Dosing & Uses
Dosage Forms & Strengths
capsule
- 1mg
- 2mg
- 5mg
Hypertension
Initial: 1 mg PO q8-12hr
Maintenance: 6-15 mg/day divided 2 or 3 times daily; alternatively, 1-5 mg PO BID; may increase dose to 20 mg/day in divided doses; some patients may benefit from up to 40 mg/day in divided doses
PTSD-Related Nightmares & Sleep Disruption (Off-label)
Initial: 1 mg PO qHS
Maintenance: 1 mg PO qHS initially; may increase dose to 2 mg qHS; adjust dose based on response and tolerability in 1-2 mg increments q7days; not to exceed 15 mg/day
Benign Prostate Hypertrophy (Off-label)
Initial: 0.5 mg PO q12hr
Maintenance: 2 mg PO q12hr
Raynaud Phenomenon (Off-label)
0.5-1 mg PO qDay (HS) or 0.5 mg PO BID; adjust dose based on response and tolerability up to 12 mg/day divided BID/TID
Administration
Give first dose and subsequent increases at bedtime to avoid syncope
Okay with food
Interactions
Interaction Checker
No Results
Contraindicated
Serious - Use Alternative
Significant - Monitor Closely
Minor
Contraindicated (0)
Serious - Use Alternative (6)
- bremelanotide
bremelanotide will decrease the level or effect of prazosin by Other (see comment). Avoid or Use Alternate Drug. Bremelanotide may slow gastric emptying and potentially reduces the rate and extent of absorption of concomitantly administered oral medications. Avoid use when taking any oral drug that is dependent on threshold concentrations for efficacy. Interactions listed are representative examples and do not include all possible clinical examples.
- lofexidine
lofexidine, prazosin. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Avoid coadministration with other drugs that decrease pulse or blood pressure to mitigate risk of excessive bradycardia and hypotension.
- sildenafil
sildenafil increases effects of prazosin by pharmacodynamic synergism. Avoid or Use Alternate Drug. Risk of hypotension; separate sildenafil >25mg from alpha blocker by 4hr.
- tamsulosin
prazosin, tamsulosin. Either increases effects of the other by additive vasodilation. Avoid or Use Alternate Drug. Risk of hypotension.
- vardenafil
vardenafil increases effects of prazosin by pharmacodynamic synergism. Contraindicated. Risk of hypotension.
- yohimbe
yohimbe increases effects of prazosin by pharmacodynamic synergism. Contraindicated.
Monitor Closely (99)
- acebutolol
prazosin and acebutolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely. The severity and duration of hypotension following the first dose of prazosin may be enhanced.
- aceclofenac
aceclofenac decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- acemetacin
acemetacin decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- aldesleukin
aldesleukin increases effects of prazosin by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.
- alfuzosin
alfuzosin and prazosin both increase anti-hypertensive channel blocking. Use Caution/Monitor.
- amifostine
amifostine, prazosin. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration with blood pressure lowering agents may increase the risk and severity of hypotension associated with amifostine. When amifostine is used at chemotherapeutic doses, withhold blood pressure lowering medications for 24 hr prior to amifostine; if blood pressure lowering medication cannot be withheld, do not administer amifostine.
- amlodipine
prazosin and amlodipine both increase anti-hypertensive channel blocking. Use Caution/Monitor.
- asenapine
asenapine and prazosin both increase anti-hypertensive channel blocking. Use Caution/Monitor.
- aspirin
aspirin decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- aspirin rectal
aspirin rectal decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- aspirin/citric acid/sodium bicarbonate
aspirin/citric acid/sodium bicarbonate decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- atenolol
prazosin and atenolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.
- avanafil
avanafil increases effects of prazosin by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.
- benazepril
benazepril, prazosin. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Exaggerated first dose hypotensive response.
- betaxolol
prazosin and betaxolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.
- bisoprolol
prazosin and bisoprolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.
