormone levels. Alternative methods of nonhormonal contraception are recommended.

• griseofulvin

  griseofulvin will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• heparin

  levonorgestrel oral, heparin. Either decreases effects of the other by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Risk of thromboembolic disorders.
  
  ethinylestradiol decreases effects of heparin by pharmacodynamic antagonism. Contraindicated. Risk of thromboembolic disorders.

• idelalisib

  idelalisib will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Idelalisib is a strong CYP3A inhibitor; avoid coadministration with sensitive CYP3A substrates
  
  idelalisib will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Idelalisib is a strong CYP3A inhibitor; avoid coadministration with sensitive CYP3A substrates

• indinavir

  indinavir, ethinylestradiol. Other (see comment). Avoid or Use Alternate Drug. Comment: Significant changes (increase or decrease) can occur in estrogen plasma levels. Efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended. .

• isavuconazonium sulfate

  isavuconazonium sulfate will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• isavuconazonium sulfate

  isavuconazonium sulfate will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• ivosidenib

  ivosidenib will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of sensitive CYP3A4 substrates with ivosidenib or replace with alternate therapies. If coadministration is unavoidable, monitor patients for loss of therapeutic effect of these drugs.

• leniolisib

  leniolisib will increase the level or effect of ethinylestradiol by Other (see comment). Avoid or Use Alternate Drug. Leniolisib, a BCRP inhibitor, may increase systemic exposure of BCRP substrates

• lesinurad

  lesinurad decreases effects of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Use additional methods of nonhormonal contraception. Do not rely on hormonal contraception alone when taking lesinurad.
  
  lesinurad decreases effects of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Use additional methods of nonhormonal contraception. Do not rely on hormonal contraception alone when taking lesinurad.

• letrozole

  ethinylestradiol decreases effects of letrozole by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Letrozole should not be given concurrently with any estrogens or estrogen-containing products.

• lorlatinib

  lorlatinib will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• lonafarnib

  ethinylestradiol will increase the level or effect of lonafarnib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of lonafarnib (a sensitive CYP3A substrate) with weak CYP3A inhibitors is unavoidable, reduce to, or continue lonafarnib at starting dose. Closely monitor for arrhythmias and events (eg, syncope, heart palpitations) since lonafarnib effect on QT interval is unknown.

• lopinavir

  lopinavir, ethinylestradiol. Other (see comment). Avoid or Use Alternate Drug. Comment: Significant changes (increase or decrease) can occur in estrogen plasma levels. Efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended. .
  
  lopinavir will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• lumacaftor/ivacaftor

  lumacaftor/ivacaftor will decrease the level or effect of ethinylestradiol by unspecified interaction mechanism. Avoid or Use Alternate Drug. Avoid coadministration unless benefit outweighs risk. When coadministered, hormonal contraceptives are not a reliable method of effective birth control. Concomitant use may increase incidence of menstruation associated adverse effects (amenorrhea, dysmenorrhea, menorrhagia).

• mavacamten

  mavacamten will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Progestin and ethinyl estradiol are CYP3A4 substrates. Mavacamten may decrease systemic exposures of ethinyl estradiol and progestin, which may lead to contraceptive failure or an increase in breakthrough bleeding. Advise patients to use a contraceptive method that is not affected by CYP450 enzyme induction (eg, intrauterine system) or add nonhormonal contraception (eg, condoms) during coadministration and for 4 months after last mavacamten dose.
  
  mavacamten will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Progestin and ethinyl estradiol are CYP3A4 substrates. Mavacamten may decrease systemic exposures of ethinyl estradiol and progestin, which may lead to contraceptive failure or an increase in breakthrough bleeding. Advise patients to use a contraceptive method that is not affected by CYP450 enzyme induction (eg, intrauterine system) or add nonhormonal contraception (eg, condoms) during coadministration and for 4 months after last mavacamten dose.

• metyrapone

  ethinylestradiol decreases effects of metyrapone by unspecified interaction mechanism. Avoid or Use Alternate Drug. A subtherapeutic response to metyrapone can be seen in patients on estrogens, including oral contraceptives, that contain estrogen therapy. It may be advisable to discontinue estrogens prior to and during metyrapone administration.

• mifepristone

  mifepristone will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.

• mifepristone

  mifepristone will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• mobocertinib

  mobocertinib will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of mobocertinib with hormonal contraceptives may lead to contraceptive failure or increased breakthrough bleeding. Advise females of reproductive potential to use effective non-hormonal contraception.
  
  mobocertinib will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of mobocertinib with hormonal contraceptives may lead to contraceptive failure or increased breakthrough bleeding. Advise females of reproductive potential to use effective non-hormonal contraception.

• mycophenolate

  mycophenolate decreases effects of ethinylestradiol by unknown mechanism. Avoid or Use Alternate Drug. Patients should consider using an alternative or additional form of contraception.

• nefazodone

  nefazodone will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• nelfinavir

  nelfinavir, ethinylestradiol. Other (see comment). Avoid or Use Alternate Drug. Comment: Significant changes (increase or decrease) can occur in estrogen plasma levels. Efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended. .
  
  nelfinavir will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• nevirapine

  nevirapine will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• omaveloxolone

  omaveloxolone will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Omaveloxolone may reduce efficacy of hormonal contraceptives (eg, pill, patch, ring), implants, and progestin-only pills owing to weak CYP3A4 induction.
  
  omaveloxolone will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Omaveloxolone may reduce efficacy of hormonal contraceptives (eg, pill, patch, ring), implants, and progestin-only pills owing to weak CYP3A4 induction.

• oxcarbazepine

  oxcarbazepine will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• perampanel

  perampanel will decrease the level or effect of levonorgestrel oral by unspecified interaction mechanism. Avoid or Use Alternate Drug. Levonorgestrel levels reduced by 40% when coadministered with high dose perampanel (ie, 12 mg/day); effect on other progestins is unknown, consider back up contraception

• pentobarbital

  pentobarbital will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• pexidartinib

  levonorgestrel oral and pexidartinib both increase Other (see comment). Avoid or Use Alternate Drug. Pexidartinib can cause hepatotoxicity. Avoid coadministration of pexidartinib with other products know to cause hepatoxicity.

• phenindione

  levonorgestrel oral, phenindione. Either decreases effects of the other by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Risk of thromboembolic disorders.

• phenobarbital

  phenobarbital will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• phenytoin

  phenytoin will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• pretomanid

  levonorgestrel oral, pretomanid. Either increases toxicity of the other by Other (see comment). Avoid or Use Alternate Drug. Comment: Pretomanid regimen associated with hepatotoxicity. Avoid alcohol and hepatotoxic agents, including herbal supplements and drugs other than bedaquiline and linezolid.

• primidone

  primidone will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• protamine

  levonorgestrel oral, protamine. Either decreases effects of the other by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Risk of thromboembolic disorders.

• quinidine

  quinidine will increase the level or effect of ethinylestradiol by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug.

• ranolazine

  ethinylestradiol will increase the level or effect of ranolazine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• rifabutin

  rifabutin will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• rifampin

  rifampin will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• rifapentine

  rifapentine will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• ritonavir

  ritonavir will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  ritonavir will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  ritonavir, ethinylestradiol. Other (see comment). Avoid or Use Alternate Drug. Comment: Significant changes (increase or decrease) can occur in estrogen plasma levels. Efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended. .

• saquinavir

  saquinavir, ethinylestradiol. Other (see comment). Avoid or Use Alternate Drug. Comment: Significant changes (increase or decrease) can occur in estrogen plasma levels. Efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended. .
  
  saquinavir will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• sugammadex sodium

  sugammadex sodium decreases effects of levonorgestrel oral by receptor binding competition. Avoid or Use Alternate Drug. In vitro binding studies showed that sugammadex may bind to progestogen, thereby decreasing progestogen exposure. Therefore, a sugammadex bolus dose is considered to be equivalent to missing dose(s) of hormonal contraceptives containing an estrogen or progestogen. If an oral contraceptive is taken on the same day of sugammadex, or the patient has a transdermal or implant hormonal contraceptive, the patient must use an additional, nonhormonal contraceptive method or back-up method of contraception (eg, condoms and spermicides) for the next 7 days.

• secobarbital

  secobarbital will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• St John's Wort

  St John's Wort will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• sugammadex sodium

  sugammadex sodium decreases effects of ethinylestradiol by receptor binding competition. Avoid or Use Alternate Drug. In vitro binding studies showed that sugammadex may bind to progestogen, thereby decreasing progestogen exposure. Therefore, a sugammadex bolus dose is considered to be equivalent to missing dose(s) of hormonal contraceptives containing an estrogen or progestogen. If an oral contraceptive is taken on the same day of sugammadex, or the patient has a transdermal or implant hormonal contraceptive, the patient must use an additional, nonhormonal contraceptive method or back-up method of contraception (eg, condoms and spermicides) for the next 7 days.

• tipranavir

  tipranavir, ethinylestradiol. Other (see comment). Avoid or Use Alternate Drug. Comment: Significant changes (increase or decrease) can occur in estrogen plasma levels. Efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended. .

• topiramate

  topiramate will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• tucatinib

  tucatinib will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid concomitant use of tucatinib with CYP3A substrates, where minimal concentration changes may lead to serious or life-threatening toxicities. If unavoidable, reduce CYP3A substrate dose according to product labeling.
  
  tucatinib will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid concomitant use of tucatinib with CYP3A substrates, where minimal concentration changes may lead to serious or life-threatening toxicities. If unavoidable, reduce CYP3A substrate dose according to product labeling.

• voxelotor

  voxelotor will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Voxelotor increases systemic exposure of sensitive CYP3A4 substrates. Avoid coadministration with sensitive CYP3A4 substrates with a narrow therapeutic index. Consider dose reduction of the sensitive CYP3A4 substrate(s) if unable to avoid.
  
  voxelotor will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Voxelotor increases systemic exposure of sensitive CYP3A4 substrates. Avoid coadministration with sensitive CYP3A4 substrates with a narrow therapeutic index. Consider dose reduction of the sensitive CYP3A4 substrate(s) if unable to avoid.

Monitor Closely (186)

• albiglutide

  ethinylestradiol decreases effects of albiglutide by pharmacodynamic antagonism. Use Caution/Monitor. Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. Monitor for glycemic control in diabetic patients.
  
  levonorgestrel oral decreases effects of albiglutide by pharmacodynamic antagonism. Use Caution/Monitor. Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. Monitor for glycemic control in diabetic patients.

• alosetron

  ethinylestradiol will increase the level or effect of alosetron by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.

• amobarbital

  amobarbital will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• alprazolam

  ethinylestradiol will increase the level or effect of alprazolam by Mechanism: decreasing metabolism. Use Caution/Monitor. Ethinyl estradiol may inhibit the clearance of benzodiazepines that undergo oxidation, thereby increasing serum concentrations of concomitantly administered benzodiazepines.

• aminocaproic acid

  ethinylestradiol, aminocaproic acid. Other (see comment). Use Caution/Monitor. Comment: Concomitant use may lead to additive hypercoagulability. Estrogens increase clotting factor production and platelet aggregation; aminocaproic acid inhibits fibrinolysis and activity of plasminogen.

• amoxicillin

  amoxicillin will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor. Antibiotics may decrease hormonal contraceptive efficacy.

• ampicillin

  ampicillin will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• artemether/lumefantrine

  artemether/lumefantrine will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• atazanavir

  atazanavir, levonorgestrel oral. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Atazanavir may increase or decrease levels of levonorgestrel oral. Use alternatives if available. .

• atogepant

  ethinylestradiol will increase the level or effect of atogepant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• atorvastatin

  atorvastatin will increase the level or effect of ethinylestradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

• axitinib

  ethinylestradiol increases levels of axitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• bendamustine

  ethinylestradiol increases levels of bendamustine by decreasing metabolism. Use Caution/Monitor. Bendamustine is metabolized to minimally active metabolites by CYP1A2. Ethinyl estradiol is a weak CYP1A2 inhibitor and concurrent administration may increase bendamustine concentrations in plasma. .

• bosentan

  bosentan decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• caffeine

  ethinylestradiol will increase the level or effect of caffeine by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.

