doxycycline (Rx)

Rickettsial Infections

Indicated for Rocky Mountain spotted fever, typhus fever and the typhus group, Q fever, rickettsialpox, and tick fevers caused by Rickettsiae

Day 1: 200 mg/day PO/IV divided BID (IV may be given qDay), THEN

Maintenance: 100-200 mg/day PO/IV qDay or divided q12hr (IV may be given qDay)

Sexually Transmitted Infections

Lymphogranuloma venereum, uncomplicated urethral, endocervical or rectal infections caused by Chlamydia trachomatis

• Uncomplicated urethral or endocervical infections

  • 100 mg PO BID or 200 mg PO qDay (delayed-release) x 7 days
  • For empiric therapy, give in combination with single dose of ceftriaxone if patient at high risk for gonorrhea, if follow up is a concern, or if local prevalence of gonorrhea elevated

• Rectal infections

  • Empiric therapy for acute proctitis or proctocolitis or pathogen-directed therapy for Chlamydia trachomatis (off-label): 100 mg PO BID x 7 days
  • For empiric therapy, give in combination with a single dose of ceftriaxone
  • Lymphogranuloma venereum: Extend duration to 21 days for presumptive therapy of lymphogranuloma venereum if patient has severe rectal symptoms (eg, bloody discharge, tenesmus, perianal ulcers or mucosal ulcers) and a positive rectal chlamydia or HIV infection

Nongonococcal urethritis caused by Ureaplasma urealyticum

• 100 mg PO BID x 7 day

Granuloma inguinale caused by Klebsiella granulomatis

• 100 mg PO BID x 3 weeks and until resolution of lesions
• Consider adding additional antibiotic if symptoms do not improve within first few days

Post-exposure prophylaxis (PEP) (Off-label)

• Postexposure prophylaxis after unprotected anal sex: 200 mg PO x 1 dose within 24-72 hr after sex among males who have sex with males and transgender women
• CDC is evaluating doxycycline post-exposure prophylaxis (doxy-PEP) to prevent gonorrhea, chlamydia, and syphilis

Syphilis caused by Treponema pallidum (when penicillin contraindicated)

• Syphilis (<1 year duration): 100 mg PO BID for 2 weeks
• Syphilis (≥1 year duration): 100 mg PO BID for 4 weeks
• Close serologic and clinical follow-up warranted as data are limited

Uncomplicated gonorrhea caused by Neisseria gonorrhoeae

• Although included in the manufacturer's prescribing information as an FDA-approved use, doxycycline is not recommended for treatment of uncomplicated gonorrhea owing to resistance
• CDC Sexually Transmitted Infections Treatment Guidelines, 2021

Respiratory Tract Infections

Indications

• Respiratory tract infections caused by Mycoplasma pneumoniae
• Psittacosis (ornithosis) caused by Chlamydophila psittaci
• Indicated for respiratory tract infections caused by the following microorganisms, when bacteriological testing indicates appropriate susceptibility to drug: Haemophilus influenzae, Klebsiella species, Streptococcus pneumoniae

Dosage

• Day 1: 200 mg/day PO/IV divided BID (IV may be given qDay), THEN
• Maintenance: 100-200 mg/day PO/IV qDay or divided q12hr PO/IV (IV may be given qDay)

Specific Bacterial Infections

Indications

• Relapsing fever due to Borrelia recurrentis
• Plague due to Yersinia pestis
• Tularemia due to Francisella tularensis
• Cholera caused by Vibrio cholerae
• Campylobacter fetus infections caused by Campylobacter fetus
• Brucellosis due to Brucella species (in conjunction with streptomycin)
• Bartonellosis due to Bartonella bacilliformis
• Gram negative microorganisms (eg, Escherichia coli, Enterobacter aerogenes, Shigella species, Acinetobacter species, urinary tract infections caused by Klebsiella species)

Dosage

• Day 1: 200 mg/day PO/IV divided BID (IV may be given qDay), THEN
• Maintenance: 100-200 mg/day PO/IV qDay or divided q12hr PO/IV (IV may be given qDay)

Ophthalmic infections

Indicated for trachoma caused by Chlamydia trachomatis, although the infectious agent is not always eliminated as judged by immunofluorescence

Inclusion conjunctivitis caused by Chlamydia trachomatis

Anthrax

Indicated for anthrax due to Bacillus anthracis, including inhalational anthrax (postexposure)

100 mg PO BID for 60 days

Select Infections When Penicillin is Contraindicated

When penicillin is contraindicated, doxycycline is an alternative treatment of the following infections:

• Yaws caused by Treponema pallidum subspecies pertenue
• Vincent’s infection caused by Fusobacterium fusiforme
• Actinomycosis caused by Actinomyces israelii. Infections caused by Clostridium species

Acute Intestinal Amebiasis

Indicated as adjunctive therapy for acute intestinal amebiasis

Day 1: 200 mg/day PO/IV divided BID (IV may be given qDay), THEN

Maintenance: 100-200 mg/day PO/IV qDay or divided q12hr (IV may be given qDay)

Acne Vulgaris

Indicated as adjunctive therapy for severe acne

Immediate-release: 50-100 mg PO BID or 100 mg PO qDay

Extended-release: 100 mg PO BID on day 1, then 100 mg qDay

Low-dose (subantimicrobial) dosing: 20 mg PO BID (immediate-release) or 40 mg PO qDay (delayed-release)

Rosacea

Oracea only

Indicated for treatment of only inflammatory lesions (papules and pustules) of rosacea in adults

20 mg once daily (delayed release; Oracea) or 20 mg twice daily (immediate release)

Malaria

Indicated for prophylaxis of malaria due to Plasmodium falciparum in short-term travelers (<4 months) to areas with chloroquine and/or pyrimethamine-sulfadoxine resistant strains

Prophylaxis: 100 mg PO qDay; begin taking 1-2 days before travel and continue daily during travel and for 4 weeks after traveler leaves malaria infested area

Severe infection (off-label): 100 mg PO/IV q12hr x 7 days with 3-7 days quinidine gluconate

Uncomplicated infection (off-label): 100 mg PO q12hr x 7 days with 3-7 days quinine sulfate depending on region

Equivalent dose of Doryx MPC is 120 mg

Periodontal Disease

Atridox: Apply subgingivally; dose depends on size, shape, and number of pockets treated

Dosing Considerations

Susceptible organisms

• Propionibacterium acnes, Actinomyces israelii, Acinetobacter spp, Bacillus anthracis, Bacteroides spp., Bartonella bacilliformis, Bartonella henselae, Bartonella quintana, Borrelia recurrentis, Brucella spp, Campylobacter jejuni, Chlamydia psittaci, Chlamydia trachomatis, Capnocytophaga canimorsus, Citrobacter diversus, Citrobacter freundii, Escherichia coli, Eikenella corrodens, Francisella tularensis, Haemophilus ducreyi, Helicobacter pylori, Klebsiella granulomatis, Klebsiella pneumoniae, Listeria monocytogenes, Mycoplasma hominis, Mycoplasma pneumoniae, Neisseria gonorrhoeae, Propionibacterium acnes, Rickettsiae, Shigella spp., MRSA, Staphylococcus saprophyticus, Streptococcus spp, Treponema pallidum, Ureaplasma urealyticum, Vibrio cholerae, Yersinia enterocolitica, Yersinia pestis, VRE, mycobacteria other than tuberculosis

General Dosing Guidelines

≤8 years: Not recommended for mild-to-moderate infections; may cause tooth discoloration and enamel hypoplasia during tooth development

>8 years, <45 Kg

• Load: 4.4 mg/kg/day PO/IV divided q12hr day 1  
• Maintenance: 2.2-4.4 mg/kg/day IV/PO qDay (may divide BID for higher doses)

• Doryx MPC

  • Severe or life-threatening infections (eg, anthrax, Rocky Mountain spotted fever): 2.6 mg/kg PO BID
  • Less severe infections: 5.3 mg/kg PO divided into 2 doses on day 1, then a maintenance dose of 2.6 mg/kg PO qDay

>8 years, ≥45 kg

• 100 mg PO q12hr or 50 mg PO q6hr on day 1, followed by maintenance dose of 100 mg/day as single dose or as 50 mg q12hr
• Doryx MPC: 120 mg PO q12hr on day 1, followed by maintenance dose of 120 mg/day; may increase frequency to q12hr for more severe infections, particularly chronic UTI

Anthrax

Anthrax due to Bacillus anthracis, including inhalational anthrax (postexposure)

≤8 years: 2.2 mg/kg PO/IV q12hr for 60 days (change to amoxicillin as soon as penicillin susceptibility confirmed)  

>8 years

• ≤45 kg: 2.2 mg/kg PO/IV q12hr for 60 days (Doryx MPC: 2.6 mg/kg PO q12hr for 60 days)
• >45 kg: 100 mg PO/IV q12hr for 60 days (Doryx MPC: 120 mg PO q12hr for 60 days)

Malaria

Prophylaxis

• Indicated for prophylaxis of malaria due to Plasmodium falciparum in short-termtravelers (<4 months) to areas with chloroquine and/or pyrimethamine-sulfadoxineresistant strains
• 2 mg/kg PO qDay; not to exceed 100 mg /day
• Doryx MPC: 2.4 mg/kg PO qDay
• Initiate treatment 1-2 days prior to travel to endemic area and continue for 4 weeks after leaving the area

Severe infection

• <45 kg: 2.2 mg/kg q12hr for 7 days with quinidine gluconate
• ≥45 kg (Off label): 100 mg PO/IV q12hr for 7 days with quinidine gluconate

Uncomplicated

• >8 years: 2.2 mg/kg; not to exceed 100 mg dose PO q12hr for 7 days with quinine sulfate

Contraindicated (6)

• acitretin

  doxycycline, acitretin. Other (see comment). Contraindicated. Comment: Both acitretin and tetracyclines can cause increased intracranial pressure.