- bretylium
prazosin, bretylium. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Each drug may cause hypotension.
- captopril
captopril, prazosin. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Exaggerated first dose hypotensive response.
- carbidopa
carbidopa increases effects of prazosin by pharmacodynamic synergism. Use Caution/Monitor. Therapy with carbidopa, given with or without levodopa or carbidopa-levodopa combination products, is started, dosage adjustment of the antihypertensive drug may be required.
- carvedilol
prazosin and carvedilol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.
- celecoxib
celecoxib decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- celiprolol
prazosin and celiprolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.
- choline magnesium trisalicylate
choline magnesium trisalicylate decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- clevidipine
prazosin and clevidipine both increase anti-hypertensive channel blocking. Use Caution/Monitor.
- clonidine
clonidine, prazosin. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Sympatholytic action may worsen sinus node dysfunction and atrioventricular (AV) block.
- diclofenac
diclofenac decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- diflunisal
diflunisal decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- diltiazem
prazosin and diltiazem both increase anti-hypertensive channel blocking. Use Caution/Monitor.
- doxazosin
doxazosin and prazosin both increase anti-hypertensive channel blocking. Use Caution/Monitor.
- dulaglutide
dulaglutide, prazosin. Other (see comment). Use Caution/Monitor. Comment: Dulaglutide slows gastric emptying and may impact absorption of concomitantly administered oral medications; be particularly cautious when coadministered with drugs that have a narrow therapeutic index.
- enalapril
enalapril, prazosin. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Exaggerated first dose hypotensive response.
- esmolol
prazosin and esmolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely. The severity and duration of hypotension following the first dose of prazosin may be enhanced.
- etodolac
etodolac decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- felodipine
prazosin and felodipine both increase anti-hypertensive channel blocking. Use Caution/Monitor.
- fenoprofen
fenoprofen decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- ferric maltol
ferric maltol, prazosin. Either increases levels of the other by unspecified interaction mechanism. Modify Therapy/Monitor Closely. Coadministration of ferric maltol with certain oral medications may decrease the bioavailability of either ferric maltol and some oral drugs. For oral drugs where reductions in bioavailability may cause clinically significant effects on its safety or efficacy, separate administration of ferric maltol from these drugs. Duration of separation may depend on the absorption of the medication concomitantly administered (eg, time to peak concentration, whether the drug is an immediate or extended release product).
- flurbiprofen
flurbiprofen decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- fosinopril
fosinopril, prazosin. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Exaggerated first dose hypotensive response.
- fostamatinib
fostamatinib will increase the level or effect of prazosin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor. Concomitant use of fostamatinib may increase concentrations of P-gp substrates. Monitor for toxicities of the P-gp substrate drug that may require dosage reduction when given concurrently with fostamatinib.
- glecaprevir/pibrentasvir
glecaprevir/pibrentasvir will increase the level or effect of prazosin by P-glycoprotein (MDR1) efflux transporter. Use Caution/Monitor.
- ibuprofen
ibuprofen decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- ibuprofen IV
ibuprofen IV decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- iloperidone
iloperidone increases effects of prazosin by pharmacodynamic synergism. Use Caution/Monitor.
- imidapril
imidapril, prazosin. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Exaggerated first dose hypotensive response.
- indomethacin
indomethacin decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- isradipine
prazosin and isradipine both increase anti-hypertensive channel blocking. Use Caution/Monitor.
- ketoprofen
ketoprofen decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- ketorolac
ketorolac decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- ketorolac intranasal
ketorolac intranasal decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- labetalol
prazosin and labetalol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.
- levodopa
levodopa increases effects of prazosin by pharmacodynamic synergism. Use Caution/Monitor. Consider decreasing dosage of antihypertensive agent.
- lisinopril
lisinopril, prazosin. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Exaggerated first dose hypotensive response.