• carbamazepine

  carbamazepine decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• cefaclor

  cefaclor will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• cefadroxil

  cefadroxil will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• cefazolin

  cefazolin will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• cefdinir

  cefdinir will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• cefepime

  cefepime will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• cefixime

  cefixime will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• cefotaxime

  cefotaxime will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• cefprozil

  cefprozil will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• ceftazidime

  ceftazidime will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• ceftibuten

  ceftibuten will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• cefuroxime

  cefuroxime will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• cenobamate

  cenobamate will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Increase dose of CYP3A4 substrate, as needed, when coadministered with cenobamate.
  
  cenobamate will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Increase dose of CYP3A4 substrate, as needed, when coadministered with cenobamate.
  
  cenobamate will decrease the level or effect of ethinylestradiol by unspecified interaction mechanism. Modify Therapy/Monitor Closely. Advise women to use additional or alternative non-hormonal birth control when concomitantly using cenobamate with oral contraceptives.
  
  cenobamate will decrease the level or effect of levonorgestrel oral by unspecified interaction mechanism. Modify Therapy/Monitor Closely. Advise women to use additional or alternative non-hormonal birth control when concomitantly using cenobamate with oral contraceptives.

• cephalexin

  cephalexin will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• ceritinib

  ceritinib will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• ceritinib

  ceritinib will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• chloramphenicol

  chloramphenicol will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• cimetidine

  cimetidine will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• ciprofloxacin

  ciprofloxacin will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• clarithromycin

  clarithromycin will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Modify Therapy/Monitor Closely.

• clindamycin

  clindamycin will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• clobazam

  clobazam will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Clobazam is a weak CYP3A4 inducer; effectiveness of hormonal contraceptives may be diminished when given concurrently with clobazam. Additional non-hormonal forms of contraception are recommended.
  
  clobazam will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Clobazam is a weak CYP3A4 inducer; effectiveness of hormonal contraceptives may be diminished when given concurrently with clobazam. Additional non-hormonal forms of contraception are recommended.

• clonazepam

  ethinylestradiol will increase the level or effect of clonazepam by Mechanism: decreasing metabolism. Use Caution/Monitor. Ethinyl estradiol may inhibit the clearance of benzodiazepines that undergo oxidation, thereby increasing serum concentrations of concomitantly administered benzodiazepines.

• crofelemer

  crofelemer increases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Crofelemer has the potential to inhibit CYP3A4 at concentrations expected in the gut; unlikely to inhibit systemically because minimally absorbed.

• cyclosporine

  ethinylestradiol increases levels of cyclosporine by unknown mechanism. Use Caution/Monitor.
  
  levonorgestrel oral, cyclosporine. Either increases levels of the other by decreasing metabolism. Use Caution/Monitor. Combined oral contraceptives containing EE may inhibit the metabolism and increase plasma concentrations of cyclosporine.

• dabrafenib

  dabrafenib will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.
  
  dabrafenib will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.

• darunavir

  darunavir will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Significant changes (increase or decrease) can occur in estrogen plasma levels. Efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• dexamethasone

  dexamethasone decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• dasatinib

  ethinylestradiol will increase the level or effect of dasatinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• deferasirox

  deferasirox will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• demeclocycline

  demeclocycline will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• diazepam

  ethinylestradiol will increase the level or effect of diazepam by Mechanism: decreasing metabolism. Use Caution/Monitor. Ethinyl estradiol may inhibit the clearance of benzodiazepines that undergo oxidation, thereby increasing serum concentrations of concomitantly administered benzodiazepines.

• dicloxacillin

  dicloxacillin will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• doxycycline

  doxycycline will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• efavirenz

  efavirenz decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• elagolix

  elagolix decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Elagolix is a weak-to-moderate CYP3A4 inducer. Monitor CYP3A substrates if coadministered. Consider increasing CYP3A substrate dose if needed.
  
  elagolix will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Elagolix is a weak-to-moderate CYP3A4 inducer. Monitor CYP3A substrates if coadministered. Consider increasing CYP3A substrate dose if needed.

• eltrombopag

  ethinylestradiol will increase the level or effect of eltrombopag by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.

• encorafenib

  encorafenib, levonorgestrel oral. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Encorafenib both inhibits and induces CYP3A4 at clinically relevant plasma concentrations. Coadministration of encorafenib with sensitive CYP3A4 substrates may result in increased toxicity or decreased efficacy of these agents.

• elvitegravir/cobicistat/emtricitabine/tenofovir DF

  elvitegravir/cobicistat/emtricitabine/tenofovir DF increases levels of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Cobicistat is a CYP3A4 inhibitor; contraindicated with CYP3A4 substrates for which elevated plasma concentrations are associated with serious and/or life-threatening events.

• encorafenib

  encorafenib will increase the level or effect of ethinylestradiol by Other (see comment). Modify Therapy/Monitor Closely. Encorafenib (a BCRP inhibitor) may increase the concentration and toxicities of BCRP substrates. Closely monitor for signs and symptoms of increased exposure and consider adjusting the dose of these substrates.

• enzalutamide

  enzalutamide decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• erythromycin base

  erythromycin base will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor. Antibiotics may decrease hormonal contraceptive efficacy.

• erythromycin ethylsuccinate

  erythromycin ethylsuccinate will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor. Antibiotics may decrease hormonal contraceptive efficacy.

• erythromycin lactobionate

  erythromycin lactobionate will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor. Antibiotics may decrease hormonal contraceptive efficacy.

• erythromycin stearate

  erythromycin stearate will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor. Antibiotics may decrease hormonal contraceptive efficacy.

• etravirine

  etravirine will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.
  
  etravirine decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• exenatide injectable solution

  levonorgestrel oral, exenatide injectable solution. Other (see comment). Use Caution/Monitor. Comment: Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. The effect of exenatide to slow gastric emptying may reduce the extent and rate of oral medications that require rapid GI absorption. Advise patients to take oral contraceptives at least 1 hr before exenatide. .
  
  ethinylestradiol, exenatide injectable solution. Other (see comment). Use Caution/Monitor. Comment: Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. The effect of exenatide to slow gastric emptying may reduce the extent and rate of oral medications that require rapid GI absorption. Advise patients to take oral contraceptives at least 1 hr before exenatide. .

• exenatide injectable suspension

  ethinylestradiol, exenatide injectable suspension. Other (see comment). Use Caution/Monitor. Comment: Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. The effect of exenatide to slow gastric emptying may reduce the extent and rate of oral medications that require rapid GI absorption. Advise patients to take oral contraceptives at least 1 hr before exenatide.
  
  levonorgestrel oral, exenatide injectable suspension. Other (see comment). Use Caution/Monitor. Comment: Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. The effect of exenatide to slow gastric emptying may reduce the extent and rate of oral medications that require rapid GI absorption. Advise patients to take oral contraceptives at least 1 hr before exenatide.

• fedratinib

  fedratinib will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP3A4 substrates as necessary.
  
  fedratinib will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP3A4 substrates as necessary.

• felbamate

  felbamate decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• finerenone

  ethinylestradiol will increase the level or effect of finerenone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Monitor serum potassium during initiation and dosage adjustment of either finererone or weak CYP3A4 inhibitors. Adjust finererone dosage as needed.

• flibanserin

  ethinylestradiol will increase the level or effect of flibanserin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Increased flibanserin adverse effects may occur if coadministered with multiple weak CYP3A4 inhibitors.

• fluconazole

  fluconazole will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• fluvoxamine

  ethinylestradiol will increase the level or effect of fluvoxamine by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.

• fosphenytoin

  fosphenytoin decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• fostemsavir

  fostemsavir will increase the level or effect of ethinylestradiol by Other (see comment). Modify Therapy/Monitor Closely. Fostemsavir inhibits BCRP transporters. If possible, avoid coadministration or modify dose of BCRP substrate coadministered with fostemsavir. Do not ethinyl estradiol dose of exceed 30 mcg/day.

• gemifloxacin

  gemifloxacin will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• grapefruit

  grapefruit will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• green tea

  ethinylestradiol increases levels of green tea by decreasing elimination. Use Caution/Monitor.

• griseofulvin

  griseofulvin decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• hemin

  ethinylestradiol decreases effects of hemin by pharmacodynamic antagonism. Use Caution/Monitor. Drugs that increase delta-aminolevulinic acid synthetase may decrease hemin effect.

• hyaluronidase

  ethinylestradiol decreases effects of hyaluronidase by Other (see comment). Use Caution/Monitor. Comment: Estrogens, when given in large systemic doses, may render tissues partially resistant to the action of hyaluronidase. Patients may require larger amounts of hyaluronidase for equivalent dispersing effect.

• iloperidone

  iloperidone increases levels of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Iloperidone is a time-dependent CYP3A inhibitor and may lead to increased plasma levels of drugs predominantly eliminated by CYP3A4.
  
  iloperidone increases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Iloperidone is a time-dependent CYP3A inhibitor and may lead to increased plasma levels of drugs predominantly eliminated by CYP3A4.

• insulin aspart

  ethinylestradiol decreases effects of insulin aspart by pharmacodynamic antagonism. Use Caution/Monitor. Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. Monitor for glycemic control in diabetic patients.

• insulin degludec

  levonorgestrel oral decreases effects of insulin degludec by pharmacodynamic antagonism. Use Caution/Monitor. Progestins may impair glucose tolerance.

• insulin degludec

  ethinylestradiol decreases effects of insulin degludec by pharmacodynamic antagonism. Use Caution/Monitor. Estrogens may impair glucose tolerance.

• insulin degludec/insulin aspart

  ethinylestradiol decreases effects of insulin degludec/insulin aspart by pharmacodynamic antagonism. Use Caution/Monitor. Estrogens may impair glucose tolerance.
  
  levonorgestrel oral decreases effects of insulin degludec/insulin aspart by pharmacodynamic antagonism. Use Caution/Monitor. Progestins may impair glucose tolerance.

• insulin detemir

  ethinylestradiol decreases effects of insulin detemir by pharmacodynamic antagonism. Use Caution/Monitor. Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. Monitor for glycemic control in diabetic patients.

• insulin inhaled

  levonorgestrel oral decreases effects of insulin inhaled by pharmacodynamic antagonism. Use Caution/Monitor. Progestins may impair glucose tolerance.

• insulin glargine

  ethinylestradiol decreases effects of insulin glargine by pharmacodynamic antagonism. Use Caution/Monitor. Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. Monitor for glycemic control in diabetic patients.

• insulin glulisine

  ethinylestradiol decreases effects of insulin glulisine by pharmacodynamic antagonism. Use Caution/Monitor. Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. Monitor for glycemic control in diabetic patients.

• insulin inhaled

  ethinylestradiol decreases effects of insulin inhaled by pharmacodynamic antagonism. Use Caution/Monitor. Estrogens may impair glucose tolerance.

• insulin lispro

  ethinylestradiol decreases effects of insulin lispro by pharmacodynamic antagonism. Use Caution/Monitor. Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. Monitor for glycemic control in diabetic patients.

• insulin NPH

  ethinylestradiol decreases effects of insulin NPH by pharmacodynamic antagonism. Use Caution/Monitor. Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. Monitor for glycemic control in diabetic patients.

• insulin regular human

  ethinylestradiol decreases effects of insulin regular human by pharmacodynamic antagonism. Use Caution/Monitor. Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. Monitor for glycemic control in diabetic patients.

• isavuconazonium sulfate

  ethinylestradiol will increase the level or effect of isavuconazonium sulfate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• istradefylline

  istradefylline will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Istradefylline 40 mg/day increased peak levels and AUC of CYP3A4 substrates in clinical trials. This effect was not observed with istradefylline 20 mg/day. Consider dose reduction of sensitive CYP3A4 substrates.
  
  istradefylline will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Istradefylline 40 mg/day increased peak levels and AUC of CYP3A4 substrates in clinical trials. This effect was not observed with istradefylline 20 mg/day. Consider dose reduction of sensitive CYP3A4 substrates.

• itraconazole

  itraconazole will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inhibitors such as itraconazole may increase plasma hormone levels.

• ivosidenib

  ivosidenib will decrease the level or effect of levonorgestrel oral by unspecified interaction mechanism. Modify Therapy/Monitor Closely. Coadministration of ivosidenib may decrease the concentrations of hormonal contraceptives, consider alternative methods of contraception in patients receiving ivosidenib.

• ketoconazole

  ketoconazole will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inhibitors such as ketoconazole may increase plasma hormone levels.

• lamotrigine

  levonorgestrel oral will decrease the level or effect of lamotrigine by increasing hepatic clearance. Use Caution/Monitor. Combination oral contraceptives have been shown to significantly decrease plasma concentrations of lamotrigine, likely due to induction of lamotrigine glucuronidation.
  
  ethinylestradiol decreases levels of lamotrigine by increasing hepatic clearance. Use Caution/Monitor. Combination oral contraceptives have been shown to significantly decrease plasma concentrations of lamotrigine, likely due to induction of lamotrigine glucuronidation.