• allogeneic cultured keratinocytes/fibroblasts in bovine collagen

  doxycycline decreases effects of allogeneic cultured keratinocytes/fibroblasts in bovine collagen by Other (see comment). Contraindicated. Comment: Exposure to topical antibiotics has been shown to degrade Gintuit; if exposed, irrigate the wound thoroughly with saline and allow a suitable wash-out period to elapse before applying Gintuit.

• flibanserin

  doxycycline will increase the level or effect of flibanserin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Coadministration of flibanserin with moderate or strong CYP3A4 inhibitors is contraindicated. Severe hypotension or syncope can occur.

• lomitapide

  doxycycline increases levels of lomitapide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Increases lomitapide levels several folds.

• lonafarnib

  doxycycline will increase the level or effect of lonafarnib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Lonafarnib is a sensitive CYP3A4 substrate. Coadministration with strong or moderate CYP3A4 inhibitors is contraindicated.

• tretinoin

  doxycycline, tretinoin. Either increases toxicity of the other by unspecified interaction mechanism. Contraindicated. Both tretinoin and tetracyclines can cause increased intracranial pressure.

Serious - Use Alternative (84)

• aluminum hydroxide

  aluminum hydroxide decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Separate by 2 hours.

• aminolevulinic acid oral

  aminolevulinic acid oral, doxycycline. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Avoid administering other phototoxic drugs with aminolevulinic acid oral for 24 hr during perioperative period.

• aminolevulinic acid topical

  doxycycline increases toxicity of aminolevulinic acid topical by pharmacodynamic synergism. Avoid or Use Alternate Drug. Coadministration of photosensitizing drugs may enhance the phototoxic reaction to photodynamic therapy with aminolevulinic acid.

• amoxicillin

  doxycycline decreases effects of amoxicillin by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Tetracyclines may interfere with the bactericidal action of penicillins. Monitor for decreased therapeutic effects of penicillins if concomitantly used with a tetracycline.

• ampicillin

  doxycycline decreases effects of ampicillin by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Tetracyclines may interfere with the bactericidal action of penicillins. Monitor for decreased therapeutic effects of penicillins if concomitantly used with a tetracycline.

• atracurium

  doxycycline increases effects of atracurium by pharmacodynamic synergism. Avoid or Use Alternate Drug. Risk of respiratory depression.

• avapritinib

  doxycycline will increase the level or effect of avapritinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of avapritinib with moderate CYP3A4 inhibitors. If unable to avoid, reduce avapritinib starting dose. See drug monograph Dosage Modifications.

• axitinib

  doxycycline increases levels of axitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with moderate CYP3A4 inhibitors, monitor closely and reduce dose if necessary .

• BCG vaccine live

  doxycycline decreases effects of BCG vaccine live by pharmacodynamic antagonism. Contraindicated. Wait until Abx Tx complete to administer live bacterial vaccine.

• bismuth subsalicylate

  bismuth subsalicylate decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• bosutinib

  doxycycline increases levels of bosutinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• calcium acetate

  calcium acetate, doxycycline. Either decreases levels of the other by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Separate by 2 hours.

• calcium carbonate

  calcium carbonate, doxycycline. Either decreases levels of the other by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Separate by 2 hours.

• calcium chloride

  calcium chloride, doxycycline. Either decreases levels of the other by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Separate by 2 hours.

• calcium citrate

  calcium citrate, doxycycline. Either decreases levels of the other by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Separate by 2 hours.

• calcium gluconate

  calcium gluconate, doxycycline. Either decreases levels of the other by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Separate by 2 hours.

• carbonyl iron

  carbonyl iron decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• cholera vaccine

  doxycycline, cholera vaccine. pharmacodynamic antagonism. Avoid or Use Alternate Drug. Avoid coadministration of cholera vaccine with systemic antibiotics since these agents may be active against the vaccine strain. Do not administer cholera vaccine to patients who have received oral or parenteral antibiotics within 14 days prior to vaccination.

• cisatracurium

  doxycycline increases effects of cisatracurium by pharmacodynamic synergism. Avoid or Use Alternate Drug. Risk of respiratory depression.

• cobimetinib

  doxycycline will increase the level or effect of cobimetinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If concurrent short term (14 days or less) use of moderate CYP3A inhibitors is unavoidable for patients who are taking cobimetinib 60 mg, reduce the cobimetinib dose to 20 mg. After discontinuation of a moderate CYP3A inhibitor, resume cobimetinib 60 mg. Use an alternative to a moderate CYP3A inhibitor in patients who are taking a reduced dose of cobimetinib (40 or 20 mg daily).

• dicloxacillin

  doxycycline decreases effects of dicloxacillin by pharmacodynamic antagonism. Avoid or Use Alternate Drug.

• elacestrant

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

• eliglustat

  doxycycline increases levels of eliglustat by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Moderate CYP3A4 inhibitors are not recommended with eliglustat poor or intermediate metabolizers; reduce eliglustat dose from 84 mg BID to 84 mg once daily in extensive metabolizers .

• entrectinib

  doxycycline will increase the level or effect of entrectinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of moderate CYP3A4 inhibitors with entrectinib, a CYP3A4 substrate. If coadministration unavoidable, reduce dose to 200 mg/day for patients aged 12 y or older with BSA >1.50m2. Resume previous entrectinib dose after discontinuing moderate CYP3A inhibitor for 3-5 elimination half-lives.

• fentanyl

  doxycycline will increase the level or effect of fentanyl by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of CYP3A4 inhibitors with fentanyl is necessary, monitor patients for respiratory depression and sedation at frequent intervals and consider fentanyl dose adjustments until stable drug effects are achieved.

• fentanyl intranasal

  doxycycline will increase the level or effect of fentanyl intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of CYP3A4 inhibitors with fentanyl is necessary, monitor patients for respiratory depression and sedation at frequent intervals and consider fentanyl dose adjustments until stable drug effects are achieved.

• fentanyl transdermal

  doxycycline will increase the level or effect of fentanyl transdermal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of CYP3A4 inhibitors with fentanyl is necessary, monitor patients for respiratory depression and sedation at frequent intervals and consider fentanyl dose adjustments until stable drug effects are achieved.

• fentanyl transmucosal

  doxycycline will increase the level or effect of fentanyl transmucosal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of CYP3A4 inhibitors with fentanyl is necessary, monitor patients for respiratory depression and sedation at frequent intervals and consider fentanyl dose adjustments until stable drug effects are achieved.

• ferric maltol

  ferric maltol will decrease the level or effect of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. If alternate not possible, separate administration by at least 4 hours

• ferrous fumarate

  ferrous fumarate decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• ferrous gluconate

  ferrous gluconate decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• ferrous sulfate

  ferrous sulfate decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• infigratinib

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

• iron dextran complex

  iron dextran complex decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• iron sucrose

  iron sucrose decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• isotretinoin

  isotretinoin, doxycycline. Mechanism: unknown. Contraindicated. Risk of pseudotumor cerebri.

• ivabradine

  doxycycline will increase the level or effect of ivabradine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of ivabradine with moderate CYP3A4 inhibitors.

• lemborexant

  doxycycline will increase the level or effect of lemborexant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of lemborexant with moderate or strong CYP3A inhibitors.

• lurbinectedin

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

• magnesium chloride

  magnesium chloride decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• magnesium citrate

  magnesium citrate decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• magnesium hydroxide

  magnesium hydroxide decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• magnesium oxide

  magnesium oxide decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• magnesium sulfate

  magnesium sulfate decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• methoxyflurane

  doxycycline, methoxyflurane. Mechanism: pharmacodynamic synergism. Avoid or Use Alternate Drug. Risk of nephrotoxicity.

• methyl aminolevulinate

  doxycycline, methyl aminolevulinate. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Each drug may increase the photosensitizing effect of the other.

• microbiota oral

  doxycycline decreases effects of microbiota oral by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Microbiota oral contains bacterial spores. Antibacterial agents may decrease efficacy if coadministered. Complete antibiotic regimens 2-4 days before initiating microbiota oral. .

• midazolam intranasal

  doxycycline will increase the level or effect of midazolam intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of moderate CYP3A4 inhibitors with midazolam intranasal causes higher midazolam systemic exposure, which may prolong sedation.

• mobocertinib

  doxycycline will increase the level or effect of mobocertinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If use of moderate CYP3A4 inhibitor unavoidable, reduce mobocertinib dose by ~50% (eg, 160 to 80 mg); closely monitor QTc interval.

• nafcillin

  doxycycline decreases effects of nafcillin by pharmacodynamic antagonism. Avoid or Use Alternate Drug. bacteriostatic antibiotics may interfere with the bactericidal actions of penicillins.

• naloxegol

  doxycycline will increase the level or effect of naloxegol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministation of naloxegol with moderate CYP3A4 inhibitors is unavoidable, reduce naloxegol dose to 12.5 mg qDay

• neratinib

  doxycycline will increase the level or effect of neratinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of neratinib with strong/moderate CYP3A4 inhibitors.

• olaparib

  doxycycline will increase the level or effect of olaparib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration with moderate CYP3A inhibitors cannot be avoided, reduce olaparib dose to 200 mg (capsule) or 150 mg (tablet) PO BID. Do not substitute tablets with capsules.

• omaveloxolone

  doxycycline will increase the level or effect of omaveloxolone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unavoidable, reduce omaveloxolone dose to 100 mg/day. Closely monitor for adverse effects. If adverse effects emerge, further reduce to 50 mg/day.