- lornoxicam
lornoxicam decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- lurasidone
lurasidone increases effects of prazosin by Other (see comment). Use Caution/Monitor. Comment: Potential for increased risk of hypotension with concurrent use. Monitor blood pressure and adjust dose of antihypertensive agent as needed.
- maraviroc
maraviroc, prazosin. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Increased risk of orthostatic hypotension.
- meclofenamate
meclofenamate decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- mefenamic acid
mefenamic acid decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- meloxicam
meloxicam decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- methylphenidate
methylphenidate will decrease the level or effect of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. Methylphenidate may diminish antihypertensive effects. Monitor BP.
- metoprolol
prazosin and metoprolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.
- moexipril
moexipril, prazosin. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Exaggerated first dose hypotensive response.
- moxisylyte
moxisylyte and prazosin both increase anti-hypertensive channel blocking. Use Caution/Monitor.
- nabumetone
nabumetone decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- nadolol
prazosin and nadolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.
- naproxen
naproxen decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- nebivolol
prazosin and nebivolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.
- nicardipine
prazosin and nicardipine both increase anti-hypertensive channel blocking. Use Caution/Monitor.
- nifedipine
prazosin and nifedipine both increase anti-hypertensive channel blocking. Use Caution/Monitor.
- nisoldipine
prazosin and nisoldipine both increase anti-hypertensive channel blocking. Use Caution/Monitor.
- nitroglycerin rectal
nitroglycerin rectal, prazosin. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Observe for possible additive hypotensive effects during concomitant use. .
- oxaprozin
oxaprozin decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- oxymetazoline topical
oxymetazoline topical increases and prazosin decreases sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Effect of interaction is not clear, use caution. Use Caution/Monitor.
- parecoxib
parecoxib decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- penbutolol
prazosin and penbutolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.
- perindopril
perindopril, prazosin. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Exaggerated first dose hypotensive response.
- phenoxybenzamine
phenoxybenzamine and prazosin both increase anti-hypertensive channel blocking. Use Caution/Monitor.
- phentolamine
phentolamine and prazosin both increase anti-hypertensive channel blocking. Use Caution/Monitor.
- pindolol
prazosin and pindolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.
- piroxicam
piroxicam decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- propranolol
prazosin and propranolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely. The severity and duration of hypotension following the first dose of prazosin may be enhanced.
- quinapril
quinapril, prazosin. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Exaggerated first dose hypotensive response.
- ramipril
ramipril, prazosin. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Exaggerated first dose hypotensive response.
- ropeginterferon alfa 2b
ropeginterferon alfa 2b will increase the level or effect of prazosin by Other (see comment). Use Caution/Monitor. Certain proinflammatory cytokines, including interferons, can suppress CYP450 enzymes resulting in increased exposures of some CYP substrates. Therefore, monitor patients who are receiving concomitant drugs that are CYP450 substrates with a narrow therapeutic index from toxicities to such drugs.
- salicylates (non-asa)
salicylates (non-asa) decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- salsalate
salsalate decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- silodosin
prazosin and silodosin both increase anti-hypertensive channel blocking. Use Caution/Monitor.
- sotalol
prazosin and sotalol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely. The severity and duration of hypotension following the first dose of prazosin may be enhanced.
- sulfasalazine
sulfasalazine decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- sulindac
sulindac decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- tadalafil
tadalafil increases effects of prazosin by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.
- teduglutide
teduglutide increases levels of prazosin by Other (see comment). Use Caution/Monitor. Comment: Teduglutide may increase absorption of concomitant PO medications; caution with with drugs requiring titration or those with a narrow therapeutic index; dose adjustment may be necessary.
- terazosin
prazosin and terazosin both increase anti-hypertensive channel blocking. Use Caution/Monitor.
- timolol
prazosin and timolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.
- tolfenamic acid
tolfenamic acid decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- tolmetin
tolmetin decreases effects of prazosin by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.
- trandolapril
trandolapril, prazosin. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Exaggerated first dose hypotensive response.