• lapatinib

  ethinylestradiol will increase the level or effect of lapatinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• lenacapavir

  lenacapavir will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Lencapavir may increase CYP3A4 substrates initiated within 9 months after last SC dose of lenacapavir, which may increase potential risk of adverse reactions of CYP3A4 substrates.

• lemborexant

  ethinylestradiol will increase the level or effect of lemborexant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Lower nightly dose of lemborexant recommended if coadministered with weak CYP3A4 inhibitors. See drug monograph for specific dosage modification.

• lenacapavir

  lenacapavir will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Lencapavir (a moderate CYP3A4 inhibitor) may increase CYP3A4 substrates initiated within 9 months after last SC dose of lenacapavir, which may increase potential risk of adverse reactions of CYP3A4 substrates.

• levofloxacin

  levofloxacin will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• levoketoconazole

  levoketoconazole will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inhibitors such as ketoconazole may increase plasma hormone levels.

• liraglutide

  ethinylestradiol decreases effects of liraglutide by pharmacodynamic antagonism. Use Caution/Monitor. Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. Monitor for glycemic control in diabetic patients.
  
  levonorgestrel oral decreases effects of liraglutide by pharmacodynamic antagonism. Use Caution/Monitor. Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. Monitor for glycemic control in diabetic patients.

• lixisenatide (DSC)

  lixisenatide (DSC) will decrease the level or effect of ethinylestradiol by inhibition of GI absorption. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. GLP1 agonists delay gastric emptying, which may affect absorption of concomitantly administered oral medications. Oral contraceptives should be taken at least 1 hr before lixisenatide administration or 11 hr after lixisenatide.

• maraviroc

  levonorgestrel oral increases levels of maraviroc by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potential for increased toxicity.

• lomitapide

  ethinylestradiol increases levels of lomitapide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Lomitapide dose should not exceed 30 mg/day.

• lonapegsomatropin

  ethinylestradiol will decrease the level or effect of lonapegsomatropin by Other (see comment). Use Caution/Monitor. Oral estrogens may reduce serum insulin-like growth factor-1 response to lonapegsomatropin. Patients receiving oral estrogen replacement may require higher lonapegsomatropin dosages.
  
  ethinylestradiol will decrease the level or effect of lonapegsomatropin by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Oral estrogens may reduce serum insulin-like growth factor I (IGF-1) response to growth hormone (GH) analogs. Higher GH dose may be required

• lorlatinib

  lorlatinib will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• lumefantrine

  lumefantrine will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• metformin

  ethinylestradiol decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.
  
  levonorgestrel oral decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

• metronidazole

  metronidazole will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• mifepristone

  mifepristone decreases effects of levonorgestrel oral by pharmacodynamic antagonism. Use Caution/Monitor. Backup contraceptive method recommended.

• mexiletine

  ethinylestradiol will increase the level or effect of mexiletine by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.

• midazolam

  ethinylestradiol will increase the level or effect of midazolam by Mechanism: decreasing metabolism. Use Caution/Monitor. Ethinyl estradiol may inhibit the clearance of benzodiazepines that undergo oxidation, thereby increasing serum concentrations of concomitantly administered benzodiazepines.

• midazolam intranasal

  ethinylestradiol will increase the level or effect of midazolam intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of mild CYP3A4 inhibitors with midazolam intranasal may cause higher midazolam systemic exposure, which may prolong sedation.

• mifepristone

  mifepristone decreases effects of ethinylestradiol by pharmacodynamic antagonism. Use Caution/Monitor. Backup contraceptive method recommended.

• minocycline

  minocycline will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• mitotane

  mitotane decreases levels of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Mitotane is a strong inducer of cytochrome P-4503A4; monitor when coadministered with CYP3A4 substrates for possible dosage adjustments.
  
  mitotane decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Mitotane is a strong inducer of cytochrome P-4503A4; monitor when coadministered with CYP3A4 substrates for possible dosage adjustments.

• momelotinib

  momelotinib increases toxicity of ethinylestradiol by plasma protein binding competition. Modify Therapy/Monitor Closely. Momelotinib (BCRP inhibitor) may increase exposure of BCRP substrates, which may increase the risk of BCRP substrate adverse reactions. Dose adjustment of other BCRP substrates may necessary.

• mycophenolate

  mycophenolate decreases levels of levonorgestrel oral by unspecified interaction mechanism. Use Caution/Monitor. Consider additional birth control methods during mycophenolate administration.

• moxifloxacin

  moxifloxacin will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• nafcillin

  nafcillin will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
  
  nafcillin decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• neomycin PO

  neomycin PO will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• nevirapine

  nevirapine decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• nicardipine

  ethinylestradiol will increase the level or effect of nicardipine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• nilotinib

  ethinylestradiol will increase the level or effect of nilotinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• nirmatrelvir

  nirmatrelvir will decrease the level or effect of ethinylestradiol by increasing metabolism. Modify Therapy/Monitor Closely. Consider using additional nonhormonal contraceptive method for remainder of cycle. Mechanism unknown, but possibly by ritonavir CYP2C9 or CYP1A2 induction.

• nirmatrelvir/ritonavir

  nirmatrelvir/ritonavir will decrease the level or effect of ethinylestradiol by increasing metabolism. Modify Therapy/Monitor Closely. Consider using additional nonhormonal contraceptive method for remainder of cycle. Mechanism unknown, but possibly by ritonavir CYP2C9 or CYP1A2 induction.

• nitrofurantoin

  nitrofurantoin will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• ofloxacin

  ofloxacin will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• olanzapine

  ethinylestradiol will increase the level or effect of olanzapine by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.

• oteseconazole

  oteseconazole will increase the level or effect of ethinylestradiol by Other (see comment). Modify Therapy/Monitor Closely. Otesezonale, a BCRP inhibitor, may increase the effects and risk of toxicities of BCRP substrates. Use lowest starting dose of BCRP substrate, or consider reducing BCRP substrate dose.

• oxcarbazepine

  oxcarbazepine decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• paromomycin

  paromomycin will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• penicillin G aqueous

  penicillin G aqueous decreases levels of ethinylestradiol by increasing metabolism. Use Caution/Monitor. Risk of oral contraceptive failure.

• penicillin VK

  penicillin VK will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• pentobarbital

  pentobarbital decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• phenobarbital

  phenobarbital decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• phenytoin

  phenytoin decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• pioglitazone

  pioglitazone decreases levels of ethinylestradiol by unknown mechanism. Use Caution/Monitor.

• pitolisant

  pitolisant will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Pitolisant is a borderline/weak inducer of CYP3A4. Monitor sensitive CYP3A4 substrates for reduced effectiveness if coadministered.

• posaconazole

  posaconazole will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• primidone

  primidone decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• quinupristin/dalfopristin

  quinupristin/dalfopristin will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• ramelteon

  ethinylestradiol will increase the level or effect of ramelteon by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.

• rasagiline

  ethinylestradiol will increase the level or effect of rasagiline by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor. Recommended dose of rasagiline is 0.5mg daily in combination with CYP1A2 inhibitors.

• ribociclib

  ribociclib will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
  
  ribociclib will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• rifabutin

  rifabutin decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• romidepsin

  romidepsin decreases effects of ethinylestradiol by receptor binding competition. Use Caution/Monitor.

• rifampin

  rifampin decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• rifapentine

  rifapentine decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• ropinirole

  ethinylestradiol will increase the level or effect of ropinirole by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.
  
  ethinylestradiol increases levels of ropinirole by unspecified interaction mechanism. Use Caution/Monitor.

• rucaparib

  rucaparib will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust dosage of CYP3A4 substrates, if clinically indicated.
  
  rucaparib will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust dosage of CYP3A4 substrates, if clinically indicated.

• rufinamide

  rufinamide decreases effects of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Rufinamide is a weak inducer of the CYP 3A4 enzyme and can decrease exposure of drugs that are substrates of CYP3A4. .

• secobarbital

  secobarbital will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• selegiline

  ethinylestradiol increases levels of selegiline by Other (see comment). Use Caution/Monitor. Comment: Oral contraceptives inhibit the N demethylatin of selegiline.

• selegiline transdermal

  ethinylestradiol increases levels of selegiline transdermal by Other (see comment). Use Caution/Monitor. Comment: Oral contraceptives inhibit the N demethylatin of selegiline.

• siltuximab

  siltuximab, ethinylestradiol. Other (see comment). Use Caution/Monitor. Comment: CYP450 activity in the liver is down regulated by infection and inflammation stimuli including cytokines (eg, IL-6); inhibition of IL-6 by siltuximab may restore CYP450 enzymatic activity; caution if coadministered with CYP substrates that have a narrow therapeutic index.
  
  siltuximab, levonorgestrel oral. Other (see comment). Use Caution/Monitor. Comment: CYP450 activity in the liver is down regulated by infection and inflammation stimuli including cytokines (eg, IL-6); inhibition of IL-6 by siltuximab may restore CYP450 enzymatic activity; caution if coadministered with CYP substrates that have a narrow therapeutic index.

• St John's Wort

  St John's Wort decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• somapacitan

  ethinylestradiol will decrease the level or effect of somapacitan by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Oral estrogens may reduce serum insulin-like growth factor I (IGF-1) response to growth hormone (GH) analogs. Higher GH dose may be required

• somatrogon

  ethinylestradiol will decrease the level or effect of somatrogon by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Oral estrogens may reduce serum insulin-like growth factor I (IGF-1) response to growth hormone (GH) analogs. Higher GH dose may be required

• somatropin

  ethinylestradiol will decrease the level or effect of somatropin by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Oral estrogens may reduce serum insulin-like growth factor I (IGF-1) response to growth hormone (GH) analogs. Higher GH dose may be required

• stiripentol

  stiripentol, levonorgestrel oral. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Stiripentol is a CYP3A4 inhibitor and inducer. Monitor CYP3A4 substrates coadministered with stiripentol for increased or decreased effects. CYP3A4 substrates may require dosage adjustment.
  
  stiripentol, ethinylestradiol. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Stiripentol is a CYP3A4 inhibitor and inducer. Monitor CYP3A4 substrates coadministered with stiripentol for increased or decreased effects. CYP3A4 substrates may require dosage adjustment.

• sulfadiazine

  sulfadiazine will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• tazemetostat

  tazemetostat will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• sulfamethoxazole

  sulfamethoxazole will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• sulfisoxazole

  sulfisoxazole will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• tacrolimus

  ethinylestradiol will increase the level or effect of tacrolimus by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• tazemetostat

  tazemetostat will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
  
  ethinylestradiol will increase the level or effect of tazemetostat by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• tecovirimat

  tecovirimat will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Tecovirimat is a weak CYP3A4 inducer. Monitor sensitive CYP3A4 substrates for effectiveness if coadministered.
  
  tecovirimat will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Tecovirimat is a weak CYP3A4 inducer. Monitor sensitive CYP3A4 substrates for effectiveness if coadministered.

• teriflunomide

  teriflunomide increases levels of levonorgestrel oral by unknown mechanism. Use Caution/Monitor.
  
  teriflunomide increases levels of ethinylestradiol by unknown mechanism. Use Caution/Monitor.

• tesamorelin

  tesamorelin will decrease the level or effect of levonorgestrel oral by altering metabolism. Use Caution/Monitor. Use alternative contraception

• tetracycline

  tetracycline will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• theophylline

  ethinylestradiol will increase the level or effect of theophylline by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.

• ticarcillin

  ticarcillin will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• tigecycline

  tigecycline will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• tinidazole

  ethinylestradiol will increase the level or effect of tinidazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• tizanidine

  ethinylestradiol will increase the level or effect of tizanidine by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor. Monitor for tizanidine adverse effects (eg, hypotension or bradycardia)

• tolterodine

  ethinylestradiol will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• topiramate

  topiramate decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• triazolam

  ethinylestradiol will increase the level or effect of triazolam by Mechanism: decreasing metabolism. Use Caution/Monitor. Ethinyl estradiol may inhibit the clearance of benzodiazepines that undergo oxidation, thereby increasing serum concentrations of concomitantly administered benzodiazepines.

• trimethoprim

  trimethoprim will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• ursodiol

  ethinylestradiol decreases effects of ursodiol by pharmacodynamic antagonism. Use Caution/Monitor.