• onabotulinumtoxinA

  doxycycline increases effects of onabotulinumtoxinA by pharmacodynamic synergism. Avoid or Use Alternate Drug. Risk of respiratory depression.

• oxacillin

  doxycycline decreases effects of oxacillin by pharmacodynamic antagonism. Avoid or Use Alternate Drug. bacteriostatic agents may inhibit the effects of bactericidal agents.

• pacritinib

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

• pancuronium

  doxycycline increases effects of pancuronium by pharmacodynamic synergism. Avoid or Use Alternate Drug. Risk of respiratory depression.

• pemigatinib

  doxycycline will increase the level or effect of pemigatinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration with strong or moderate CYP3A4 inhibitors is unavoidable, reduce pemigatinib dose (refer to drug monograph dosage modifications). After discontinuing the CYP3A4 inhibitor for 3 elimination half-lives, may resume previous pemigatinib dose.

• penicillin G aqueous

  doxycycline decreases effects of penicillin G aqueous by pharmacodynamic antagonism. Avoid or Use Alternate Drug.

• penicillin VK

  doxycycline decreases effects of penicillin VK by pharmacodynamic antagonism. Avoid or Use Alternate Drug.

• pexidartinib

  doxycycline will increase the level or effect of pexidartinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration with strong or moderate CYP3A4 inhibitors is unavoidable, reduce pexidartinib dose (refer to drug monograph dosage modifications). After discontinuing the CYP3A4 inhibitor for 3 elimination half-lives, may resume previous pexidartinib dose.

• pivmecillinam

  doxycycline decreases effects of pivmecillinam by pharmacodynamic antagonism. Avoid or Use Alternate Drug.

• polysaccharide iron

  polysaccharide iron decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• rapacuronium

  doxycycline increases effects of rapacuronium by pharmacodynamic synergism. Avoid or Use Alternate Drug. Risk of respiratory depression.

• rocuronium

  doxycycline increases effects of rocuronium by pharmacodynamic synergism. Avoid or Use Alternate Drug. Risk of respiratory depression.

• rose hips

  rose hips decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• selumetinib

  doxycycline will increase the level or effect of selumetinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration with strong or moderate CYP3A4 inhibitors cannot be avoided, reduce selumetinib dosage (refer to selumetinib monograph for further information). After discontinuation of the strong or moderate CYP3A4 inhibitor for 3 elimination half-lives, resume selumetinib dose that was taken before initiating the inhibitor.

• siponimod

  doxycycline will increase the level or effect of siponimod by affecting hepatic enzyme CYP2E1 metabolism. Avoid or Use Alternate Drug. Coadministration of siponimod with a moderate or strong CYP3A4 inhibitor PLUS a moderate or strong CYP2C9 inhibitor is not recommended.

• sodium bicarbonate

  sodium bicarbonate decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Separate by 2 hours.

• sodium citrate/citric acid

  sodium citrate/citric acid decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Separate by 2 hours.

• sodium sulfate/?magnesium sulfate/potassium chloride

  sodium sulfate/?magnesium sulfate/potassium chloride decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Administer tetracyclines at least 2 hr before and no less than 6 hr after each dose to avoid chelation with magnesium. .

• sodium sulfate/potassium sulfate/magnesium sulfate

  sodium sulfate/potassium sulfate/magnesium sulfate decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Administer tetracyclines at least 2 hr before and no less than 6 hr after each dose to avoid chelation with magnesium. .

• strontium ranelate

  strontium ranelate decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Contraindicated. Suspend strontium ranelate during antibiotic therapy.

• succinylcholine

  doxycycline increases effects of succinylcholine by pharmacodynamic synergism. Avoid or Use Alternate Drug. Risk of respiratory depression.

• tazemetostat

  doxycycline will increase the level or effect of tazemetostat by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of tazemetostat with moderate CYP3A4 inhibitors. If coadministration is unavoidable, reduce tazemetostat current dose (see drug monograph Dosage Modifications).

• temocillin

  doxycycline decreases effects of temocillin by pharmacodynamic antagonism. Avoid or Use Alternate Drug.

• ticarcillin

  doxycycline decreases effects of ticarcillin by pharmacodynamic antagonism. Avoid or Use Alternate Drug.

• tretinoin

  doxycycline, tretinoin. Either increases levels of the other by Mechanism: pharmacodynamic synergism. Avoid or Use Alternate Drug. Increased phototoxicity.

• tretinoin topical

  doxycycline, tretinoin topical. Mechanism: pharmacodynamic synergism. Avoid or Use Alternate Drug. Increased phototoxicity.

• tripotassium dicitratobismuthate

  tripotassium dicitratobismuthate decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• typhoid vaccine live

  doxycycline decreases effects of typhoid vaccine live by pharmacodynamic antagonism. Contraindicated. Wait until Abx Tx complete to administer live bacterial vaccine.

• vecuronium

  doxycycline increases effects of vecuronium by pharmacodynamic synergism. Avoid or Use Alternate Drug. Risk of respiratory depression.

• venetoclax

  doxycycline will increase the level or effect of venetoclax by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If a moderate CYP3A inhibitor must be used, reduce the venetoclax dose by at least 50%. Monitor more closely for signs of venetoclax toxicities.

Monitor Closely (78)

• acalabrutinib

  doxycycline will increase the level or effect of acalabrutinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Decrease acalabrutinib dose to 100 mg once daily if coadministered with a moderate CYP3A inhibitor.

• amobarbital

  amobarbital decreases levels of doxycycline by increasing metabolism. Use Caution/Monitor.

• atogepant

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

• bazedoxifene/conjugated estrogens

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

• brexpiprazole

  doxycycline will increase the level or effect of brexpiprazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Administer a quarter of brexpiprazole dose if coadministered with a moderate CYP3A4 inhibitor PLUS a strong/moderate CYP2D6 inhibitor.

• buprenorphine subdermal implant

  doxycycline will increase the level or effect of buprenorphine subdermal implant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Monitor patients already on buprenorphine subdermal implant who require newly-initiated treatment with CYP3A4 inhibitors for signs and symptoms of overmedication. If the dose of the concomitant CYP3A4 inhibitor cannot be reduced or discontinued, implant removal may be necessary and the patient should then be treated with a buprenorphine dosage form that permits dose adjustments. If a CYP3A4 inhibitor is discontinued in a patient who has been stabilized on buprenorphine, monitor the patient for withdrawal.

• buprenorphine, long-acting injection

  doxycycline will increase the level or effect of buprenorphine, long-acting injection by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Patients who transfer to buprenorphine long-acting injection from transmucosal buprenorphine coadministered with CYP3A4 inhibitors should be monitored to ensure buprenorphine plasma levels are adequate. Within 2 weeks, if signs and symptoms of buprenorphine toxicity or overdose occur and the concomitant CYP3A4 inhibitor cannot be reduced or discontinued, transition the patient back to a buprenorphine formulation that permits dose adjustments.

• butabarbital

  butabarbital decreases levels of doxycycline by increasing metabolism. Use Caution/Monitor.

• butalbital

  butalbital decreases levels of doxycycline by increasing metabolism. Use Caution/Monitor.

• cabozantinib

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

• cannabidiol

  doxycycline will increase the level or effect of cannabidiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Consider reducing the cannabidiol dose when coadministered with a moderate CYP3A4 inhibitor.

• carbamazepine

  carbamazepine decreases levels of doxycycline by increasing metabolism. Use Caution/Monitor.

• cefdinir

  doxycycline decreases effects of cefdinir by pharmacodynamic antagonism. Use Caution/Monitor. bacteriostatic agents may inhibit the effects of bactericidal agents.

• cefditoren

  doxycycline decreases effects of cefditoren by pharmacodynamic antagonism. Use Caution/Monitor. bacteriostatic agents may inhibit the effects of bactericidal agents.

• cefoxitin

  doxycycline decreases effects of cefoxitin by pharmacodynamic antagonism. Use Caution/Monitor. bacteriostatic agents may inhibit the effects of bactericidal agents.

• cefpodoxime

  doxycycline decreases effects of cefpodoxime by pharmacodynamic antagonism. Use Caution/Monitor. bacteriostatic agents may inhibit the effects of bactericidal agents.

• ceftriaxone

  doxycycline decreases effects of ceftriaxone by pharmacodynamic antagonism. Use Caution/Monitor. bacteriostatic agents may inhibit the effects of bactericidal agents.

• cefuroxime

  doxycycline decreases effects of cefuroxime by pharmacodynamic antagonism. Use Caution/Monitor. bacteriostatic agents may inhibit the effects of bactericidal agents.

• cholestyramine

  cholestyramine decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.

• conjugated estrogens

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

• daridorexant

  doxycycline will increase the level or effect of daridorexant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Daridorexant dose should not exceed 25 mg per night when coadministered with moderate CYP3A4 inhibitors.

• deflazacort

  doxycycline will increase the level or effect of deflazacort by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Decrease deflazacort dose to one-third of the recommended dose if coadministered with moderate or strong CYP3A4 inhibitors.

• didanosine

  didanosine will decrease the level or effect of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Applies to didanosine chewable tablets and powder for oral solution; administer 2 hr before or several hours after didanosine oral solution or chewable tablet administration

• digoxin

  doxycycline will increase the level or effect of digoxin by altering intestinal flora. Applies only to oral form of both agents. Use Caution/Monitor.

• estradiol

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

• estrogens conjugated synthetic

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

• estropipate

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

• ethinylestradiol

  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.

• ferric citrate

  ferric citrate will decrease the level or effect of doxycycline by drug binding in GI tract. Use Caution/Monitor. Administer doxycycline at least 1 hr before ferric citrate

• finerenone

  doxycycline 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 moderate CYP3A4 inhibitors. Adjust finererone dosage as needed.