- ustekinumab
ustekinumab, prazosin. Other (see comment). Use Caution/Monitor. Comment: Formation of CYP450 enzymes can be altered by increased levels of certain cytokines during chronic inflammation; thus, normalizing the formation of CYP450 enzymes. Upon initiation or discontinuation of ustekinumab in patients who are receiving concomitant CYP450 substrates, particularly those with a narrow therapeutic index, consider monitoring for therapeutic effect.
- verapamil
prazosin and verapamil both increase anti-hypertensive channel blocking. Use Caution/Monitor.
- zotepine
prazosin and zotepine both increase anti-hypertensive channel blocking. Use Caution/Monitor.
Minor (7)
- brimonidine
brimonidine increases effects of prazosin by pharmacodynamic synergism. Minor/Significance Unknown.
- butcher's broom
prazosin, butcher's broom. Either decreases effects of the other by Mechanism: pharmacodynamic antagonism. Minor/Significance Unknown.
- ethanol
prazosin, ethanol. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypotension, esp. in Asian pts.
- phenylephrine
prazosin, phenylephrine. Either decreases effects of the other by Mechanism: pharmacodynamic antagonism. Minor/Significance Unknown.
- phenylephrine PO
prazosin, phenylephrine PO. Either decreases effects of the other by Mechanism: pharmacodynamic antagonism. Minor/Significance Unknown.
- tizanidine
tizanidine increases effects of prazosin by pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypotension.
- treprostinil
treprostinil increases effects of prazosin by pharmacodynamic synergism. Minor/Significance Unknown.
Adverse Effects
1-10%
Dizziness (10%)
Drowsiness (8%)
Headache (8%)
Weakness (7%)
Asthenia (6.5%)
Nausea (5%)
Palpitation (5%)
Frequency Not Defined (Selected)
Edema
Orthostatic hypotension
Syncope
Fever
Rash
Abdominal discomfort/pain
Diarrhea
Vomiting
Abnormal liver function tests
Impotence
Pancreatitis
Urinary incontinence
Warnings
Contraindications
Hypersensitivity
Cautions
Risk of syncope; has no relation to plasma prazosin concentration; if syncope occurs, place patient in the recumbent position and treat supportively as necessary
Discontinue if angina symptoms occur or worsen
May cause CNS depression, which may impair physical or internal abilities; use caution when performing tasks that require mental alertness
May impair ability to drive/perform hazardous tasks due to dizziness
History of narcolepsy - May exacerbate
Cataract surgery - Linked to intraoperative floppy iris syndrome
Concomitant administration with PDE-5 inhibitor (eg, sildenafil) can result in additive blood pressure-lowering effects and symptomatic hypotension; initiate PDE-5 inhibitor therapy at lowest dose
First dose effect may occur, causing a sudden and drastic fall in blood pressure after administration of the first dose.