• valoctocogene roxaparvovec

  levonorgestrel oral and valoctocogene roxaparvovec both increase Other (see comment). Use Caution/Monitor. Medications that may cause hepatotoxicity when combined with valoctogene roxaparvovec may potentiate the risk of elevated liver enzymes. Closely monitor these medications and consider alternative medications in case of potential drug interactions.
  
  ethinylestradiol and valoctocogene roxaparvovec both increase Other (see comment). Use Caution/Monitor. Medications that may cause hepatotoxicity when combined with valoctogene roxaparvovec may potentiate the risk of elevated liver enzymes. Closely monitor these medications and consider alternative medications in case of potential drug interactions.

• valproic acid

  ethinylestradiol will decrease the level or effect of valproic acid by increasing elimination. Modify Therapy/Monitor Closely. May lead to increased seizure frequency

• voriconazole

  voriconazole will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

Minor (24)

• acetazolamide

  acetazolamide will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
  
  acetazolamide will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• amitriptyline

  ethinylestradiol, amitriptyline. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Estrogens and progestins may decr tricyclic antidepressant effects, while increasing TCA plasma concentration and adverse effects.

• anastrozole

  anastrozole will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• amoxapine

  ethinylestradiol, amoxapine. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Estrogens and progestins may decr tricyclic antidepressant effects, while increasing TCA plasma concentration and adverse effects.

• anastrozole

  anastrozole will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• antipyrine

  ethinylestradiol will increase the level or effect of antipyrine by affecting hepatic enzyme CYP1A2 metabolism. Minor/Significance Unknown.

• asenapine

  ethinylestradiol will increase the level or effect of asenapine by affecting hepatic enzyme CYP1A2 metabolism. Minor/Significance Unknown.

• clarithromycin

  ethinylestradiol will increase the level or effect of clarithromycin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• clomipramine

  ethinylestradiol will increase the level or effect of clomipramine by affecting hepatic enzyme CYP1A2 metabolism. Minor/Significance Unknown.

• cyclophosphamide

  cyclophosphamide will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
  
  cyclophosphamide will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• desipramine

  ethinylestradiol, desipramine. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Oxidative metabolism of TCAs may be decreased by ethinyl estradiol. Increased antidepressant serum concentrations may occur. Potential for increased TCA adverse effects.

• enasidenib

  enasidenib, levonorgestrel oral. unknown mechanism. Minor/Significance Unknown. Coadministration of enasidenib may increase or decrease the concentrations of combined hormonal contraceptives. Clinical significance of this interaction is unknown.

• dosulepin

  ethinylestradiol, dosulepin. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Oxidative metabolism of TCAs may be decreased by ethinyl estradiol. Increased antidepressant serum concentrations may occur. Potential for increased TCA adverse effects.

• doxepin

  ethinylestradiol, doxepin. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Oxidative metabolism of TCAs may be decreased by ethinyl estradiol. Increased antidepressant serum concentrations may occur. Potential for increased TCA adverse effects.

• duloxetine

  ethinylestradiol will increase the level or effect of duloxetine by affecting hepatic enzyme CYP1A2 metabolism. Minor/Significance Unknown.

• enasidenib

  enasidenib, ethinylestradiol. unknown mechanism. Minor/Significance Unknown. Coadministration of enasidenib may increase or decrease the concentrations of combined hormonal contraceptives. Clinical significance of this interaction is unknown.

• eplerenone

  ethinylestradiol will increase the level or effect of eplerenone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• felbamate

  felbamate decreases levels of ethinylestradiol by unknown mechanism. Minor/Significance Unknown.

• frovatriptan

  ethinylestradiol will increase the level or effect of frovatriptan by affecting hepatic enzyme CYP1A2 metabolism. Minor/Significance Unknown.

• imipramine

  ethinylestradiol, imipramine. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Oxidative metabolism of TCAs may be decreased by ethinyl estradiol. Increased antidepressant serum concentrations may occur. Potential for increased TCA adverse effects.

• larotrectinib

  larotrectinib will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
  
  larotrectinib will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• levoketoconazole

  levoketoconazole will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• mineral oil

  mineral oil decreases levels of ethinylestradiol by inhibition of GI absorption. Applies only to oral form of both agents. Minor/Significance Unknown.

• naratriptan

  ethinylestradiol increases effects of naratriptan by unspecified interaction mechanism. Minor/Significance Unknown. The clinical implication of these interactions is unknown.

• acetazolamide

  Minor (2)acetazolamide will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
  
  acetazolamide will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• albiglutide

  Monitor Closely (2)ethinylestradiol decreases effects of albiglutide by pharmacodynamic antagonism. Use Caution/Monitor. Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. Monitor for glycemic control in diabetic patients.
  
  levonorgestrel oral decreases effects of albiglutide by pharmacodynamic antagonism. Use Caution/Monitor. Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. Monitor for glycemic control in diabetic patients.

• alosetron

  Monitor Closely (1)ethinylestradiol will increase the level or effect of alosetron by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.

• alprazolam

  Monitor Closely (1)ethinylestradiol will increase the level or effect of alprazolam by Mechanism: decreasing metabolism. Use Caution/Monitor. Ethinyl estradiol may inhibit the clearance of benzodiazepines that undergo oxidation, thereby increasing serum concentrations of concomitantly administered benzodiazepines.

• aminocaproic acid

  Monitor Closely (1)ethinylestradiol, aminocaproic acid. Other (see comment). Use Caution/Monitor. Comment: Concomitant use may lead to additive hypercoagulability. Estrogens increase clotting factor production and platelet aggregation; aminocaproic acid inhibits fibrinolysis and activity of plasminogen.

• amitriptyline

  Minor (1)ethinylestradiol, amitriptyline. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Estrogens and progestins may decr tricyclic antidepressant effects, while increasing TCA plasma concentration and adverse effects.

• amobarbital

  Monitor Closely (1)amobarbital will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)amobarbital will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• amoxapine

  Minor (1)ethinylestradiol, amoxapine. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Estrogens and progestins may decr tricyclic antidepressant effects, while increasing TCA plasma concentration and adverse effects.

• amoxicillin

  Monitor Closely (1)amoxicillin will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor. Antibiotics may decrease hormonal contraceptive efficacy.

• ampicillin

  Monitor Closely (1)ampicillin will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• anastrozole

  Minor (2)anastrozole will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
  
  anastrozole will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.Serious - Use Alternative (1)ethinylestradiol decreases effects of anastrozole by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Anastrozole should not be given concurrently with any estrogens or estrogen-containing products.

• antipyrine

  Minor (1)ethinylestradiol will increase the level or effect of antipyrine by affecting hepatic enzyme CYP1A2 metabolism. Minor/Significance Unknown.

• antithrombin alfa

  Serious - Use Alternative (1)levonorgestrel oral, antithrombin alfa. Either decreases effects of the other by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Risk of thromboembolic disorders.

• antithrombin III

  Serious - Use Alternative (1)levonorgestrel oral, antithrombin III. Either decreases effects of the other by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Risk of thromboembolic disorders.

• apalutamide

  Serious - Use Alternative (2)apalutamide will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of apalutamide, a strong CYP3A4 inducer, with drugs that are CYP3A4 substrates can result in lower exposure to these medications. Avoid or substitute another drug for these medications when possible. Evaluate for loss of therapeutic effect if medication must be coadministered. Adjust dose according to prescribing information if needed.
  
  apalutamide will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of apalutamide, a strong CYP3A4 inducer, with drugs that are CYP3A4 substrates can result in lower exposure to these medications. Avoid or substitute another drug for these medications when possible. Evaluate for loss of therapeutic effect if medication must be coadministered. Adjust dose according to prescribing information if needed.

• argatroban

  Serious - Use Alternative (1)levonorgestrel oral, argatroban. Either decreases effects of the other by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Risk of thromboembolic disorders.

• armodafinil

  Serious - Use Alternative (1)armodafinil will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• artemether/lumefantrine

  Monitor Closely (1)artemether/lumefantrine will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• asenapine

  Minor (1)ethinylestradiol will increase the level or effect of asenapine by affecting hepatic enzyme CYP1A2 metabolism. Minor/Significance Unknown.

• atazanavir

  Monitor Closely (1)atazanavir, levonorgestrel oral. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Atazanavir may increase or decrease levels of levonorgestrel oral. Use alternatives if available. .Serious - Use Alternative (1)atazanavir, ethinylestradiol. Other (see comment). Avoid or Use Alternate Drug. Comment: Significant changes (increase or decrease) can occur in estrogen plasma levels. Efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended. .

• atogepant

  Monitor Closely (1)ethinylestradiol will increase the level or effect of atogepant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• atorvastatin

  Monitor Closely (1)atorvastatin will increase the level or effect of ethinylestradiol by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.

• axitinib

  Monitor Closely (1)ethinylestradiol increases levels of axitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• belzutifan

  Serious - Use Alternative (2)belzutifan will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of belzutifan with hormonal contraceptives may lead to contraceptive failure or increased breakthrough bleeding. Advise females of reproductive potential to use effective nonhormonal contraception. Based on animal studies, belzutifan can cause fetal harm.
  
  belzutifan will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of belzutifan with hormonal contraceptives may lead to contraceptive failure or increased breakthrough bleeding. Advise females of reproductive potential to use effective nonhormonal contraception. Based on animal studies, belzutifan can cause fetal harm.

• bemiparin

  Serious - Use Alternative (1)levonorgestrel oral, bemiparin. Either decreases effects of the other by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Risk of thromboembolic disorders.

• bendamustine

  Monitor Closely (1)ethinylestradiol increases levels of bendamustine by decreasing metabolism. Use Caution/Monitor. Bendamustine is metabolized to minimally active metabolites by CYP1A2. Ethinyl estradiol is a weak CYP1A2 inhibitor and concurrent administration may increase bendamustine concentrations in plasma. .

• bivalirudin

  Serious - Use Alternative (1)levonorgestrel oral, bivalirudin. Either decreases effects of the other by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Risk of thromboembolic disorders.

• bosentan

  Monitor Closely (1)bosentan decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)bosentan will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• brigatinib

  Serious - Use Alternative (2)brigatinib will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Brigatinib induces CYP3A4 in vitro. Coadministration of hormonal contraceptives with brigatinib can result in decreased concentrations and loss of efficacy. Brigatinib can cause fetal harm. Women should use an effective nonhormonal method of contraception during treatment and for at least 4 months after the last brigatinib dose.
  
  brigatinib will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Brigatinib induces CYP3A4 in vitro. Coadministration of hormonal contraceptives with brigatinib can result in decreased concentrations and loss of efficacy. Brigatinib can cause fetal harm. Women should use an effective nonhormonal method of contraception during treatment and for at least 4 months after the last brigatinib dose.

• butabarbital

  Serious - Use Alternative (1)butabarbital will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• caffeine

  Monitor Closely (1)ethinylestradiol will increase the level or effect of caffeine by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.

• calaspargase pegol

  Serious - Use Alternative (2)calaspargase pegol, levonorgestrel oral. unknown mechanism. Avoid or Use Alternate Drug. Due to the potential for an indirect interaction between calaspargase pegol and oral contraceptives, concomitant use of these drugs is not recommended. Use another non-oral contraceptive method for females of childbearing potential.
  
  calaspargase pegol, ethinylestradiol. unknown mechanism. Avoid or Use Alternate Drug. Due to the potential for an indirect interaction between calaspargase pegol and oral contraceptives, concomitant use of these drugs is not recommended. Use another non-oral contraceptive method for females of childbearing potential.

• carbamazepine

  Monitor Closely (1)carbamazepine decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (2)ethinylestradiol will increase the level or effect of carbamazepine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.
  
  carbamazepine will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• cefaclor

  Monitor Closely (1)cefaclor will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• cefadroxil

  Monitor Closely (1)cefadroxil will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• cefazolin

  Monitor Closely (1)cefazolin will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• cefdinir

  Monitor Closely (1)cefdinir will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• cefepime

  Monitor Closely (1)cefepime will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• cefixime

  Monitor Closely (1)cefixime will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• cefotaxime

  Monitor Closely (1)cefotaxime will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• cefprozil

  Monitor Closely (1)cefprozil will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• ceftazidime

  Monitor Closely (1)ceftazidime will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• ceftibuten

  Monitor Closely (1)ceftibuten will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• cefuroxime

  Monitor Closely (1)cefuroxime will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• cenobamate

  Monitor Closely (4)cenobamate will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Increase dose of CYP3A4 substrate, as needed, when coadministered with cenobamate.
  
  cenobamate will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Increase dose of CYP3A4 substrate, as needed, when coadministered with cenobamate.
  
  cenobamate will decrease the level or effect of ethinylestradiol by unspecified interaction mechanism. Modify Therapy/Monitor Closely. Advise women to use additional or alternative non-hormonal birth control when concomitantly using cenobamate with oral contraceptives.
  
  cenobamate will decrease the level or effect of levonorgestrel oral by unspecified interaction mechanism. Modify Therapy/Monitor Closely. Advise women to use additional or alternative non-hormonal birth control when concomitantly using cenobamate with oral contraceptives.