• guanfacine

  doxycycline will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.

• ibrutinib

  doxycycline increases levels of ibrutinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration with moderate CYP3A4 inhibitors, reduce ibrutinib dose to 280 mg qDay (B-cell malignancies) or 420 mg qDay (graft versus host disease). After CYP3A inhibitor discontinuation, resume previous dose of ibrutinib.

• ifosfamide

  doxycycline will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• isavuconazonium sulfate

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

• ivosidenib

  doxycycline will increase the level or effect of ivosidenib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration with moderate CYP3A4 inhibitors may increase ivosidenib plasma concentrations, thus increasing the risk of QTc prolongation. Monitor for increased risk of QTc interval prolongation.

• lanthanum carbonate

  lanthanum carbonate decreases levels of doxycycline by cation binding in GI tract. Use Caution/Monitor. Administer oral tetracycline antibiotics at least 2 hr before or after lanthanum. Interaction applies only to oral tetracyclines.

• lefamulin

  doxycycline will increase the level or effect of lefamulin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor for adverse effects if lefamulin is coadministered with moderate CYP3A inhibitors.

• levamlodipine

  doxycycline will increase the level or effect of levamlodipine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration with moderate and strong CYP3A inhibitors results in increased systemic exposure to amlodipine and may require dose reduction. Monitor for symptoms of hypotension and edema when amlodipine is coadministered with CYP3A inhibitors to determine the need for dose adjustment.

• levonorgestrel oral/ethinylestradiol/ferrous bisglycinate

  doxycycline will decrease the level or effect of levonorgestrel oral/ethinylestradiol/ferrous bisglycinate 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.

• lumateperone

  doxycycline will increase the level or effect of lumateperone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce lumateperone dose to 21 mg/day if coadministered with moderate CYP3A4 inhibitors.

• magnesium supplement

  magnesium supplement will decrease the level or effect of doxycycline by Other (see comment). Modify Therapy/Monitor Closely. Formation of an insoluble complex reduces absorption of the drug through intestinal tract; administer magnesium 2hr before the tetracycline or 4hr after the tetracycline.

• mavacamten

  doxycycline will increase the level or effect of mavacamten by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Inititiation of moderate CYP3A4 inhibitors may require decreased mavacamten dose.

• mefloquine

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

• mestranol

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

• methotrexate

  doxycycline increases levels of methotrexate by decreasing elimination. Use Caution/Monitor. Tetracyclines may decrease intestinal absorption of methotrexate or interfere with the enterohepatic circulation by inhibiting bowel flora and suppressing metabolism of the drug by bacteria.

• methoxsalen

  methoxsalen, doxycycline. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive photosensitizing effects.

• mipomersen

  mipomersen, doxycycline. Either increases toxicity of the other by Other (see comment). Use Caution/Monitor. Comment: Both drugs have potential to increase hepatic enzymes; monitor LFTs.

• naldemedine

  doxycycline increases levels of naldemedine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor naldemedine for potential adverse effects if coadministered with strong or moderate CYP3A4 inhibitors.

• oliceridine

  doxycycline will increase the level or effect of oliceridine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. If concomitant use is necessary, may require less frequent oliceridine dosing. Closely monitor for respiratory depression and sedation and titrate subsequent doses accordingly. If inhibitor is discontinued, consider increase oliceridine dosage until stable drug effects are achieved. Monitor for signs of opioid withdrawal.

• ospemifene

  doxycycline, ospemifene. Either increases levels of the other by plasma protein binding competition. Modify Therapy/Monitor Closely.

• palbociclib

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

• pentobarbital

  pentobarbital decreases levels of doxycycline by increasing metabolism. Use Caution/Monitor.

• phenobarbital

  phenobarbital decreases levels of doxycycline by increasing metabolism. Use Caution/Monitor.

• piperacillin

  doxycycline decreases effects of piperacillin by pharmacodynamic antagonism. Use Caution/Monitor. bacteriostatic agents may inhibit the effects of bactericidal agents.

• polycarbophil

  polycarbophil decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.

• porfimer

  doxycycline, porfimer. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Enhanced photosensitivity.

• primidone

  primidone decreases levels of doxycycline by increasing metabolism. Use Caution/Monitor.

• rimegepant

  doxycycline will increase the level or effect of rimegepant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Avoid repeating rimegepant dose within 48 hr if coadministered with a moderate CYP3A4 inhibitor.

• ruxolitinib

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

• ruxolitinib topical

  doxycycline will increase the level or effect of ruxolitinib topical by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor.

• secobarbital

  secobarbital decreases levels of doxycycline by increasing metabolism. Use Caution/Monitor.

• sodium picosulfate/magnesium oxide/anhydrous citric acid

  doxycycline decreases effects of sodium picosulfate/magnesium oxide/anhydrous citric acid by altering metabolism. Use Caution/Monitor. Coadministration with antibiotics decreases efficacy by altering colonic bacterial flora needed to convert sodium picosulfate to active drug.
  
  sodium picosulfate/magnesium oxide/anhydrous citric acid decreases levels of doxycycline by cation binding in GI tract. Use Caution/Monitor. Take at least 2 hours before and not less than 6 hours after administration of sodium picosulfate, magnesium oxide and anhydrous citric acid to avoid magnesium chelation.

• sonidegib

  doxycycline will increase the level or effect of sonidegib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Avoid coadministration of sonidegib with moderate CYP3A4 inhibitors. If a moderate CYP3A inhibitor must be used, administer the moderate CYP3A inhibitor for <14 days and monitor closely for adverse reactions, particularly musculoskeletal adverse reactions.

• sparsentan

  doxycycline will increase the level or effect of sparsentan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. No dosage adjustment needed. Monitor blood pressure, serum potassium, edema, and kidney function regularly if sparsentan is coadministered with moderate CYP3A4 inhibitors.

• sucroferric oxyhydroxide

  sucroferric oxyhydroxide decreases levels of doxycycline by drug binding in GI tract. Use Caution/Monitor. Do not administer at the same time; take doxycycline at least 1 hr before sucroferric oxyhydroxide.

• sufentanil SL

  doxycycline will increase the level or effect of sufentanil SL by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of sufentanil SL with any CYP3A4 inhibitor may increase sufentanil plasma concentration, and, thereby increase or prolonged adverse effects, including potentially fatal respiratory depression.

• suvorexant

  doxycycline will increase the level or effect of suvorexant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Decrease suvorexant starting dose to 5 mg HS if coadministered with moderate CYP3A4 inhibitors

• tamsulosin

  doxycycline increases levels of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Dose reduction may be needed for coadministered drugs that are predominantly metabolized by CYP3A.

• tezacaftor

  doxycycline will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.

• tinidazole

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

• tofacitinib

  doxycycline increases levels of tofacitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. No specific dose adjustment recommended when tofacitinib coadministered with moderate CYP3A4 inhibitors; decrease tofacitinib dose if coadministered with both moderate CYP3A4 and potent CYP2C19 inhibitors.

• trabectedin

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

• trimagnesium citrate anhydrous

  trimagnesium citrate anhydrous decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Multivalent cation-containing products may reduce bioavailability of tetracyclines; administer tetracycline at least 2 hr before or 6 hr after magnesium; use alternatives if available.

• vardenafil

  doxycycline will increase the level or effect of vardenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Vardenafil dose may need to be reduced if coadministered with moderate or strong CYP3A4 inhibitors

• voclosporin

  doxycycline will increase the level or effect of voclosporin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce voclosporin daily dosage to 15.8 mg PO in AM and 7.9 mg PO in PM.

• warfarin

  doxycycline increases effects of warfarin by unspecified interaction mechanism. Use Caution/Monitor.

• zanubrutinib

  doxycycline will increase the level or effect of zanubrutinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce zanubrutinib (a CYP3A4 substrate) to 80 mg PO BID to when coadministered with a moderate CYP3A4 inhibitor. Interrupt dose as recommended for adverse reactions. After discontinuing the CYP3A4 inhibitor, resume previous dose of zanubrutinib.

• zinc

  zinc will decrease the level or effect of doxycycline by cation binding in GI tract. Modify Therapy/Monitor Closely. Separate administration of oral tetracycline derivatives and oral zinc salts by at least 2 hr.

Minor (30)

• antithrombin alfa

  doxycycline increases effects of antithrombin alfa by pharmacodynamic synergism. Minor/Significance Unknown.

• antithrombin III

  doxycycline increases effects of antithrombin III by pharmacodynamic synergism. Minor/Significance Unknown.

• argatroban

  doxycycline increases effects of argatroban by pharmacodynamic synergism. Minor/Significance Unknown.

• balsalazide

  doxycycline will decrease the level or effect of balsalazide by altering intestinal flora. Applies only to oral form of both agents. Minor/Significance Unknown.

• bemiparin

  doxycycline increases effects of bemiparin by pharmacodynamic synergism. Minor/Significance Unknown.

• biotin

  doxycycline will decrease the level or effect of biotin by altering intestinal flora. Applies only to oral form of both agents. Minor/Significance Unknown.

• bivalirudin

  doxycycline increases effects of bivalirudin by pharmacodynamic synergism. Minor/Significance Unknown.

• colestipol

  colestipol decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Minor/Significance Unknown.

• dalteparin

  doxycycline increases effects of dalteparin by pharmacodynamic synergism. Minor/Significance Unknown.

• enoxaparin

  doxycycline increases effects of enoxaparin by pharmacodynamic synergism. Minor/Significance Unknown.

• eslicarbazepine acetate

  eslicarbazepine acetate decreases levels of doxycycline by increasing metabolism. Minor/Significance Unknown.

• estradiol vaginal

  doxycycline will increase the level or effect of estradiol vaginal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Minor/Significance Unknown.

