phenoxybenzamine (Rx)

Brand and Other Names:Dibenzyline
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Dosing & Uses

AdultPediatric

Dosage Forms & Strengths

capsule

  • 10mg

Hypertension Pheochromocytoma

10 mg PO q12hr initially; increase qODay to 20-40 mg PO q12hr/q8hr (sometimes higher doses necessary)

Bladder Management (Off-label)

Micturition disorders: 10 mg PO qDay Initially; can be increased q5Day by 10 mg PO q8-12hr

Dosage Forms & Strengths

capsule

  • 10mg

Pheochromocytoma Hypertension (Off-label)

0.25-1 mg/kg PO qDay; increase to effect slowly; not to exceed 10 mg/day  

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Interactions

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              Serious - Use Alternative (5)

              • lofexidine

                lofexidine, phenoxybenzamine. 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 phenoxybenzamine by pharmacodynamic synergism. Avoid or Use Alternate Drug. Risk of hypotension; separate sildenafil >25mg from alpha blocker by 4hr.

              • tamsulosin

                phenoxybenzamine, tamsulosin. Either increases effects of the other by additive vasodilation. Avoid or Use Alternate Drug. Risk of hypotension.

              • vardenafil

                vardenafil increases effects of phenoxybenzamine by pharmacodynamic synergism. Contraindicated. Risk of hypotension.

              • yohimbe

                yohimbe increases effects of phenoxybenzamine by pharmacodynamic synergism. Contraindicated.

              Monitor Closely (102)

              • acebutolol

                phenoxybenzamine and acebutolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

              • aceclofenac

                aceclofenac decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • acemetacin

                acemetacin decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • albuterol

                phenoxybenzamine, albuterol. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Hypotension, tachycardia.

              • aldesleukin

                aldesleukin increases effects of phenoxybenzamine by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.

              • alfuzosin

                alfuzosin and phenoxybenzamine both increase anti-hypertensive channel blocking. Use Caution/Monitor.

              • amifostine

                amifostine, phenoxybenzamine. 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

                phenoxybenzamine and amlodipine both increase anti-hypertensive channel blocking. Use Caution/Monitor.

              • arformoterol

                phenoxybenzamine, arformoterol. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Hypotension, tachycardia.

              • asenapine

                asenapine and phenoxybenzamine both increase anti-hypertensive channel blocking. Use Caution/Monitor.

              • aspirin

                aspirin decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • aspirin rectal

                aspirin rectal decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • aspirin/citric acid/sodium bicarbonate

                aspirin/citric acid/sodium bicarbonate decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • atenolol

                phenoxybenzamine and atenolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

              • avanafil

                avanafil increases effects of phenoxybenzamine by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.

              • benazepril

                benazepril, phenoxybenzamine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Exaggerated first dose hypotensive response.

              • betaxolol

                phenoxybenzamine and betaxolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

              • bisoprolol

                phenoxybenzamine and bisoprolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

              • bretylium

                phenoxybenzamine, bretylium. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Each drug may cause hypotension.

              • captopril

                captopril, phenoxybenzamine. Either increases effects of the other by Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Exaggerated first dose hypotensive response. Both drugs lower blood pressure. Monitor blood pressure.

              • carbidopa

                carbidopa increases effects of phenoxybenzamine by pharmacodynamic synergism. Use Caution/Monitor. Consider decreasing dosage of antihypertensive agent.

              • carvedilol

                phenoxybenzamine and carvedilol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

              • celecoxib

                celecoxib decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • celiprolol

                phenoxybenzamine and celiprolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

              • choline magnesium trisalicylate

                choline magnesium trisalicylate decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • clevidipine

                phenoxybenzamine and clevidipine both increase anti-hypertensive channel blocking. Use Caution/Monitor.

              • diclofenac

                diclofenac decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • diflunisal

                diflunisal decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • diltiazem

                phenoxybenzamine and diltiazem both increase anti-hypertensive channel blocking. Use Caution/Monitor.

              • dobutamine

                phenoxybenzamine, dobutamine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Hypotension, tachycardia.

              • dopexamine

                phenoxybenzamine, dopexamine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Hypotension, tachycardia.

              • doxazosin

                doxazosin and phenoxybenzamine both increase anti-hypertensive channel blocking. Use Caution/Monitor.

              • enalapril

                enalapril, phenoxybenzamine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Exaggerated first dose hypotensive response.