• cephalexin

  Monitor Closely (1)cephalexin will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• ceritinib

  Monitor Closely (2)ceritinib will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
  
  ceritinib will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• chloramphenicol

  Monitor Closely (1)chloramphenicol will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• cimetidine

  Monitor Closely (1)cimetidine will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• ciprofloxacin

  Monitor Closely (1)ciprofloxacin will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• clarithromycin

  Monitor Closely (1)clarithromycin will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Modify Therapy/Monitor Closely.Minor (1)ethinylestradiol will increase the level or effect of clarithromycin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• clindamycin

  Monitor Closely (1)clindamycin will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• clobazam

  Monitor Closely (2)clobazam will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Clobazam is a weak CYP3A4 inducer; effectiveness of hormonal contraceptives may be diminished when given concurrently with clobazam. Additional non-hormonal forms of contraception are recommended.
  
  clobazam will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Clobazam is a weak CYP3A4 inducer; effectiveness of hormonal contraceptives may be diminished when given concurrently with clobazam. Additional non-hormonal forms of contraception are recommended.

• clomipramine

  Minor (1)ethinylestradiol will increase the level or effect of clomipramine by affecting hepatic enzyme CYP1A2 metabolism. Minor/Significance Unknown.

• clonazepam

  Monitor Closely (1)ethinylestradiol will increase the level or effect of clonazepam by Mechanism: decreasing metabolism. Use Caution/Monitor. Ethinyl estradiol may inhibit the clearance of benzodiazepines that undergo oxidation, thereby increasing serum concentrations of concomitantly administered benzodiazepines.

• conivaptan

  Serious - Use Alternative (1)conivaptan will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• crofelemer

  Monitor Closely (1)crofelemer increases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Crofelemer has the potential to inhibit CYP3A4 at concentrations expected in the gut; unlikely to inhibit systemically because minimally absorbed.

• cyclophosphamide

  Minor (2)cyclophosphamide will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
  
  cyclophosphamide will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• cyclosporine

  Monitor Closely (2)ethinylestradiol increases levels of cyclosporine by unknown mechanism. Use Caution/Monitor.
  
  levonorgestrel oral, cyclosporine. Either increases levels of the other by decreasing metabolism. Use Caution/Monitor. Combined oral contraceptives containing EE may inhibit the metabolism and increase plasma concentrations of cyclosporine.

• dabrafenib

  Monitor Closely (2)dabrafenib will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.
  
  dabrafenib will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely.

• dalteparin

  Serious - Use Alternative (1)levonorgestrel oral, dalteparin. Either decreases effects of the other by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Risk of thromboembolic disorders.

• darunavir

  Monitor Closely (1)darunavir will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Significant changes (increase or decrease) can occur in estrogen plasma levels. Efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• dasatinib

  Monitor Closely (1)ethinylestradiol will increase the level or effect of dasatinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• deferasirox

  Monitor Closely (1)deferasirox will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• demeclocycline

  Monitor Closely (1)demeclocycline will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• desipramine

  Minor (1)ethinylestradiol, desipramine. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Oxidative metabolism of TCAs may be decreased by ethinyl estradiol. Increased antidepressant serum concentrations may occur. Potential for increased TCA adverse effects.

• dexamethasone

  Monitor Closely (1)dexamethasone decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)dexamethasone will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• diazepam

  Monitor Closely (1)ethinylestradiol will increase the level or effect of diazepam by Mechanism: decreasing metabolism. Use Caution/Monitor. Ethinyl estradiol may inhibit the clearance of benzodiazepines that undergo oxidation, thereby increasing serum concentrations of concomitantly administered benzodiazepines.

• dicloxacillin

  Monitor Closely (1)dicloxacillin will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• dosulepin

  Minor (1)ethinylestradiol, dosulepin. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Oxidative metabolism of TCAs may be decreased by ethinyl estradiol. Increased antidepressant serum concentrations may occur. Potential for increased TCA adverse effects.

• doxepin

  Minor (1)ethinylestradiol, doxepin. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Oxidative metabolism of TCAs may be decreased by ethinyl estradiol. Increased antidepressant serum concentrations may occur. Potential for increased TCA adverse effects.

• doxycycline

  Monitor Closely (1)doxycycline will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• duloxetine

  Minor (1)ethinylestradiol will increase the level or effect of duloxetine by affecting hepatic enzyme CYP1A2 metabolism. Minor/Significance Unknown.

• efavirenz

  Monitor Closely (1)efavirenz decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)efavirenz will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• elagolix

  Monitor Closely (2)elagolix decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Elagolix is a weak-to-moderate CYP3A4 inducer. Monitor CYP3A substrates if coadministered. Consider increasing CYP3A substrate dose if needed.
  
  elagolix will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Elagolix is a weak-to-moderate CYP3A4 inducer. Monitor CYP3A substrates if coadministered. Consider increasing CYP3A substrate dose if needed.Serious - Use Alternative (2)levonorgestrel oral decreases effects of elagolix by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Based on the mechanism of action of elagolix, estrogen-containing contraceptives are expected to reduce elagolix efficacy. Effects of progestin-only contraceptives on the efficacy of elagolix is unknown. Advise women to use nonhormonal contraceptives during treatment with elagolix and for 1 week after discontinuing elagolix.
  
  ethinylestradiol decreases effects of elagolix by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Based on the mechanism of action of elagolix, estrogen-containing contraceptives are expected to reduce elagolix efficacy. Effects of progestin-only contraceptives on the efficacy of elagolix is unknown. Advise women to use nonhormonal contraceptives during treatment with elagolix and for 1 week after discontinuing elagolix.

• eltrombopag

  Monitor Closely (1)ethinylestradiol will increase the level or effect of eltrombopag by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.

• elvitegravir

  Serious - Use Alternative (1)elvitegravir will decrease the level or effect of ethinylestradiol by unknown mechanism. Avoid or Use Alternate Drug. Consider alternative nonhormonal methods of contraception to add or replace combination oral contraceptive

• elvitegravir/cobicistat/emtricitabine/tenofovir DF

  Monitor Closely (1)elvitegravir/cobicistat/emtricitabine/tenofovir DF increases levels of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Cobicistat is a CYP3A4 inhibitor; contraindicated with CYP3A4 substrates for which elevated plasma concentrations are associated with serious and/or life-threatening events.

• enasidenib

  Minor (2)enasidenib, levonorgestrel oral. unknown mechanism. Minor/Significance Unknown. Coadministration of enasidenib may increase or decrease the concentrations of combined hormonal contraceptives. Clinical significance of this interaction is unknown.
  
  enasidenib, ethinylestradiol. unknown mechanism. Minor/Significance Unknown. Coadministration of enasidenib may increase or decrease the concentrations of combined hormonal contraceptives. Clinical significance of this interaction is unknown.

• encorafenib

  Monitor Closely (2)encorafenib, levonorgestrel oral. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Encorafenib both inhibits and induces CYP3A4 at clinically relevant plasma concentrations. Coadministration of encorafenib with sensitive CYP3A4 substrates may result in increased toxicity or decreased efficacy of these agents.
  
  encorafenib will increase the level or effect of ethinylestradiol by Other (see comment). Modify Therapy/Monitor Closely. Encorafenib (a BCRP inhibitor) may increase the concentration and toxicities of BCRP substrates. Closely monitor for signs and symptoms of increased exposure and consider adjusting the dose of these substrates.Serious - Use Alternative (1)encorafenib will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of encorafenib with hormonal contraceptives (CYP3A4 substrates) can result in decreased concentrations and loss of hormonal contraceptive efficacy. Since encorafenib can cause fetal harm, advise women of childbearing potential to use a highly effective nonhormonal contraceptive during treatment and for 2 weeks after final encorafenib dose.

• enoxaparin

  Serious - Use Alternative (2)levonorgestrel oral, enoxaparin. Either decreases effects of the other by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Risk of thromboembolic disorders.
  
  ethinylestradiol decreases effects of enoxaparin by pharmacodynamic antagonism. Contraindicated. Risk of thromboembolic disorders.

• enzalutamide

  Monitor Closely (1)enzalutamide decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)enzalutamide will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• eplerenone

  Minor (1)ethinylestradiol will increase the level or effect of eplerenone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• erythromycin base

  Monitor Closely (1)erythromycin base will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor. Antibiotics may decrease hormonal contraceptive efficacy.

• erythromycin ethylsuccinate

  Monitor Closely (1)erythromycin ethylsuccinate will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor. Antibiotics may decrease hormonal contraceptive efficacy.

• erythromycin lactobionate

  Monitor Closely (1)erythromycin lactobionate will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor. Antibiotics may decrease hormonal contraceptive efficacy.

• erythromycin stearate

  Monitor Closely (1)erythromycin stearate will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor. Antibiotics may decrease hormonal contraceptive efficacy.

• eslicarbazepine acetate

  Serious - Use Alternative (2)eslicarbazepine acetate will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Use additional or alternative nonhormonal birth control.
  
  eslicarbazepine acetate will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Use additional or alternative nonhormonal birth control.

• etravirine

  Monitor Closely (2)etravirine will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.
  
  etravirine decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• exemestane

  Serious - Use Alternative (1)ethinylestradiol decreases effects of exemestane by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Exemestane should not be given concurrently with any estrogens or estrogen-containing products.

• exenatide injectable solution

  Monitor Closely (2)levonorgestrel oral, exenatide injectable solution. Other (see comment). Use Caution/Monitor. Comment: Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. The effect of exenatide to slow gastric emptying may reduce the extent and rate of oral medications that require rapid GI absorption. Advise patients to take oral contraceptives at least 1 hr before exenatide. .
  
  ethinylestradiol, exenatide injectable solution. Other (see comment). Use Caution/Monitor. Comment: Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. The effect of exenatide to slow gastric emptying may reduce the extent and rate of oral medications that require rapid GI absorption. Advise patients to take oral contraceptives at least 1 hr before exenatide. .

• exenatide injectable suspension

  Monitor Closely (2)ethinylestradiol, exenatide injectable suspension. Other (see comment). Use Caution/Monitor. Comment: Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. The effect of exenatide to slow gastric emptying may reduce the extent and rate of oral medications that require rapid GI absorption. Advise patients to take oral contraceptives at least 1 hr before exenatide.
  
  levonorgestrel oral, exenatide injectable suspension. Other (see comment). Use Caution/Monitor. Comment: Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. The effect of exenatide to slow gastric emptying may reduce the extent and rate of oral medications that require rapid GI absorption. Advise patients to take oral contraceptives at least 1 hr before exenatide.

• fedratinib

  Monitor Closely (2)fedratinib will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP3A4 substrates as necessary.
  
  fedratinib will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP3A4 substrates as necessary.Serious - Use Alternative (1)ethinylestradiol will increase the level or effect of fedratinib by Other (see comment). Avoid or Use Alternate Drug. Avoid coadministration of fedratinib (a CYP3A4 and CYP2C19 substrate) with dual CYP3A4 and CYP2C19 inhibitor. Effect of coadministration of a dual CYP3A4 and CYP2C19 inhibitor with fedratinib has not been studied.

• felbamate

  Monitor Closely (1)felbamate decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Minor (1)felbamate decreases levels of ethinylestradiol by unknown mechanism. Minor/Significance Unknown.

• fexinidazole

  Serious - Use Alternative (2)fexinidazole will increase the level or effect of ethinylestradiol by affecting hepatic enzyme CYP2E1 metabolism. Avoid or Use Alternate Drug. Fexinidazole inhibits CYP3A4. Coadministration may increase risk for adverse effects of CYP3A4 substrates.
  
  fexinidazole will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Fexinidazole inhibits CYP3A4. Coadministration may increase risk for adverse effects of CYP3A4 substrates.

• fezolinetant

  Contraindicated (1)ethinylestradiol will increase the level or effect of fezolinetant by affecting hepatic enzyme CYP1A2 metabolism. Contraindicated. Fezolinetant AUC and peak plasma concentration are increased if coadministered with drugs that are weak, moderate, or strong CYP1A2 inhibitors

• finerenone

  Monitor Closely (1)ethinylestradiol will increase the level or effect of finerenone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Monitor serum potassium during initiation and dosage adjustment of either finererone or weak CYP3A4 inhibitors. Adjust finererone dosage as needed.