May exacerbate heart failure
Prolonged erections and priapism reported with alpha-1 blockers including prazosin in post marketing experience; if erection persists > 4 hours, seek immediate medical assistance
May cause significant orthostatic hypotension and syncope with sudden loss of consciousness, especially 30-90 min of first dose; may also occur if therapy interrupted for a few days, if dosage rapidly increased or if another antihypertensive drug, like a beta-blocker or vasodilator, or a phosphodiesterase 5 inhibitor is introduced
Prostatic carcinoma should be ruled out before initiating therapy
Geriatric considerations
- Avoid use for hypertension; high risk of orthostatic hypotension (Beers criteria)
- May cause significant orthostatic hypotension and syncope; consider lower initial dose; titrate to response
- Adverse effects such as dry mouth and urinary complications can be bothersome in the elderly
Pregnancy & Lactation
Pregnancy category: C
Lactation: Excreted in breast milk; use caution
Pregnancy Categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk. C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done. D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk. X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist. NA: Information not available.Pharmacology
Mechanism of Action
Alpha-1 blocker inhibits postsynaptic alpha-adrenergic receptors, causing arterial and venous dilation and a subsequent decrease in blood pressure
Absorption
Bioavailability: 43-82%
Onset: ~2 hr
Duration: 10-24 hr
Peak effect: 2-4 hr
Peak plasma time: 2-3 hr
Distribution
Protein bound: 97%
Metabolism
Hepatic metabolization (extensive)
Elimination
Half-life elimination: 2-3 hr
Excretion: Urine (6-10%); rest in feces (via bile)
Images
| BRAND | FORM. | UNIT PRICE | PILL IMAGE |
|---|---|---|---|
| Minipress oral - | 2 mg capsule |  | |
| Minipress oral - | 1 mg capsule |  | |
| Minipress oral - | 5 mg capsule |  | |
| prazosin oral - | 5 mg capsule |  | |
| prazosin oral - | 1 mg capsule |  | |
| prazosin oral - | 2 mg capsule |  | |
| prazosin oral - | 1 mg capsule |  | |
| prazosin oral - | 2 mg capsule |  | |
| prazosin oral - | 2 mg capsule |  | |
| prazosin oral - | 2 mg capsule | | |
| prazosin oral - | 5 mg capsule |  | |
| prazosin oral - | 5 mg capsule | | |
| prazosin oral - | 1 mg capsule | | |
| prazosin oral - | 2 mg capsule |  | |
| prazosin oral - | 2 mg capsule |  | |
| prazosin oral - | 1 mg capsule |  | |
| prazosin oral - | 1 mg capsule |  | |
| prazosin oral - | 5 mg capsule |  | |
| prazosin oral - | 5 mg capsule |  | |
| prazosin oral - | 2 mg capsule |  |
Copyright © 2010 First DataBank, Inc.
Patient Handout
prazosin oral
PRAZOSIN - ORAL
(PRAZ-oh-sin)
COMMON BRAND NAME(S): Minipress
USES: Prazosin is used with or without other medications to treat high blood pressure. Lowering high blood pressure helps prevent strokes, heart attacks, and kidney problems.Prazosin belongs to a class of medications called alpha blockers. It works by relaxing and widening blood vessels so blood can flow more easily.
HOW TO USE: Take this medication by mouth with or without food as directed by your doctor, usually two or three times daily. If stomach upset occurs, take with food or milk. The dosage is based on your age, medical condition and response to therapy.Prazosin can occasionally cause sudden fainting after the first dose and anytime that your dose is increased. To reduce your risk of fainting, the first dose prescribed by your doctor will be the smallest dose available. You should take this first dose as you are going to bed. This will decrease the possibility of fainting. Your dose may be gradually increased. Take your first new dose at bedtime when your dose is increased unless directed otherwise by your doctor.Use this medication regularly in order to get the most benefit from it. To help you remember, take it at the same time(s) each day. If you are taking this medication for high blood pressure, keep taking it even if you feel well. Most people with high blood pressure do not feel sick. It may take up to several weeks before the full benefit of this drug takes effect.Do not stop taking this medication without first consulting your doctor. Some conditions may become worse when the drug is abruptly stopped. Your dose may need to be gradually decreased.Tell your doctor if your condition worsens (such as your routine blood pressure readings increase).
SIDE EFFECTS: Headache, drowsiness, tiredness, weakness, blurred vision, nausea, vomiting, diarrhea, or constipation may occur as your body adjusts to the medication. If any of these effects last or get worse, tell your doctor or pharmacist promptly.Lightheadedness or dizziness upon standing may also occur, especially after the first dose and shortly after taking a dose of the drug during the first week of treatment. To reduce the risk of dizziness and fainting, get up slowly when rising from a seated or lying position. If dizziness occurs, sit or lie down right away. Your dose may need to be adjusted.Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.Tell your doctor right away if you have any serious side effects, including: pounding heartbeat, fainting, frequent urination, mental/mood changes (such as depression), swelling of the feet/ankles.Rarely, males may have a painful or prolonged erection lasting 4 or more hours. If this occurs, stop using this drug and get medical help right away, or permanent problems could occur.A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.In the US -Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.