• ethanol

  ethanol decreases levels of doxycycline by increasing elimination. Minor/Significance Unknown.

• ethotoin

  ethotoin decreases levels of doxycycline by increasing metabolism. Minor/Significance Unknown.

• fondaparinux

  doxycycline increases effects of fondaparinux by pharmacodynamic synergism. Minor/Significance Unknown.

• fosphenytoin

  fosphenytoin decreases levels of doxycycline by increasing metabolism. Minor/Significance Unknown.

• heparin

  doxycycline increases effects of heparin by pharmacodynamic synergism. Minor/Significance Unknown.

• niacin

  doxycycline will decrease the level or effect of niacin by altering intestinal flora. Applies only to oral form of both agents. Minor/Significance Unknown.

• oxcarbazepine

  oxcarbazepine decreases levels of doxycycline by increasing metabolism. Minor/Significance Unknown.

• pantothenic acid

  doxycycline will decrease the level or effect of pantothenic acid by altering intestinal flora. Applies only to oral form of both agents. Minor/Significance Unknown.

• phenindione

  doxycycline increases effects of phenindione by pharmacodynamic synergism. Minor/Significance Unknown.

• phenytoin

  phenytoin decreases levels of doxycycline by increasing metabolism. Minor/Significance Unknown.

• protamine

  doxycycline increases effects of protamine by pharmacodynamic synergism. Minor/Significance Unknown.

• pyridoxine

  doxycycline will decrease the level or effect of pyridoxine by altering intestinal flora. Applies only to oral form of both agents. Minor/Significance Unknown.

• pyridoxine (Antidote)

  doxycycline will decrease the level or effect of pyridoxine (Antidote) by altering intestinal flora. Applies only to oral form of both agents. Minor/Significance Unknown.

• rifabutin

  rifabutin decreases levels of doxycycline by increasing metabolism. Minor/Significance Unknown.

• rose hips

  doxycycline decreases levels of rose hips by increasing elimination. Minor/Significance Unknown.

• sucralfate

  sucralfate decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Minor/Significance Unknown.

• thiamine

  doxycycline will decrease the level or effect of thiamine by altering intestinal flora. Applies only to oral form of both agents. Minor/Significance Unknown.

• verteporfin

  doxycycline, verteporfin. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Increased phototoxicity.

• acalabrutinib

  Monitor Closely (1)doxycycline will increase the level or effect of acalabrutinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Decrease acalabrutinib dose to 100 mg once daily if coadministered with a moderate CYP3A inhibitor.

• acitretin

  Contraindicated (1)doxycycline, acitretin. Other (see comment). Contraindicated. Comment: Both acitretin and tetracyclines can cause increased intracranial pressure.

• allogeneic cultured keratinocytes/fibroblasts in bovine collagen

  Contraindicated (1)doxycycline decreases effects of allogeneic cultured keratinocytes/fibroblasts in bovine collagen by Other (see comment). Contraindicated. Comment: Exposure to topical antibiotics has been shown to degrade Gintuit; if exposed, irrigate the wound thoroughly with saline and allow a suitable wash-out period to elapse before applying Gintuit.

• aluminum hydroxide

  Serious - Use Alternative (1)aluminum hydroxide decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Separate by 2 hours.

• aminolevulinic acid oral

  Serious - Use Alternative (1)aminolevulinic acid oral, doxycycline. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Avoid administering other phototoxic drugs with aminolevulinic acid oral for 24 hr during perioperative period.

• aminolevulinic acid topical

  Serious - Use Alternative (1)doxycycline increases toxicity of aminolevulinic acid topical by pharmacodynamic synergism. Avoid or Use Alternate Drug. Coadministration of photosensitizing drugs may enhance the phototoxic reaction to photodynamic therapy with aminolevulinic acid.

• amobarbital

  Monitor Closely (1)amobarbital decreases levels of doxycycline by increasing metabolism. Use Caution/Monitor.

• amoxicillin

  Serious - Use Alternative (1)doxycycline decreases effects of amoxicillin by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Tetracyclines may interfere with the bactericidal action of penicillins. Monitor for decreased therapeutic effects of penicillins if concomitantly used with a tetracycline.

• ampicillin

  Serious - Use Alternative (1)doxycycline decreases effects of ampicillin by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Tetracyclines may interfere with the bactericidal action of penicillins. Monitor for decreased therapeutic effects of penicillins if concomitantly used with a tetracycline.

• antithrombin alfa

  Minor (1)doxycycline increases effects of antithrombin alfa by pharmacodynamic synergism. Minor/Significance Unknown.

• antithrombin III

  Minor (1)doxycycline increases effects of antithrombin III by pharmacodynamic synergism. Minor/Significance Unknown.

• argatroban

  Minor (1)doxycycline increases effects of argatroban by pharmacodynamic synergism. Minor/Significance Unknown.

• atogepant

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

• atracurium

  Serious - Use Alternative (1)doxycycline increases effects of atracurium by pharmacodynamic synergism. Avoid or Use Alternate Drug. Risk of respiratory depression.

• avapritinib

  Serious - Use Alternative (1)doxycycline will increase the level or effect of avapritinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of avapritinib with moderate CYP3A4 inhibitors. If unable to avoid, reduce avapritinib starting dose. See drug monograph Dosage Modifications.

• axitinib

  Serious - Use Alternative (1)doxycycline increases levels of axitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unable to avoid coadministration with moderate CYP3A4 inhibitors, monitor closely and reduce dose if necessary .

• balsalazide

  Minor (1)doxycycline will decrease the level or effect of balsalazide by altering intestinal flora. Applies only to oral form of both agents. Minor/Significance Unknown.

• bazedoxifene/conjugated estrogens

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

• BCG vaccine live

  Serious - Use Alternative (1)doxycycline decreases effects of BCG vaccine live by pharmacodynamic antagonism. Contraindicated. Wait until Abx Tx complete to administer live bacterial vaccine.

• bemiparin

  Minor (1)doxycycline increases effects of bemiparin by pharmacodynamic synergism. Minor/Significance Unknown.

• biotin

  Minor (1)doxycycline will decrease the level or effect of biotin by altering intestinal flora. Applies only to oral form of both agents. Minor/Significance Unknown.

• bismuth subsalicylate

  Serious - Use Alternative (1)bismuth subsalicylate decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• bivalirudin

  Minor (1)doxycycline increases effects of bivalirudin by pharmacodynamic synergism. Minor/Significance Unknown.

• bosutinib

  Serious - Use Alternative (1)doxycycline increases levels of bosutinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug.

• brexpiprazole

  Monitor Closely (1)doxycycline will increase the level or effect of brexpiprazole by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Administer a quarter of brexpiprazole dose if coadministered with a moderate CYP3A4 inhibitor PLUS a strong/moderate CYP2D6 inhibitor.

• buprenorphine subdermal implant

  Monitor Closely (1)doxycycline will increase the level or effect of buprenorphine subdermal implant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Monitor patients already on buprenorphine subdermal implant who require newly-initiated treatment with CYP3A4 inhibitors for signs and symptoms of overmedication. If the dose of the concomitant CYP3A4 inhibitor cannot be reduced or discontinued, implant removal may be necessary and the patient should then be treated with a buprenorphine dosage form that permits dose adjustments. If a CYP3A4 inhibitor is discontinued in a patient who has been stabilized on buprenorphine, monitor the patient for withdrawal.

• buprenorphine, long-acting injection

  Monitor Closely (1)doxycycline will increase the level or effect of buprenorphine, long-acting injection by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Patients who transfer to buprenorphine long-acting injection from transmucosal buprenorphine coadministered with CYP3A4 inhibitors should be monitored to ensure buprenorphine plasma levels are adequate. Within 2 weeks, if signs and symptoms of buprenorphine toxicity or overdose occur and the concomitant CYP3A4 inhibitor cannot be reduced or discontinued, transition the patient back to a buprenorphine formulation that permits dose adjustments.

• butabarbital

  Monitor Closely (1)butabarbital decreases levels of doxycycline by increasing metabolism. Use Caution/Monitor.

• butalbital

  Monitor Closely (1)butalbital decreases levels of doxycycline by increasing metabolism. Use Caution/Monitor.

• cabozantinib

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

• calcium acetate

  Serious - Use Alternative (1)calcium acetate, doxycycline. Either decreases levels of the other by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Separate by 2 hours.

• calcium carbonate

  Serious - Use Alternative (1)calcium carbonate, doxycycline. Either decreases levels of the other by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Separate by 2 hours.

• calcium chloride

  Serious - Use Alternative (1)calcium chloride, doxycycline. Either decreases levels of the other by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Separate by 2 hours.

• calcium citrate

  Serious - Use Alternative (1)calcium citrate, doxycycline. Either decreases levels of the other by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Separate by 2 hours.

• calcium gluconate

  Serious - Use Alternative (1)calcium gluconate, doxycycline. Either decreases levels of the other by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Separate by 2 hours.

• cannabidiol

  Monitor Closely (1)doxycycline will increase the level or effect of cannabidiol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Consider reducing the cannabidiol dose when coadministered with a moderate CYP3A4 inhibitor.

• carbamazepine

  Monitor Closely (1)carbamazepine decreases levels of doxycycline by increasing metabolism. Use Caution/Monitor.

• carbonyl iron

  Serious - Use Alternative (1)carbonyl iron decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• cefdinir

  Monitor Closely (1)doxycycline decreases effects of cefdinir by pharmacodynamic antagonism. Use Caution/Monitor. bacteriostatic agents may inhibit the effects of bactericidal agents.

• cefditoren

  Monitor Closely (1)doxycycline decreases effects of cefditoren by pharmacodynamic antagonism. Use Caution/Monitor. bacteriostatic agents may inhibit the effects of bactericidal agents.