• flibanserin

  Monitor Closely (1)ethinylestradiol will increase the level or effect of flibanserin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Increased flibanserin adverse effects may occur if coadministered with multiple weak CYP3A4 inhibitors.

• fluconazole

  Monitor Closely (1)fluconazole will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• fluvoxamine

  Monitor Closely (1)ethinylestradiol will increase the level or effect of fluvoxamine by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.

• fondaparinux

  Serious - Use Alternative (1)levonorgestrel oral, fondaparinux. Either decreases effects of the other by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Risk of thromboembolic disorders.

• fosamprenavir

  Serious - Use Alternative (1)fosamprenavir, ethinylestradiol. unspecified interaction mechanism. Avoid or Use Alternate Drug. Coadministration may decrease amprenavir AUC, and may lead to loss of virologic response. Coadministration of fosamprenavir with ethinyl estradiol may alter hormone levels. Alternative methods of nonhormonal contraception are recommended.

• fosphenytoin

  Monitor Closely (1)fosphenytoin decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• fostemsavir

  Monitor Closely (1)fostemsavir will increase the level or effect of ethinylestradiol by Other (see comment). Modify Therapy/Monitor Closely. Fostemsavir inhibits BCRP transporters. If possible, avoid coadministration or modify dose of BCRP substrate coadministered with fostemsavir. Do not ethinyl estradiol dose of exceed 30 mcg/day.

• frovatriptan

  Minor (1)ethinylestradiol will increase the level or effect of frovatriptan by affecting hepatic enzyme CYP1A2 metabolism. Minor/Significance Unknown.

• gemifloxacin

  Monitor Closely (1)gemifloxacin will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• grapefruit

  Monitor Closely (1)grapefruit will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• green tea

  Monitor Closely (1)ethinylestradiol increases levels of green tea by decreasing elimination. Use Caution/Monitor.

• griseofulvin

  Monitor Closely (1)griseofulvin decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)griseofulvin will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• hemin

  Monitor Closely (1)ethinylestradiol decreases effects of hemin by pharmacodynamic antagonism. Use Caution/Monitor. Drugs that increase delta-aminolevulinic acid synthetase may decrease hemin effect.

• heparin

  Serious - Use Alternative (2)levonorgestrel oral, heparin. Either decreases effects of the other by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Risk of thromboembolic disorders.
  
  ethinylestradiol decreases effects of heparin by pharmacodynamic antagonism. Contraindicated. Risk of thromboembolic disorders.

• hyaluronidase

  Monitor Closely (1)ethinylestradiol decreases effects of hyaluronidase by Other (see comment). Use Caution/Monitor. Comment: Estrogens, when given in large systemic doses, may render tissues partially resistant to the action of hyaluronidase. Patients may require larger amounts of hyaluronidase for equivalent dispersing effect.

• idelalisib

  Serious - Use Alternative (2)idelalisib will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Idelalisib is a strong CYP3A inhibitor; avoid coadministration with sensitive CYP3A substrates
  
  idelalisib will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Idelalisib is a strong CYP3A inhibitor; avoid coadministration with sensitive CYP3A substrates

• iloperidone

  Monitor Closely (2)iloperidone increases levels of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Iloperidone is a time-dependent CYP3A inhibitor and may lead to increased plasma levels of drugs predominantly eliminated by CYP3A4.
  
  iloperidone increases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Iloperidone is a time-dependent CYP3A inhibitor and may lead to increased plasma levels of drugs predominantly eliminated by CYP3A4.

• imipramine

  Minor (1)ethinylestradiol, imipramine. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Oxidative metabolism of TCAs may be decreased by ethinyl estradiol. Increased antidepressant serum concentrations may occur. Potential for increased TCA adverse effects.

• indinavir

  Serious - Use Alternative (1)indinavir, ethinylestradiol. Other (see comment). Avoid or Use Alternate Drug. Comment: Significant changes (increase or decrease) can occur in estrogen plasma levels. Efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended. .

• insulin aspart

  Monitor Closely (1)ethinylestradiol decreases effects of insulin aspart by pharmacodynamic antagonism. Use Caution/Monitor. Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. Monitor for glycemic control in diabetic patients.

• insulin degludec

  Monitor Closely (2)levonorgestrel oral decreases effects of insulin degludec by pharmacodynamic antagonism. Use Caution/Monitor. Progestins may impair glucose tolerance.
  
  ethinylestradiol decreases effects of insulin degludec by pharmacodynamic antagonism. Use Caution/Monitor. Estrogens may impair glucose tolerance.

• insulin degludec/insulin aspart

  Monitor Closely (2)ethinylestradiol decreases effects of insulin degludec/insulin aspart by pharmacodynamic antagonism. Use Caution/Monitor. Estrogens may impair glucose tolerance.
  
  levonorgestrel oral decreases effects of insulin degludec/insulin aspart by pharmacodynamic antagonism. Use Caution/Monitor. Progestins may impair glucose tolerance.

• insulin detemir

  Monitor Closely (1)ethinylestradiol decreases effects of insulin detemir by pharmacodynamic antagonism. Use Caution/Monitor. Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. Monitor for glycemic control in diabetic patients.

• insulin glargine

  Monitor Closely (1)ethinylestradiol decreases effects of insulin glargine by pharmacodynamic antagonism. Use Caution/Monitor. Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. Monitor for glycemic control in diabetic patients.

• insulin glulisine

  Monitor Closely (1)ethinylestradiol decreases effects of insulin glulisine by pharmacodynamic antagonism. Use Caution/Monitor. Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. Monitor for glycemic control in diabetic patients.

• insulin inhaled

  Monitor Closely (2)levonorgestrel oral decreases effects of insulin inhaled by pharmacodynamic antagonism. Use Caution/Monitor. Progestins may impair glucose tolerance.
  
  ethinylestradiol decreases effects of insulin inhaled by pharmacodynamic antagonism. Use Caution/Monitor. Estrogens may impair glucose tolerance.

• insulin lispro

  Monitor Closely (1)ethinylestradiol decreases effects of insulin lispro by pharmacodynamic antagonism. Use Caution/Monitor. Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. Monitor for glycemic control in diabetic patients.

• insulin NPH

  Monitor Closely (1)ethinylestradiol decreases effects of insulin NPH by pharmacodynamic antagonism. Use Caution/Monitor. Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. Monitor for glycemic control in diabetic patients.

• insulin regular human

  Monitor Closely (1)ethinylestradiol decreases effects of insulin regular human by pharmacodynamic antagonism. Use Caution/Monitor. Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. Monitor for glycemic control in diabetic patients.

• isavuconazonium sulfate

  Monitor Closely (1)ethinylestradiol will increase the level or effect of isavuconazonium sulfate by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (2)isavuconazonium sulfate will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  isavuconazonium sulfate will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• istradefylline

  Monitor Closely (2)istradefylline will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Istradefylline 40 mg/day increased peak levels and AUC of CYP3A4 substrates in clinical trials. This effect was not observed with istradefylline 20 mg/day. Consider dose reduction of sensitive CYP3A4 substrates.
  
  istradefylline will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Istradefylline 40 mg/day increased peak levels and AUC of CYP3A4 substrates in clinical trials. This effect was not observed with istradefylline 20 mg/day. Consider dose reduction of sensitive CYP3A4 substrates.

• itraconazole

  Monitor Closely (1)itraconazole will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inhibitors such as itraconazole may increase plasma hormone levels.

• ivosidenib

  Monitor Closely (1)ivosidenib will decrease the level or effect of levonorgestrel oral by unspecified interaction mechanism. Modify Therapy/Monitor Closely. Coadministration of ivosidenib may decrease the concentrations of hormonal contraceptives, consider alternative methods of contraception in patients receiving ivosidenib. Serious - Use Alternative (1)ivosidenib will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of sensitive CYP3A4 substrates with ivosidenib or replace with alternate therapies. If coadministration is unavoidable, monitor patients for loss of therapeutic effect of these drugs.

• ketoconazole

  Monitor Closely (1)ketoconazole will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inhibitors such as ketoconazole may increase plasma hormone levels.

• lamotrigine

  Monitor Closely (2)levonorgestrel oral will decrease the level or effect of lamotrigine by increasing hepatic clearance. Use Caution/Monitor. Combination oral contraceptives have been shown to significantly decrease plasma concentrations of lamotrigine, likely due to induction of lamotrigine glucuronidation.
  
  ethinylestradiol decreases levels of lamotrigine by increasing hepatic clearance. Use Caution/Monitor. Combination oral contraceptives have been shown to significantly decrease plasma concentrations of lamotrigine, likely due to induction of lamotrigine glucuronidation.

• lapatinib

  Monitor Closely (1)ethinylestradiol will increase the level or effect of lapatinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• larotrectinib

  Minor (2)larotrectinib will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.
  
  larotrectinib will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• lemborexant

  Monitor Closely (1)ethinylestradiol will increase the level or effect of lemborexant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Lower nightly dose of lemborexant recommended if coadministered with weak CYP3A4 inhibitors. See drug monograph for specific dosage modification.

• lenacapavir

  Monitor Closely (2)lenacapavir will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Lencapavir (a moderate CYP3A4 inhibitor) may increase CYP3A4 substrates initiated within 9 months after last SC dose of lenacapavir, which may increase potential risk of adverse reactions of CYP3A4 substrates.
  
  lenacapavir will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Lencapavir may increase CYP3A4 substrates initiated within 9 months after last SC dose of lenacapavir, which may increase potential risk of adverse reactions of CYP3A4 substrates.

• leniolisib

  Serious - Use Alternative (1)leniolisib will increase the level or effect of ethinylestradiol by Other (see comment). Avoid or Use Alternate Drug. Leniolisib, a BCRP inhibitor, may increase systemic exposure of BCRP substrates

• lesinurad

  Serious - Use Alternative (2)lesinurad decreases effects of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Use additional methods of nonhormonal contraception. Do not rely on hormonal contraception alone when taking lesinurad.
  
  lesinurad decreases effects of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Use additional methods of nonhormonal contraception. Do not rely on hormonal contraception alone when taking lesinurad.

• letrozole

  Serious - Use Alternative (1)ethinylestradiol decreases effects of letrozole by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Letrozole should not be given concurrently with any estrogens or estrogen-containing products.

• levofloxacin

  Monitor Closely (1)levofloxacin will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• levoketoconazole

  Monitor Closely (1)levoketoconazole will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. CYP3A4 inhibitors such as ketoconazole may increase plasma hormone levels.Minor (1)levoketoconazole will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• liraglutide

  Monitor Closely (2)ethinylestradiol decreases effects of liraglutide by pharmacodynamic antagonism. Use Caution/Monitor. Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. Monitor for glycemic control in diabetic patients.
  
  levonorgestrel oral decreases effects of liraglutide by pharmacodynamic antagonism. Use Caution/Monitor. Oral contraceptives may decrease hypoglycemic effects of antidiabetics by impairing glucose tolerance. Monitor for glycemic control in diabetic patients.

• lixisenatide (DSC)

  Monitor Closely (1)lixisenatide (DSC) will decrease the level or effect of ethinylestradiol by inhibition of GI absorption. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. GLP1 agonists delay gastric emptying, which may affect absorption of concomitantly administered oral medications. Oral contraceptives should be taken at least 1 hr before lixisenatide administration or 11 hr after lixisenatide.

• lomitapide

  Monitor Closely (1)ethinylestradiol increases levels of lomitapide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Lomitapide dose should not exceed 30 mg/day.

• lonafarnib

  Serious - Use Alternative (1)ethinylestradiol will increase the level or effect of lonafarnib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of lonafarnib (a sensitive CYP3A substrate) with weak CYP3A inhibitors is unavoidable, reduce to, or continue lonafarnib at starting dose. Closely monitor for arrhythmias and events (eg, syncope, heart palpitations) since lonafarnib effect on QT interval is unknown.

• lonapegsomatropin

  Monitor Closely (2)ethinylestradiol will decrease the level or effect of lonapegsomatropin by Other (see comment). Use Caution/Monitor. Oral estrogens may reduce serum insulin-like growth factor-1 response to lonapegsomatropin. Patients receiving oral estrogen replacement may require higher lonapegsomatropin dosages.
  
  ethinylestradiol will decrease the level or effect of lonapegsomatropin by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Oral estrogens may reduce serum insulin-like growth factor I (IGF-1) response to growth hormone (GH) analogs. Higher GH dose may be required

• lopinavir

  Serious - Use Alternative (2)lopinavir will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  lopinavir, ethinylestradiol. Other (see comment). Avoid or Use Alternate Drug. Comment: Significant changes (increase or decrease) can occur in estrogen plasma levels. Efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended. .