              • ephedrine

                phenoxybenzamine, ephedrine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Hypotension, tachycardia.

              • epinephrine

                phenoxybenzamine, epinephrine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Hypotension, tachycardia.

              • epinephrine racemic

                phenoxybenzamine, epinephrine racemic. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Hypotension, tachycardia.

              • esmolol

                phenoxybenzamine and esmolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

              • etodolac

                etodolac decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • felodipine

                phenoxybenzamine and felodipine both increase anti-hypertensive channel blocking. Use Caution/Monitor.

              • fenoprofen

                fenoprofen decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • flurbiprofen

                flurbiprofen decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • formoterol

                phenoxybenzamine, formoterol. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Hypotension, tachycardia.

              • fosinopril

                fosinopril, phenoxybenzamine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Exaggerated first dose hypotensive response.

              • ibuprofen

                ibuprofen decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • ibuprofen IV

                ibuprofen IV decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • iloperidone

                iloperidone increases effects of phenoxybenzamine by pharmacodynamic synergism. Use Caution/Monitor.

              • imidapril

                imidapril, phenoxybenzamine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Exaggerated first dose hypotensive response.

              • indomethacin

                indomethacin decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • isoproterenol

                phenoxybenzamine, isoproterenol. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Hypotension, tachycardia.

              • isradipine

                phenoxybenzamine and isradipine both increase anti-hypertensive channel blocking. Use Caution/Monitor.

              • ketoprofen

                ketoprofen decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • ketorolac

                ketorolac decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • ketorolac intranasal

                ketorolac intranasal decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • labetalol

                phenoxybenzamine and labetalol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

              • levalbuterol

                phenoxybenzamine, levalbuterol. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Hypotension, tachycardia.

              • lisinopril

                lisinopril, phenoxybenzamine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Exaggerated first dose hypotensive response.

              • lornoxicam

                lornoxicam decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • meclofenamate

                meclofenamate decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • mefenamic acid

                mefenamic acid decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • meloxicam

                meloxicam decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • metaproterenol

                phenoxybenzamine, metaproterenol. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Hypotension, tachycardia.

              • methylphenidate

                methylphenidate will decrease the level or effect of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. Methylphenidate may diminish antihypertensive effects. Monitor BP.

              • metoprolol

                phenoxybenzamine and metoprolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

              • moexipril

                moexipril, phenoxybenzamine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Exaggerated first dose hypotensive response.

              • moxisylyte

                moxisylyte and phenoxybenzamine both increase anti-hypertensive channel blocking. Use Caution/Monitor.

              • nabumetone

                nabumetone decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • nadolol

                phenoxybenzamine and nadolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

              • naproxen

                naproxen decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • nebivolol

                phenoxybenzamine and nebivolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

              • nicardipine

                phenoxybenzamine and nicardipine both increase anti-hypertensive channel blocking. Use Caution/Monitor.

              • nifedipine

                phenoxybenzamine and nifedipine both increase anti-hypertensive channel blocking. Use Caution/Monitor.

              • nisoldipine

                phenoxybenzamine and nisoldipine both increase anti-hypertensive channel blocking. Use Caution/Monitor.

              • norepinephrine

                phenoxybenzamine, norepinephrine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Hypotension, tachycardia.

              • oxaprozin

                oxaprozin decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • oxymetazoline topical

                oxymetazoline topical increases and phenoxybenzamine 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 phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • penbutolol

                phenoxybenzamine and penbutolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

              • perindopril

                perindopril, phenoxybenzamine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Exaggerated first dose hypotensive response.

              • phentolamine

                phenoxybenzamine and phentolamine both increase anti-hypertensive channel blocking. Use Caution/Monitor.

              • pindolol

                phenoxybenzamine and pindolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

              • pirbuterol

                phenoxybenzamine, pirbuterol. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Hypotension, tachycardia.

              • piroxicam

                piroxicam decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • prazosin

                phenoxybenzamine and prazosin both increase anti-hypertensive channel blocking. Use Caution/Monitor.

              • propranolol

                phenoxybenzamine and propranolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

              • quinapril

                quinapril, phenoxybenzamine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Exaggerated first dose hypotensive response.

              • ramipril

                ramipril, phenoxybenzamine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Exaggerated first dose hypotensive response.