• cefoxitin

  Monitor Closely (1)doxycycline decreases effects of cefoxitin by pharmacodynamic antagonism. Use Caution/Monitor. bacteriostatic agents may inhibit the effects of bactericidal agents.

• cefpodoxime

  Monitor Closely (1)doxycycline decreases effects of cefpodoxime by pharmacodynamic antagonism. Use Caution/Monitor. bacteriostatic agents may inhibit the effects of bactericidal agents.

• ceftriaxone

  Monitor Closely (1)doxycycline decreases effects of ceftriaxone by pharmacodynamic antagonism. Use Caution/Monitor. bacteriostatic agents may inhibit the effects of bactericidal agents.

• cefuroxime

  Monitor Closely (1)doxycycline decreases effects of cefuroxime by pharmacodynamic antagonism. Use Caution/Monitor. bacteriostatic agents may inhibit the effects of bactericidal agents.

• cholera vaccine

  Serious - Use Alternative (1)doxycycline, cholera vaccine. pharmacodynamic antagonism. Avoid or Use Alternate Drug. Avoid coadministration of cholera vaccine with systemic antibiotics since these agents may be active against the vaccine strain. Do not administer cholera vaccine to patients who have received oral or parenteral antibiotics within 14 days prior to vaccination.

• cholestyramine

  Monitor Closely (1)cholestyramine decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.

• cisatracurium

  Serious - Use Alternative (1)doxycycline increases effects of cisatracurium by pharmacodynamic synergism. Avoid or Use Alternate Drug. Risk of respiratory depression.

• cobimetinib

  Serious - Use Alternative (1)doxycycline will increase the level or effect of cobimetinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If concurrent short term (14 days or less) use of moderate CYP3A inhibitors is unavoidable for patients who are taking cobimetinib 60 mg, reduce the cobimetinib dose to 20 mg. After discontinuation of a moderate CYP3A inhibitor, resume cobimetinib 60 mg. Use an alternative to a moderate CYP3A inhibitor in patients who are taking a reduced dose of cobimetinib (40 or 20 mg daily).

• colestipol

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

• conjugated estrogens

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

• dalteparin

  Minor (1)doxycycline increases effects of dalteparin by pharmacodynamic synergism. Minor/Significance Unknown.

• daridorexant

  Monitor Closely (1)doxycycline will increase the level or effect of daridorexant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Daridorexant dose should not exceed 25 mg per night when coadministered with moderate CYP3A4 inhibitors.

• deflazacort

  Monitor Closely (1)doxycycline will increase the level or effect of deflazacort by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Decrease deflazacort dose to one-third of the recommended dose if coadministered with moderate or strong CYP3A4 inhibitors.

• dicloxacillin

  Serious - Use Alternative (1)doxycycline decreases effects of dicloxacillin by pharmacodynamic antagonism. Avoid or Use Alternate Drug.

• didanosine

  Monitor Closely (1)didanosine will decrease the level or effect of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Applies to didanosine chewable tablets and powder for oral solution; administer 2 hr before or several hours after didanosine oral solution or chewable tablet administration

• digoxin

  Monitor Closely (1)doxycycline will increase the level or effect of digoxin by altering intestinal flora. Applies only to oral form of both agents. Use Caution/Monitor.

• elacestrant

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

• eliglustat

  Serious - Use Alternative (1)doxycycline increases levels of eliglustat by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Moderate CYP3A4 inhibitors are not recommended with eliglustat poor or intermediate metabolizers; reduce eliglustat dose from 84 mg BID to 84 mg once daily in extensive metabolizers .

• enoxaparin

  Minor (1)doxycycline increases effects of enoxaparin by pharmacodynamic synergism. Minor/Significance Unknown.

• entrectinib

  Serious - Use Alternative (1)doxycycline will increase the level or effect of entrectinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of moderate CYP3A4 inhibitors with entrectinib, a CYP3A4 substrate. If coadministration unavoidable, reduce dose to 200 mg/day for patients aged 12 y or older with BSA >1.50m2. Resume previous entrectinib dose after discontinuing moderate CYP3A inhibitor for 3-5 elimination half-lives.

• eslicarbazepine acetate

  Minor (1)eslicarbazepine acetate decreases levels of doxycycline by increasing metabolism. Minor/Significance Unknown.

• estradiol

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

• estradiol vaginal

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

• estrogens conjugated synthetic

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

• estropipate

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

• ethanol

  Minor (1)ethanol decreases levels of doxycycline by increasing elimination. Minor/Significance Unknown.

• ethinylestradiol

  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.

• ethotoin

  Minor (1)ethotoin decreases levels of doxycycline by increasing metabolism. Minor/Significance Unknown.

• fentanyl

  Serious - Use Alternative (1)doxycycline will increase the level or effect of fentanyl by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of CYP3A4 inhibitors with fentanyl is necessary, monitor patients for respiratory depression and sedation at frequent intervals and consider fentanyl dose adjustments until stable drug effects are achieved.

• fentanyl intranasal

  Serious - Use Alternative (1)doxycycline will increase the level or effect of fentanyl intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of CYP3A4 inhibitors with fentanyl is necessary, monitor patients for respiratory depression and sedation at frequent intervals and consider fentanyl dose adjustments until stable drug effects are achieved.

• fentanyl transdermal

  Serious - Use Alternative (1)doxycycline will increase the level or effect of fentanyl transdermal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of CYP3A4 inhibitors with fentanyl is necessary, monitor patients for respiratory depression and sedation at frequent intervals and consider fentanyl dose adjustments until stable drug effects are achieved.

• fentanyl transmucosal

  Serious - Use Alternative (1)doxycycline will increase the level or effect of fentanyl transmucosal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration of CYP3A4 inhibitors with fentanyl is necessary, monitor patients for respiratory depression and sedation at frequent intervals and consider fentanyl dose adjustments until stable drug effects are achieved.

• ferric citrate

  Monitor Closely (1)ferric citrate will decrease the level or effect of doxycycline by drug binding in GI tract. Use Caution/Monitor. Administer doxycycline at least 1 hr before ferric citrate

• ferric maltol

  Serious - Use Alternative (1)ferric maltol will decrease the level or effect of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. If alternate not possible, separate administration by at least 4 hours

• ferrous fumarate

  Serious - Use Alternative (1)ferrous fumarate decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• ferrous gluconate

  Serious - Use Alternative (1)ferrous gluconate decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• ferrous sulfate

  Serious - Use Alternative (1)ferrous sulfate decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• finerenone

  Monitor Closely (1)doxycycline 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 moderate CYP3A4 inhibitors. Adjust finererone dosage as needed.

• flibanserin

  Contraindicated (1)doxycycline will increase the level or effect of flibanserin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Coadministration of flibanserin with moderate or strong CYP3A4 inhibitors is contraindicated. Severe hypotension or syncope can occur.

• fondaparinux

  Minor (1)doxycycline increases effects of fondaparinux by pharmacodynamic synergism. Minor/Significance Unknown.

• fosphenytoin

  Minor (1)fosphenytoin decreases levels of doxycycline by increasing metabolism. Minor/Significance Unknown.

• guanfacine

  Monitor Closely (1)doxycycline will increase the level or effect of guanfacine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Strong or moderate CYP3A4 inhibitors significantly increase guanfacine plasma concentrations. FDA-approved labeling for extended-release (ER) guanfacine recommends that, if coadministered, the guanfacine dosage should be decreased to half of the recommended dose. Specific recommendations for immediate-release (IR) guanfacine are not available.

• heparin

  Minor (1)doxycycline increases effects of heparin by pharmacodynamic synergism. Minor/Significance Unknown.

• ibrutinib

  Monitor Closely (1)doxycycline increases levels of ibrutinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration with moderate CYP3A4 inhibitors, reduce ibrutinib dose to 280 mg qDay (B-cell malignancies) or 420 mg qDay (graft versus host disease). After CYP3A inhibitor discontinuation, resume previous dose of ibrutinib.

• ifosfamide

  Monitor Closely (1)doxycycline will decrease the level or effect of ifosfamide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Use of a CYP3A4 inhibitor may decrease metabolism of ifosfamide, potentially reducing ifosfamide therapeutic effects.

• infigratinib

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

• iron dextran complex

  Serious - Use Alternative (1)iron dextran complex decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• iron sucrose

  Serious - Use Alternative (1)iron sucrose decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• isavuconazonium sulfate

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

• isotretinoin

  Serious - Use Alternative (1)isotretinoin, doxycycline. Mechanism: unknown. Contraindicated. Risk of pseudotumor cerebri.

• ivabradine

  Serious - Use Alternative (1)doxycycline will increase the level or effect of ivabradine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of ivabradine with moderate CYP3A4 inhibitors.

• ivosidenib

  Monitor Closely (1)doxycycline will increase the level or effect of ivosidenib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration with moderate CYP3A4 inhibitors may increase ivosidenib plasma concentrations, thus increasing the risk of QTc prolongation. Monitor for increased risk of QTc interval prolongation.

• lanthanum carbonate

  Monitor Closely (1)lanthanum carbonate decreases levels of doxycycline by cation binding in GI tract. Use Caution/Monitor. Administer oral tetracycline antibiotics at least 2 hr before or after lanthanum. Interaction applies only to oral tetracyclines.

• lefamulin

  Monitor Closely (1)doxycycline will increase the level or effect of lefamulin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor for adverse effects if lefamulin is coadministered with moderate CYP3A inhibitors.

• lemborexant

  Serious - Use Alternative (1)doxycycline will increase the level or effect of lemborexant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of lemborexant with moderate or strong CYP3A inhibitors.