• lorlatinib

  Monitor Closely (1)lorlatinib will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)lorlatinib will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• lumacaftor/ivacaftor

  Serious - Use Alternative (1)lumacaftor/ivacaftor will decrease the level or effect of ethinylestradiol by unspecified interaction mechanism. Avoid or Use Alternate Drug. Avoid coadministration unless benefit outweighs risk. When coadministered, hormonal contraceptives are not a reliable method of effective birth control. Concomitant use may increase incidence of menstruation associated adverse effects (amenorrhea, dysmenorrhea, menorrhagia).

• lumefantrine

  Monitor Closely (1)lumefantrine will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• maraviroc

  Monitor Closely (1)levonorgestrel oral increases levels of maraviroc by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Potential for increased toxicity.

• mavacamten

  Serious - Use Alternative (2)mavacamten will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Progestin and ethinyl estradiol are CYP3A4 substrates. Mavacamten may decrease systemic exposures of ethinyl estradiol and progestin, which may lead to contraceptive failure or an increase in breakthrough bleeding. Advise patients to use a contraceptive method that is not affected by CYP450 enzyme induction (eg, intrauterine system) or add nonhormonal contraception (eg, condoms) during coadministration and for 4 months after last mavacamten dose.
  
  mavacamten will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Progestin and ethinyl estradiol are CYP3A4 substrates. Mavacamten may decrease systemic exposures of ethinyl estradiol and progestin, which may lead to contraceptive failure or an increase in breakthrough bleeding. Advise patients to use a contraceptive method that is not affected by CYP450 enzyme induction (eg, intrauterine system) or add nonhormonal contraception (eg, condoms) during coadministration and for 4 months after last mavacamten dose.

• metformin

  Monitor Closely (2)ethinylestradiol decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.
  
  levonorgestrel oral decreases effects of metformin by pharmacodynamic antagonism. Use Caution/Monitor.

• metronidazole

  Monitor Closely (1)metronidazole will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• metyrapone

  Serious - Use Alternative (1)ethinylestradiol decreases effects of metyrapone by unspecified interaction mechanism. Avoid or Use Alternate Drug. A subtherapeutic response to metyrapone can be seen in patients on estrogens, including oral contraceptives, that contain estrogen therapy. It may be advisable to discontinue estrogens prior to and during metyrapone administration.

• mexiletine

  Monitor Closely (1)ethinylestradiol will increase the level or effect of mexiletine by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.

• midazolam

  Monitor Closely (1)ethinylestradiol will increase the level or effect of midazolam by Mechanism: decreasing metabolism. Use Caution/Monitor. Ethinyl estradiol may inhibit the clearance of benzodiazepines that undergo oxidation, thereby increasing serum concentrations of concomitantly administered benzodiazepines.

• midazolam intranasal

  Monitor Closely (1)ethinylestradiol will increase the level or effect of midazolam intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of mild CYP3A4 inhibitors with midazolam intranasal may cause higher midazolam systemic exposure, which may prolong sedation.

• mifepristone

  Monitor Closely (2)mifepristone decreases effects of levonorgestrel oral by pharmacodynamic antagonism. Use Caution/Monitor. Backup contraceptive method recommended.
  
  mifepristone decreases effects of ethinylestradiol by pharmacodynamic antagonism. Use Caution/Monitor. Backup contraceptive method recommended.Serious - Use Alternative (2)mifepristone will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated.
  
  mifepristone will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• mineral oil

  Minor (1)mineral oil decreases levels of ethinylestradiol by inhibition of GI absorption. Applies only to oral form of both agents. Minor/Significance Unknown.

• minocycline

  Monitor Closely (1)minocycline will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• mitotane

  Monitor Closely (2)mitotane decreases levels of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Mitotane is a strong inducer of cytochrome P-4503A4; monitor when coadministered with CYP3A4 substrates for possible dosage adjustments.
  
  mitotane decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Mitotane is a strong inducer of cytochrome P-4503A4; monitor when coadministered with CYP3A4 substrates for possible dosage adjustments.

• mobocertinib

  Serious - Use Alternative (2)mobocertinib will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of mobocertinib with hormonal contraceptives may lead to contraceptive failure or increased breakthrough bleeding. Advise females of reproductive potential to use effective non-hormonal contraception.
  
  mobocertinib will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of mobocertinib with hormonal contraceptives may lead to contraceptive failure or increased breakthrough bleeding. Advise females of reproductive potential to use effective non-hormonal contraception.

• momelotinib

  Monitor Closely (1)momelotinib increases toxicity of ethinylestradiol by plasma protein binding competition. Modify Therapy/Monitor Closely. Momelotinib (BCRP inhibitor) may increase exposure of BCRP substrates, which may increase the risk of BCRP substrate adverse reactions. Dose adjustment of other BCRP substrates may necessary.

• moxifloxacin

  Monitor Closely (1)moxifloxacin will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• mycophenolate

  Monitor Closely (1)mycophenolate decreases levels of levonorgestrel oral by unspecified interaction mechanism. Use Caution/Monitor. Consider additional birth control methods during mycophenolate administration.Serious - Use Alternative (1)mycophenolate decreases effects of ethinylestradiol by unknown mechanism. Avoid or Use Alternate Drug. Patients should consider using an alternative or additional form of contraception.

• nafcillin

  Monitor Closely (2)nafcillin will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
  
  nafcillin decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• naratriptan

  Minor (1)ethinylestradiol increases effects of naratriptan by unspecified interaction mechanism. Minor/Significance Unknown. The clinical implication of these interactions is unknown.

• nefazodone

  Serious - Use Alternative (1)nefazodone will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.Minor (1)nefazodone will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• nelfinavir

  Serious - Use Alternative (2)nelfinavir will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  nelfinavir, ethinylestradiol. Other (see comment). Avoid or Use Alternate Drug. Comment: Significant changes (increase or decrease) can occur in estrogen plasma levels. Efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended. .

• neomycin PO

  Monitor Closely (1)neomycin PO will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• nevirapine

  Monitor Closely (1)nevirapine decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)nevirapine will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• nicardipine

  Monitor Closely (1)ethinylestradiol will increase the level or effect of nicardipine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• nilotinib

  Monitor Closely (1)ethinylestradiol will increase the level or effect of nilotinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• nirmatrelvir

  Monitor Closely (1)nirmatrelvir will decrease the level or effect of ethinylestradiol by increasing metabolism. Modify Therapy/Monitor Closely. Consider using additional nonhormonal contraceptive method for remainder of cycle. Mechanism unknown, but possibly by ritonavir CYP2C9 or CYP1A2 induction.

• nirmatrelvir/ritonavir

  Monitor Closely (1)nirmatrelvir/ritonavir will decrease the level or effect of ethinylestradiol by increasing metabolism. Modify Therapy/Monitor Closely. Consider using additional nonhormonal contraceptive method for remainder of cycle. Mechanism unknown, but possibly by ritonavir CYP2C9 or CYP1A2 induction.

• nitrofurantoin

  Monitor Closely (1)nitrofurantoin will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• nortriptyline

  Minor (1)ethinylestradiol, nortriptyline. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Oxidative metabolism of TCAs may be decreased by ethinyl estradiol. Increased antidepressant serum concentrations may occur. Potential for increased TCA adverse effects.

• ofloxacin

  Monitor Closely (1)ofloxacin will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• olanzapine

  Monitor Closely (1)ethinylestradiol will increase the level or effect of olanzapine by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.

• omaveloxolone

  Serious - Use Alternative (2)omaveloxolone will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Omaveloxolone may reduce efficacy of hormonal contraceptives (eg, pill, patch, ring), implants, and progestin-only pills owing to weak CYP3A4 induction.
  
  omaveloxolone will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Omaveloxolone may reduce efficacy of hormonal contraceptives (eg, pill, patch, ring), implants, and progestin-only pills owing to weak CYP3A4 induction.

• ombitasvir/paritaprevir/ritonavir & dasabuvir (DSC)

  Contraindicated (2)ombitasvir/paritaprevir/ritonavir & dasabuvir (DSC), ethinylestradiol. unspecified interaction mechanism. Contraindicated. Potential for increased ALT; contraceptive failure may occur when coadministered with protease inhibitors (ritonavir).
  
  ethinylestradiol, ombitasvir/paritaprevir/ritonavir & dasabuvir (DSC). Either increases toxicity of the other by unspecified interaction mechanism. Contraindicated. ALT elevations >5 x ULN (including some >20 x ULN) observed in clinical trials when ethinyl estradiol was coadministered with ombitasvir/paritaprevir/ritonavir, with or without dasabuvir. Discontinue ethinyl estradiol-containing medications before initiating ombitasvir/paritaprevir/ritonavir, and/or dasabuvir. Restart ethinyl estradiol containing medication ~2 weeks after hepatitis C combination drug regimen completed.

• oteseconazole

  Monitor Closely (1)oteseconazole will increase the level or effect of ethinylestradiol by Other (see comment). Modify Therapy/Monitor Closely. Otesezonale, a BCRP inhibitor, may increase the effects and risk of toxicities of BCRP substrates. Use lowest starting dose of BCRP substrate, or consider reducing BCRP substrate dose.

• oxcarbazepine

  Monitor Closely (1)oxcarbazepine decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)oxcarbazepine will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• paromomycin

  Monitor Closely (1)paromomycin will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• penicillin G aqueous

  Monitor Closely (1)penicillin G aqueous decreases levels of ethinylestradiol by increasing metabolism. Use Caution/Monitor. Risk of oral contraceptive failure.

• penicillin VK

  Monitor Closely (1)penicillin VK will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• pentobarbital

  Monitor Closely (1)pentobarbital decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)pentobarbital will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• perampanel

  Serious - Use Alternative (1)perampanel will decrease the level or effect of levonorgestrel oral by unspecified interaction mechanism. Avoid or Use Alternate Drug. Levonorgestrel levels reduced by 40% when coadministered with high dose perampanel (ie, 12 mg/day); effect on other progestins is unknown, consider back up contraception

• pexidartinib

  Serious - Use Alternative (1)levonorgestrel oral and pexidartinib both increase Other (see comment). Avoid or Use Alternate Drug. Pexidartinib can cause hepatotoxicity. Avoid coadministration of pexidartinib with other products know to cause hepatoxicity.

• phenindione

  Serious - Use Alternative (1)levonorgestrel oral, phenindione. Either decreases effects of the other by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Risk of thromboembolic disorders.

• phenobarbital

  Monitor Closely (1)phenobarbital decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)phenobarbital will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• phenytoin

  Monitor Closely (1)phenytoin decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)phenytoin will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• pioglitazone

  Monitor Closely (1)pioglitazone decreases levels of ethinylestradiol by unknown mechanism. Use Caution/Monitor.

• pitolisant

  Monitor Closely (1)pitolisant will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Pitolisant is a borderline/weak inducer of CYP3A4. Monitor sensitive CYP3A4 substrates for reduced effectiveness if coadministered.

• posaconazole

  Monitor Closely (1)posaconazole will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• pretomanid

  Serious - Use Alternative (1)levonorgestrel oral, pretomanid. Either increases toxicity of the other by Other (see comment). Avoid or Use Alternate Drug. Comment: Pretomanid regimen associated with hepatotoxicity. Avoid alcohol and hepatotoxic agents, including herbal supplements and drugs other than bedaquiline and linezolid.

• primidone

  Monitor Closely (1)primidone decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)primidone will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• protamine

  Serious - Use Alternative (1)levonorgestrel oral, protamine. Either decreases effects of the other by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Risk of thromboembolic disorders.

• protriptyline

  Minor (1)ethinylestradiol, protriptyline. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Oxidative metabolism of TCAs may be decreased by ethinyl estradiol. Increased antidepressant serum concentrations may occur. Potential for increased TCA adverse effects.

• quinidine

  Serious - Use Alternative (1)quinidine will increase the level or effect of ethinylestradiol by P-glycoprotein (MDR1) efflux transporter. Avoid or Use Alternate Drug.