PRECAUTIONS: Before taking prazosin, tell your doctor or pharmacist if you are allergic to it; or to other alpha blockers (such as doxazosin, terazosin); or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.Before using this medication, tell your doctor or pharmacist your medical history, especially of: heart problems (such as low blood pressure), kidney disease, uncontrolled attacks of deep sleep (narcolepsy), prostate cancer, certain eye problems (cataracts, glaucoma).This drug may make you dizzy or drowsy or blur your vision. Alcohol or marijuana (cannabis) can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness or clear vision until you can do it safely. Do not drive or participate in hazardous activities for 24 hours after your first dose, any increase in your dosage, or restarting treatment. If your doctor prescribes any additional blood pressure drugs, avoid driving and hazardous activities for 24 hours after your first dose of the new medication. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).To reduce the risk of dizziness and fainting, be careful when standing for long periods. Avoid getting overheated during exercise and hot weather. When first starting this drug, avoid situations where you may be injured if you faint.Before having surgery (including cataract/glaucoma eye surgery), tell your doctor or dentist if you are taking or have ever taken this medication, and about all the other products you use (including prescription drugs, nonprescription drugs, and herbal products).Older adults may be more sensitive to the side effects of this drug, especially dizziness and fainting. These side effects can increase the risk of falling.During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.Prazosin passes into breast milk. Consult your doctor before breast-feeding.
DRUG INTERACTIONS: Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.Some products that may interact with this drug include: other alpha blocker drugs (such as doxazosin, terazosin), beta blockers (such as atenolol, metoprolol, propranolol), drugs to treat erectile dysfunction-ED or pulmonary hypertension (such as sildenafil, tadalafil).Tell your doctor or pharmacist if you are taking other products that cause drowsiness such as opioid pain or cough relievers (such as codeine, hydrocodone), alcohol, marijuana (cannabis), drugs for sleep or anxiety (such as alprazolam, lorazepam, zolpidem), muscle relaxants (such as carisoprodol, cyclobenzaprine), or antihistamines (such as cetirizine, diphenhydramine).Check the labels on all your medicines (such as allergy or cough-and-cold products) because they may contain ingredients that cause drowsiness. Ask your pharmacist about using those products safely.Some products have ingredients that could raise your heart rate or blood pressure. Tell your pharmacist what products you are using, and ask how to use them safely (especially cough-and-cold products, diet aids, or NSAIDs such as ibuprofen/naproxen).This medication may interfere with certain laboratory tests (including pheochromocytoma screening test), possibly causing false test results. Make sure laboratory personnel and all your doctors know you use this drug.
OVERDOSE: If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose may include: severe drowsiness, slow reactions.
NOTES: Do not share this medication with others.Lifestyle changes such as stress reduction programs, exercise, and dietary changes may increase the effectiveness of this medicine. Talk to your doctor or pharmacist about lifestyle changes that might benefit you.Have your blood pressure and heart rate checked regularly while taking this medication. Learn how to monitor your own blood pressure, and share the results with your doctor.
MISSED DOSE: If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.
STORAGE: Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets.Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.
Information last revised February 2022. Copyright(c) 2022 First Databank, Inc.
IMPORTANT: HOW TO USE THIS INFORMATION: This is a summary and does NOT have all possible information about this product. This information does not assure that this product is safe, effective, or appropriate for you. This information is not individual medical advice and does not substitute for the advice of your health care professional. Always ask your health care professional for complete information about this product and your specific health needs.
Formulary
Adding plans allows you to compare formulary status to other drugs in the same class.
To view formulary information first create a list of plans. Your list will be saved and can be edited at any time.
Adding plans allows you to:
- View the formulary and any restrictions for each plan.
- Manage and view all your plans together – even plans in different states.
- Compare formulary status to other drugs in the same class.
- Access your plan list on any device – mobile or desktop.