• levamlodipine

  Monitor Closely (1)doxycycline will increase the level or effect of levamlodipine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Coadministration with moderate and strong CYP3A inhibitors results in increased systemic exposure to amlodipine and may require dose reduction. Monitor for symptoms of hypotension and edema when amlodipine is coadministered with CYP3A inhibitors to determine the need for dose adjustment.

• levonorgestrel oral/ethinylestradiol/ferrous bisglycinate

  Monitor Closely (1)doxycycline will decrease the level or effect of levonorgestrel oral/ethinylestradiol/ferrous bisglycinate 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.

• lomitapide

  Contraindicated (1)doxycycline increases levels of lomitapide by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Increases lomitapide levels several folds.

• lonafarnib

  Contraindicated (1)doxycycline will increase the level or effect of lonafarnib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Contraindicated. Lonafarnib is a sensitive CYP3A4 substrate. Coadministration with strong or moderate CYP3A4 inhibitors is contraindicated.

• lumateperone

  Monitor Closely (1)doxycycline will increase the level or effect of lumateperone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce lumateperone dose to 21 mg/day if coadministered with moderate CYP3A4 inhibitors.

• lurbinectedin

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

• magnesium chloride

  Serious - Use Alternative (1)magnesium chloride decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• magnesium citrate

  Serious - Use Alternative (1)magnesium citrate decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• magnesium hydroxide

  Serious - Use Alternative (1)magnesium hydroxide decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• magnesium oxide

  Serious - Use Alternative (1)magnesium oxide decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• magnesium sulfate

  Serious - Use Alternative (1)magnesium sulfate decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• magnesium supplement

  Monitor Closely (1)magnesium supplement will decrease the level or effect of doxycycline by Other (see comment). Modify Therapy/Monitor Closely. Formation of an insoluble complex reduces absorption of the drug through intestinal tract; administer magnesium 2hr before the tetracycline or 4hr after the tetracycline.

• mavacamten

  Monitor Closely (1)doxycycline will increase the level or effect of mavacamten by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Inititiation of moderate CYP3A4 inhibitors may require decreased mavacamten dose.

• mefloquine

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

• mestranol

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

• methotrexate

  Monitor Closely (1)doxycycline increases levels of methotrexate by decreasing elimination. Use Caution/Monitor. Tetracyclines may decrease intestinal absorption of methotrexate or interfere with the enterohepatic circulation by inhibiting bowel flora and suppressing metabolism of the drug by bacteria.

• methoxsalen

  Monitor Closely (1)methoxsalen, doxycycline. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Additive photosensitizing effects.

• methoxyflurane

  Serious - Use Alternative (1)doxycycline, methoxyflurane. Mechanism: pharmacodynamic synergism. Avoid or Use Alternate Drug. Risk of nephrotoxicity.

• methyl aminolevulinate

  Serious - Use Alternative (1)doxycycline, methyl aminolevulinate. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Each drug may increase the photosensitizing effect of the other.

• microbiota oral

  Serious - Use Alternative (1)doxycycline decreases effects of microbiota oral by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Microbiota oral contains bacterial spores. Antibacterial agents may decrease efficacy if coadministered. Complete antibiotic regimens 2-4 days before initiating microbiota oral. .

• midazolam intranasal

  Serious - Use Alternative (1)doxycycline will increase the level or effect of midazolam intranasal by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Coadministration of moderate CYP3A4 inhibitors with midazolam intranasal causes higher midazolam systemic exposure, which may prolong sedation.

• mipomersen

  Monitor Closely (1)mipomersen, doxycycline. Either increases toxicity of the other by Other (see comment). Use Caution/Monitor. Comment: Both drugs have potential to increase hepatic enzymes; monitor LFTs.

• mobocertinib

  Serious - Use Alternative (1)doxycycline will increase the level or effect of mobocertinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If use of moderate CYP3A4 inhibitor unavoidable, reduce mobocertinib dose by ~50% (eg, 160 to 80 mg); closely monitor QTc interval.

• nafcillin

  Serious - Use Alternative (1)doxycycline decreases effects of nafcillin by pharmacodynamic antagonism. Avoid or Use Alternate Drug. bacteriostatic antibiotics may interfere with the bactericidal actions of penicillins.

• naldemedine

  Monitor Closely (1)doxycycline increases levels of naldemedine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Monitor naldemedine for potential adverse effects if coadministered with strong or moderate CYP3A4 inhibitors.

• naloxegol

  Serious - Use Alternative (1)doxycycline will increase the level or effect of naloxegol by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministation of naloxegol with moderate CYP3A4 inhibitors is unavoidable, reduce naloxegol dose to 12.5 mg qDay

• neratinib

  Serious - Use Alternative (1)doxycycline will increase the level or effect of neratinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of neratinib with strong/moderate CYP3A4 inhibitors.

• niacin

  Minor (1)doxycycline will decrease the level or effect of niacin by altering intestinal flora. Applies only to oral form of both agents. Minor/Significance Unknown.

• olaparib

  Serious - Use Alternative (1)doxycycline will increase the level or effect of olaparib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration with moderate CYP3A inhibitors cannot be avoided, reduce olaparib dose to 200 mg (capsule) or 150 mg (tablet) PO BID. Do not substitute tablets with capsules.

• oliceridine

  Monitor Closely (1)doxycycline will increase the level or effect of oliceridine by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. If concomitant use is necessary, may require less frequent oliceridine dosing. Closely monitor for respiratory depression and sedation and titrate subsequent doses accordingly. If inhibitor is discontinued, consider increase oliceridine dosage until stable drug effects are achieved. Monitor for signs of opioid withdrawal.

• omaveloxolone

  Serious - Use Alternative (1)doxycycline will increase the level or effect of omaveloxolone by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If unavoidable, reduce omaveloxolone dose to 100 mg/day. Closely monitor for adverse effects. If adverse effects emerge, further reduce to 50 mg/day.

• onabotulinumtoxinA

  Serious - Use Alternative (1)doxycycline increases effects of onabotulinumtoxinA by pharmacodynamic synergism. Avoid or Use Alternate Drug. Risk of respiratory depression.

• ospemifene

  Monitor Closely (1)doxycycline, ospemifene. Either increases levels of the other by plasma protein binding competition. Modify Therapy/Monitor Closely.

• oxacillin

  Serious - Use Alternative (1)doxycycline decreases effects of oxacillin by pharmacodynamic antagonism. Avoid or Use Alternate Drug. bacteriostatic agents may inhibit the effects of bactericidal agents.

• oxcarbazepine

  Minor (1)oxcarbazepine decreases levels of doxycycline by increasing metabolism. Minor/Significance Unknown.

• pacritinib

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

• palbociclib

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

• pancuronium

  Serious - Use Alternative (1)doxycycline increases effects of pancuronium by pharmacodynamic synergism. Avoid or Use Alternate Drug. Risk of respiratory depression.

• pantothenic acid

  Minor (1)doxycycline will decrease the level or effect of pantothenic acid by altering intestinal flora. Applies only to oral form of both agents. Minor/Significance Unknown.

• pemigatinib

  Serious - Use Alternative (1)doxycycline will increase the level or effect of pemigatinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration with strong or moderate CYP3A4 inhibitors is unavoidable, reduce pemigatinib dose (refer to drug monograph dosage modifications). After discontinuing the CYP3A4 inhibitor for 3 elimination half-lives, may resume previous pemigatinib dose.

• penicillin G aqueous

  Serious - Use Alternative (1)doxycycline decreases effects of penicillin G aqueous by pharmacodynamic antagonism. Avoid or Use Alternate Drug.

• penicillin VK

  Serious - Use Alternative (1)doxycycline decreases effects of penicillin VK by pharmacodynamic antagonism. Avoid or Use Alternate Drug.

• pentobarbital

  Monitor Closely (1)pentobarbital decreases levels of doxycycline by increasing metabolism. Use Caution/Monitor.

• pexidartinib

  Serious - Use Alternative (1)doxycycline will increase the level or effect of pexidartinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration with strong or moderate CYP3A4 inhibitors is unavoidable, reduce pexidartinib dose (refer to drug monograph dosage modifications). After discontinuing the CYP3A4 inhibitor for 3 elimination half-lives, may resume previous pexidartinib dose.

• phenindione

  Minor (1)doxycycline increases effects of phenindione by pharmacodynamic synergism. Minor/Significance Unknown.

• phenobarbital

  Monitor Closely (1)phenobarbital decreases levels of doxycycline by increasing metabolism. Use Caution/Monitor.

• phenytoin

  Minor (1)phenytoin decreases levels of doxycycline by increasing metabolism. Minor/Significance Unknown.

• piperacillin

  Monitor Closely (1)doxycycline decreases effects of piperacillin by pharmacodynamic antagonism. Use Caution/Monitor. bacteriostatic agents may inhibit the effects of bactericidal agents.

• pivmecillinam

  Serious - Use Alternative (1)doxycycline decreases effects of pivmecillinam by pharmacodynamic antagonism. Avoid or Use Alternate Drug.

• polycarbophil

  Monitor Closely (1)polycarbophil decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.

• polysaccharide iron

  Serious - Use Alternative (1)polysaccharide iron decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• porfimer

  Monitor Closely (1)doxycycline, porfimer. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Enhanced photosensitivity.

• primidone

  Monitor Closely (1)primidone decreases levels of doxycycline by increasing metabolism. Use Caution/Monitor.

• protamine

  Minor (1)doxycycline increases effects of protamine by pharmacodynamic synergism. Minor/Significance Unknown.

• pyridoxine

  Minor (1)doxycycline will decrease the level or effect of pyridoxine by altering intestinal flora. Applies only to oral form of both agents. Minor/Significance Unknown.