• quinupristin/dalfopristin

  Monitor Closely (1)quinupristin/dalfopristin will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• ramelteon

  Monitor Closely (1)ethinylestradiol will increase the level or effect of ramelteon by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.Minor (1)ethinylestradiol will increase the level or effect of ramelteon by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• ranolazine

  Serious - Use Alternative (1)ethinylestradiol will increase the level or effect of ranolazine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• rasagiline

  Monitor Closely (1)ethinylestradiol will increase the level or effect of rasagiline by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor. Recommended dose of rasagiline is 0.5mg daily in combination with CYP1A2 inhibitors.

• ribociclib

  Monitor Closely (2)ribociclib will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
  
  ribociclib will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• rifabutin

  Monitor Closely (1)rifabutin decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)rifabutin will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• rifampin

  Monitor Closely (1)rifampin decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)rifampin will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• rifapentine

  Monitor Closely (1)rifapentine decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)rifapentine will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• ritonavir

  Serious - Use Alternative (3)ritonavir will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  ritonavir will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  ritonavir, ethinylestradiol. Other (see comment). Avoid or Use Alternate Drug. Comment: Significant changes (increase or decrease) can occur in estrogen plasma levels. Efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended. .

• romidepsin

  Monitor Closely (1)romidepsin decreases effects of ethinylestradiol by receptor binding competition. Use Caution/Monitor.

• ropinirole

  Monitor Closely (2)ethinylestradiol will increase the level or effect of ropinirole by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.
  
  ethinylestradiol increases levels of ropinirole by unspecified interaction mechanism. Use Caution/Monitor.

• rosuvastatin

  Minor (1)rosuvastatin increases levels of ethinylestradiol by unspecified interaction mechanism. Minor/Significance Unknown.

• rucaparib

  Monitor Closely (2)rucaparib will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust dosage of CYP3A4 substrates, if clinically indicated.
  
  rucaparib will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust dosage of CYP3A4 substrates, if clinically indicated.

• rufinamide

  Monitor Closely (1)rufinamide decreases effects of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Rufinamide is a weak inducer of the CYP 3A4 enzyme and can decrease exposure of drugs that are substrates of CYP3A4. .

• ruxolitinib

  Minor (1)ethinylestradiol will increase the level or effect of ruxolitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• ruxolitinib topical

  Minor (1)ethinylestradiol will increase the level or effect of ruxolitinib topical by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• saquinavir

  Serious - Use Alternative (2)saquinavir will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.
  
  saquinavir, ethinylestradiol. Other (see comment). Avoid or Use Alternate Drug. Comment: Significant changes (increase or decrease) can occur in estrogen plasma levels. Efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended. .

• secobarbital

  Monitor Closely (1)secobarbital will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)secobarbital will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• selegiline

  Monitor Closely (1)ethinylestradiol increases levels of selegiline by Other (see comment). Use Caution/Monitor. Comment: Oral contraceptives inhibit the N demethylatin of selegiline.

• selegiline transdermal

  Monitor Closely (1)ethinylestradiol increases levels of selegiline transdermal by Other (see comment). Use Caution/Monitor. Comment: Oral contraceptives inhibit the N demethylatin of selegiline.

• siltuximab

  Monitor Closely (2)siltuximab, ethinylestradiol. Other (see comment). Use Caution/Monitor. Comment: CYP450 activity in the liver is down regulated by infection and inflammation stimuli including cytokines (eg, IL-6); inhibition of IL-6 by siltuximab may restore CYP450 enzymatic activity; caution if coadministered with CYP substrates that have a narrow therapeutic index.
  
  siltuximab, levonorgestrel oral. Other (see comment). Use Caution/Monitor. Comment: CYP450 activity in the liver is down regulated by infection and inflammation stimuli including cytokines (eg, IL-6); inhibition of IL-6 by siltuximab may restore CYP450 enzymatic activity; caution if coadministered with CYP substrates that have a narrow therapeutic index.

• somapacitan

  Monitor Closely (1)ethinylestradiol will decrease the level or effect of somapacitan by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Oral estrogens may reduce serum insulin-like growth factor I (IGF-1) response to growth hormone (GH) analogs. Higher GH dose may be required

• somatrogon

  Monitor Closely (1)ethinylestradiol will decrease the level or effect of somatrogon by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Oral estrogens may reduce serum insulin-like growth factor I (IGF-1) response to growth hormone (GH) analogs. Higher GH dose may be required

• somatropin

  Monitor Closely (1)ethinylestradiol will decrease the level or effect of somatropin by pharmacodynamic antagonism. Modify Therapy/Monitor Closely. Oral estrogens may reduce serum insulin-like growth factor I (IGF-1) response to growth hormone (GH) analogs. Higher GH dose may be required

• St John's Wort

  Serious - Use Alternative (1)St John's Wort will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• stiripentol

  Monitor Closely (2)stiripentol, levonorgestrel oral. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Stiripentol is a CYP3A4 inhibitor and inducer. Monitor CYP3A4 substrates coadministered with stiripentol for increased or decreased effects. CYP3A4 substrates may require dosage adjustment.
  
  stiripentol, ethinylestradiol. affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Stiripentol is a CYP3A4 inhibitor and inducer. Monitor CYP3A4 substrates coadministered with stiripentol for increased or decreased effects. CYP3A4 substrates may require dosage adjustment.

• sugammadex sodium

  Serious - Use Alternative (2)sugammadex sodium decreases effects of ethinylestradiol by receptor binding competition. Avoid or Use Alternate Drug. In vitro binding studies showed that sugammadex may bind to progestogen, thereby decreasing progestogen exposure. Therefore, a sugammadex bolus dose is considered to be equivalent to missing dose(s) of hormonal contraceptives containing an estrogen or progestogen. If an oral contraceptive is taken on the same day of sugammadex, or the patient has a transdermal or implant hormonal contraceptive, the patient must use an additional, nonhormonal contraceptive method or back-up method of contraception (eg, condoms and spermicides) for the next 7 days.
  
  sugammadex sodium decreases effects of levonorgestrel oral by receptor binding competition. Avoid or Use Alternate Drug. In vitro binding studies showed that sugammadex may bind to progestogen, thereby decreasing progestogen exposure. Therefore, a sugammadex bolus dose is considered to be equivalent to missing dose(s) of hormonal contraceptives containing an estrogen or progestogen. If an oral contraceptive is taken on the same day of sugammadex, or the patient has a transdermal or implant hormonal contraceptive, the patient must use an additional, nonhormonal contraceptive method or back-up method of contraception (eg, condoms and spermicides) for the next 7 days.

• sulfadiazine

  Monitor Closely (1)sulfadiazine will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• sulfamethoxazole

  Monitor Closely (1)sulfamethoxazole will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• sulfisoxazole

  Monitor Closely (1)sulfisoxazole will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• tacrolimus

  Monitor Closely (1)ethinylestradiol will increase the level or effect of tacrolimus by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• tazemetostat

  Monitor Closely (3)tazemetostat will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
  
  ethinylestradiol will increase the level or effect of tazemetostat by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.
  
  tazemetostat will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• tecovirimat

  Monitor Closely (2)tecovirimat will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Tecovirimat is a weak CYP3A4 inducer. Monitor sensitive CYP3A4 substrates for effectiveness if coadministered.
  
  tecovirimat will decrease the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Tecovirimat is a weak CYP3A4 inducer. Monitor sensitive CYP3A4 substrates for effectiveness if coadministered.

• teriflunomide

  Monitor Closely (2)teriflunomide increases levels of levonorgestrel oral by unknown mechanism. Use Caution/Monitor.
  
  teriflunomide increases levels of ethinylestradiol by unknown mechanism. Use Caution/Monitor.

• tesamorelin

  Monitor Closely (1)tesamorelin will decrease the level or effect of levonorgestrel oral by altering metabolism. Use Caution/Monitor. Use alternative contraception

• tetracycline

  Monitor Closely (1)tetracycline will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• theophylline

  Monitor Closely (1)ethinylestradiol will increase the level or effect of theophylline by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor.

• ticarcillin

  Monitor Closely (1)ticarcillin will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• tigecycline

  Monitor Closely (1)tigecycline will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• tinidazole

  Monitor Closely (1)ethinylestradiol will increase the level or effect of tinidazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• tipranavir

  Serious - Use Alternative (1)tipranavir, ethinylestradiol. Other (see comment). Avoid or Use Alternate Drug. Comment: Significant changes (increase or decrease) can occur in estrogen plasma levels. Efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended. .

• tizanidine

  Monitor Closely (1)ethinylestradiol will increase the level or effect of tizanidine by affecting hepatic enzyme CYP1A2 metabolism. Use Caution/Monitor. Monitor for tizanidine adverse effects (eg, hypotension or bradycardia)Minor (1)ethinylestradiol increases levels of tizanidine by unspecified interaction mechanism. Minor/Significance Unknown.

• tolterodine

  Monitor Closely (1)ethinylestradiol will increase the level or effect of tolterodine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• topiramate

  Monitor Closely (1)topiramate decreases levels of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.Serious - Use Alternative (1)topiramate will decrease the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. The efficacy of hormonal contraceptives may be reduced. Use of a nonhormonal contraceptive is recommended.

• tranexamic acid oral

  Contraindicated (1)tranexamic acid oral, ethinylestradiol. Either increases toxicity of the other by pharmacodynamic synergism. Contraindicated. Coadministration of tranexamic acid oral and combination hormonal contraceptives increases thrombotic risk.

• trazodone

  Minor (1)ethinylestradiol, trazodone. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Oxidative metabolism of TCAs may be decreased by ethinyl estradiol. Increased antidepressant serum concentrations may occur. Potential for increased TCA adverse effects.

• triazolam

  Monitor Closely (1)ethinylestradiol will increase the level or effect of triazolam by Mechanism: decreasing metabolism. Use Caution/Monitor. Ethinyl estradiol may inhibit the clearance of benzodiazepines that undergo oxidation, thereby increasing serum concentrations of concomitantly administered benzodiazepines.

• trimethoprim

  Monitor Closely (1)trimethoprim will decrease the level or effect of ethinylestradiol by altering intestinal flora. Applies only to oral forms of hormone. Low risk of contraceptive failure. Use Caution/Monitor.

• trimipramine

  Minor (1)ethinylestradiol, trimipramine. Mechanism: unspecified interaction mechanism. Minor/Significance Unknown. Oxidative metabolism of TCAs may be decreased by ethinyl estradiol. Increased antidepressant serum concentrations may occur. Potential for increased TCA adverse effects.

• tucatinib

  Serious - Use Alternative (2)tucatinib will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid concomitant use of tucatinib with CYP3A substrates, where minimal concentration changes may lead to serious or life-threatening toxicities. If unavoidable, reduce CYP3A substrate dose according to product labeling.
  
  tucatinib will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid concomitant use of tucatinib with CYP3A substrates, where minimal concentration changes may lead to serious or life-threatening toxicities. If unavoidable, reduce CYP3A substrate dose according to product labeling.

• ursodiol

  Monitor Closely (1)ethinylestradiol decreases effects of ursodiol by pharmacodynamic antagonism. Use Caution/Monitor.

• valoctocogene roxaparvovec

  Monitor Closely (2)levonorgestrel oral and valoctocogene roxaparvovec both increase Other (see comment). Use Caution/Monitor. Medications that may cause hepatotoxicity when combined with valoctogene roxaparvovec may potentiate the risk of elevated liver enzymes. Closely monitor these medications and consider alternative medications in case of potential drug interactions.
  
  ethinylestradiol and valoctocogene roxaparvovec both increase Other (see comment). Use Caution/Monitor. Medications that may cause hepatotoxicity when combined with valoctogene roxaparvovec may potentiate the risk of elevated liver enzymes. Closely monitor these medications and consider alternative medications in case of potential drug interactions.

• valproic acid

  Monitor Closely (1)ethinylestradiol will decrease the level or effect of valproic acid by increasing elimination. Modify Therapy/Monitor Closely. May lead to increased seizure frequency

• voriconazole

  Monitor Closely (1)voriconazole will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• voxelotor

  Serious - Use Alternative (2)voxelotor will increase the level or effect of ethinylestradiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Voxelotor increases systemic exposure of sensitive CYP3A4 substrates. Avoid coadministration with sensitive CYP3A4 substrates with a narrow therapeutic index. Consider dose reduction of the sensitive CYP3A4 substrate(s) if unable to avoid.
  
  voxelotor will increase the level or effect of levonorgestrel oral by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Voxelotor increases systemic exposure of sensitive CYP3A4 substrates. Avoid coadministration with sensitive CYP3A4 substrates with a narrow therapeutic index. Consider dose reduction of the sensitive CYP3A4 substrate(s) if unable to avoid.