• pyridoxine (Antidote)

  Minor (1)doxycycline will decrease the level or effect of pyridoxine (Antidote) by altering intestinal flora. Applies only to oral form of both agents. Minor/Significance Unknown.

• rapacuronium

  Serious - Use Alternative (1)doxycycline increases effects of rapacuronium by pharmacodynamic synergism. Avoid or Use Alternate Drug. Risk of respiratory depression.

• rifabutin

  Minor (1)rifabutin decreases levels of doxycycline by increasing metabolism. Minor/Significance Unknown.

• rimegepant

  Monitor Closely (1)doxycycline will increase the level or effect of rimegepant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Avoid repeating rimegepant dose within 48 hr if coadministered with a moderate CYP3A4 inhibitor.

• rocuronium

  Serious - Use Alternative (1)doxycycline increases effects of rocuronium by pharmacodynamic synergism. Avoid or Use Alternate Drug. Risk of respiratory depression.

• rose hips

  Serious - Use Alternative (1)rose hips decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.Minor (1)doxycycline decreases levels of rose hips by increasing elimination. Minor/Significance Unknown.

• ruxolitinib

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

• ruxolitinib topical

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

• secobarbital

  Monitor Closely (1)secobarbital decreases levels of doxycycline by increasing metabolism. Use Caution/Monitor.

• selumetinib

  Serious - Use Alternative (1)doxycycline will increase the level or effect of selumetinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If coadministration with strong or moderate CYP3A4 inhibitors cannot be avoided, reduce selumetinib dosage (refer to selumetinib monograph for further information). After discontinuation of the strong or moderate CYP3A4 inhibitor for 3 elimination half-lives, resume selumetinib dose that was taken before initiating the inhibitor.

• siponimod

  Serious - Use Alternative (1)doxycycline will increase the level or effect of siponimod by affecting hepatic enzyme CYP2E1 metabolism. Avoid or Use Alternate Drug. Coadministration of siponimod with a moderate or strong CYP3A4 inhibitor PLUS a moderate or strong CYP2C9 inhibitor is not recommended.

• sodium bicarbonate

  Serious - Use Alternative (1)sodium bicarbonate decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Separate by 2 hours.

• sodium citrate/citric acid

  Serious - Use Alternative (1)sodium citrate/citric acid decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Separate by 2 hours.

• sodium picosulfate/magnesium oxide/anhydrous citric acid

  Monitor Closely (2)doxycycline decreases effects of sodium picosulfate/magnesium oxide/anhydrous citric acid by altering metabolism. Use Caution/Monitor. Coadministration with antibiotics decreases efficacy by altering colonic bacterial flora needed to convert sodium picosulfate to active drug.
  
  sodium picosulfate/magnesium oxide/anhydrous citric acid decreases levels of doxycycline by cation binding in GI tract. Use Caution/Monitor. Take at least 2 hours before and not less than 6 hours after administration of sodium picosulfate, magnesium oxide and anhydrous citric acid to avoid magnesium chelation.

• sodium sulfate/?magnesium sulfate/potassium chloride

  Serious - Use Alternative (1)sodium sulfate/?magnesium sulfate/potassium chloride decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Administer tetracyclines at least 2 hr before and no less than 6 hr after each dose to avoid chelation with magnesium. .

• sodium sulfate/potassium sulfate/magnesium sulfate

  Serious - Use Alternative (1)sodium sulfate/potassium sulfate/magnesium sulfate decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Administer tetracyclines at least 2 hr before and no less than 6 hr after each dose to avoid chelation with magnesium. .

• sonidegib

  Monitor Closely (1)doxycycline will increase the level or effect of sonidegib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Avoid coadministration of sonidegib with moderate CYP3A4 inhibitors. If a moderate CYP3A inhibitor must be used, administer the moderate CYP3A inhibitor for <14 days and monitor closely for adverse reactions, particularly musculoskeletal adverse reactions.

• sparsentan

  Monitor Closely (1)doxycycline will increase the level or effect of sparsentan by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. No dosage adjustment needed. Monitor blood pressure, serum potassium, edema, and kidney function regularly if sparsentan is coadministered with moderate CYP3A4 inhibitors.

• strontium ranelate

  Serious - Use Alternative (1)strontium ranelate decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Contraindicated. Suspend strontium ranelate during antibiotic therapy.

• succinylcholine

  Serious - Use Alternative (1)doxycycline increases effects of succinylcholine by pharmacodynamic synergism. Avoid or Use Alternate Drug. Risk of respiratory depression.

• sucralfate

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

• sucroferric oxyhydroxide

  Monitor Closely (1)sucroferric oxyhydroxide decreases levels of doxycycline by drug binding in GI tract. Use Caution/Monitor. Do not administer at the same time; take doxycycline at least 1 hr before sucroferric oxyhydroxide.

• sufentanil SL

  Monitor Closely (1)doxycycline will increase the level or effect of sufentanil SL by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Coadministration of sufentanil SL with any CYP3A4 inhibitor may increase sufentanil plasma concentration, and, thereby increase or prolonged adverse effects, including potentially fatal respiratory depression.

• suvorexant

  Monitor Closely (1)doxycycline will increase the level or effect of suvorexant by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Decrease suvorexant starting dose to 5 mg HS if coadministered with moderate CYP3A4 inhibitors

• tamsulosin

  Monitor Closely (1)doxycycline increases levels of tamsulosin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. Dose reduction may be needed for coadministered drugs that are predominantly metabolized by CYP3A.

• tazemetostat

  Serious - Use Alternative (1)doxycycline will increase the level or effect of tazemetostat by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of tazemetostat with moderate CYP3A4 inhibitors. If coadministration is unavoidable, reduce tazemetostat current dose (see drug monograph Dosage Modifications).

• temocillin

  Serious - Use Alternative (1)doxycycline decreases effects of temocillin by pharmacodynamic antagonism. Avoid or Use Alternate Drug.

• tezacaftor

  Monitor Closely (1)doxycycline will increase the level or effect of tezacaftor by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Adjust tezacaftor dosage regimen if coadministered with a moderate CYP3A inhibitor.

• thiamine

  Minor (1)doxycycline will decrease the level or effect of thiamine by altering intestinal flora. Applies only to oral form of both agents. Minor/Significance Unknown.

• ticarcillin

  Serious - Use Alternative (1)doxycycline decreases effects of ticarcillin by pharmacodynamic antagonism. Avoid or Use Alternate Drug.

• tinidazole

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

• tofacitinib

  Monitor Closely (1)doxycycline increases levels of tofacitinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Use Caution/Monitor. No specific dose adjustment recommended when tofacitinib coadministered with moderate CYP3A4 inhibitors; decrease tofacitinib dose if coadministered with both moderate CYP3A4 and potent CYP2C19 inhibitors.

• trabectedin

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

• tretinoin

  Contraindicated (1)doxycycline, tretinoin. Either increases toxicity of the other by unspecified interaction mechanism. Contraindicated. Both tretinoin and tetracyclines can cause increased intracranial pressure.Serious - Use Alternative (1)doxycycline, tretinoin. Either increases levels of the other by Mechanism: pharmacodynamic synergism. Avoid or Use Alternate Drug. Increased phototoxicity.

• tretinoin topical

  Serious - Use Alternative (1)doxycycline, tretinoin topical. Mechanism: pharmacodynamic synergism. Avoid or Use Alternate Drug. Increased phototoxicity.

• trimagnesium citrate anhydrous

  Monitor Closely (1)trimagnesium citrate anhydrous decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Multivalent cation-containing products may reduce bioavailability of tetracyclines; administer tetracycline at least 2 hr before or 6 hr after magnesium; use alternatives if available.

• tripotassium dicitratobismuthate

  Serious - Use Alternative (1)tripotassium dicitratobismuthate decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

• typhoid vaccine live

  Serious - Use Alternative (1)doxycycline decreases effects of typhoid vaccine live by pharmacodynamic antagonism. Contraindicated. Wait until Abx Tx complete to administer live bacterial vaccine.

• vardenafil

  Monitor Closely (1)doxycycline will increase the level or effect of vardenafil by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Vardenafil dose may need to be reduced if coadministered with moderate or strong CYP3A4 inhibitors

• vecuronium

  Serious - Use Alternative (1)doxycycline increases effects of vecuronium by pharmacodynamic synergism. Avoid or Use Alternate Drug. Risk of respiratory depression.

• venetoclax

  Serious - Use Alternative (1)doxycycline will increase the level or effect of venetoclax by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. If a moderate CYP3A inhibitor must be used, reduce the venetoclax dose by at least 50%. Monitor more closely for signs of venetoclax toxicities.

• verteporfin

  Minor (1)doxycycline, verteporfin. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Increased phototoxicity.

• voclosporin

  Monitor Closely (1)doxycycline will increase the level or effect of voclosporin by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce voclosporin daily dosage to 15.8 mg PO in AM and 7.9 mg PO in PM.

• warfarin

  Monitor Closely (1)doxycycline increases effects of warfarin by unspecified interaction mechanism. Use Caution/Monitor.

• zanubrutinib

  Monitor Closely (1)doxycycline will increase the level or effect of zanubrutinib by affecting hepatic/intestinal enzyme CYP3A4 metabolism. Modify Therapy/Monitor Closely. Reduce zanubrutinib (a CYP3A4 substrate) to 80 mg PO BID to when coadministered with a moderate CYP3A4 inhibitor. Interrupt dose as recommended for adverse reactions. After discontinuing the CYP3A4 inhibitor, resume previous dose of zanubrutinib.

• zinc

  Monitor Closely (1)zinc will decrease the level or effect of doxycycline by cation binding in GI tract. Modify Therapy/Monitor Closely. Separate administration of oral tetracycline derivatives and oral zinc salts by at least 2 hr.