              • salicylates (non-asa)

                salicylates (non-asa) decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • salmeterol

                phenoxybenzamine, salmeterol. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Hypotension, tachycardia.

              • salsalate

                salsalate decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • silodosin

                phenoxybenzamine and silodosin both increase anti-hypertensive channel blocking. Use Caution/Monitor.

              • sotalol

                phenoxybenzamine and sotalol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

              • sulfasalazine

                sulfasalazine decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • sulindac

                sulindac decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • tadalafil

                tadalafil increases effects of phenoxybenzamine by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.

              • terazosin

                phenoxybenzamine and terazosin both increase anti-hypertensive channel blocking. Use Caution/Monitor.

              • terbutaline

                phenoxybenzamine, terbutaline. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Hypotension, tachycardia.

              • timolol

                phenoxybenzamine and timolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

              • tolfenamic acid

                tolfenamic acid decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • tolmetin

                tolmetin decreases effects of phenoxybenzamine by pharmacodynamic antagonism. Use Caution/Monitor. NSAIDs decrease prostaglandin synthesis.

              • trandolapril

                trandolapril, phenoxybenzamine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Exaggerated first dose hypotensive response.

              • verapamil

                phenoxybenzamine and verapamil both increase anti-hypertensive channel blocking. Use Caution/Monitor.

              • zotepine

                phenoxybenzamine and zotepine both increase anti-hypertensive channel blocking. Use Caution/Monitor.

              Minor (7)

              • brimonidine

                brimonidine increases effects of phenoxybenzamine by pharmacodynamic synergism. Minor/Significance Unknown.

              • butcher's broom

                phenoxybenzamine, butcher's broom. Either decreases effects of the other by Mechanism: pharmacodynamic antagonism. Minor/Significance Unknown.

              • ethanol

                phenoxybenzamine, ethanol. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypotension, esp. in Asian pts.

              • phenylephrine

                phenoxybenzamine, phenylephrine. Either decreases effects of the other by Mechanism: pharmacodynamic antagonism. Minor/Significance Unknown.

              • phenylephrine PO

                phenoxybenzamine, phenylephrine PO. Either decreases effects of the other by Mechanism: pharmacodynamic antagonism. Minor/Significance Unknown.

              • tizanidine

                tizanidine increases effects of phenoxybenzamine by pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypotension.

              • treprostinil

                treprostinil increases effects of phenoxybenzamine by pharmacodynamic synergism. Minor/Significance Unknown.

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              Adverse Effects

              Frequency Not Defined

              Orthostatic hypotension

              Tachycardia

              Dizziness

              Drowsiness

              Fatigue

              Malaise

              Sedation

              Dry mouth

              Nausea

              Vomiting

              Inhibition of ejaculation

              Miosis

              Nasal congestion

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              Warnings

              Contraindications

              Hypersensitivity to phenoxybenzamine

              Any conditions in which fall in BP is undesirable

              Orthostatic hypotension

              Cautions

              Cerebral or coronary arteriosclerosis, CHF, respiratory infection, renal impairment

              Concomitant use of drugs that stimulate alpha/beta receptors (may increase hypotension/tachycardia)

              May have carcinogenic potential

              Use caution in the elderly (increased risk of adverse effects)

              First dose effect may occur, causing a sudden and drastic fall in blood pressure after administering the first dose.

              Hypotension/syncope may occur with first few doses or with increase in dose

              Minimize by using small first dose at bedtime

              Increase dose slowly

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              Pregnancy & Lactation

              Pregnancy Category: C

              Lactation: Not known if excreted into breast milk, discontinue drug or do not nurse

              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.

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              Pharmacology

              Mechanism of Action

              Alpha blocker, noncompetitive alpha-adrenergic blockade of post ganglionic synapses in smooth muscle, exocrine glands

              Pharmacokinetics

              Half-Life: 24 hr

              Onset: Several hours

              Duration: ≥ 3 days

              Bioavailability: 20-30%

              Metabolism: Extensively metabolized in liver

              Metabolite: N-phenoxyisopropyl-benzylamine

              Excretion: Urine & feces

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              Images

              BRAND FORM. UNIT PRICE PILL IMAGE
              Dibenzyline oral
              -
              10 mg capsule
              phenoxybenzamine oral
              -
              10 mg capsule

              Copyright © 2010 First DataBank, Inc.

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              Patient Handout

              Patient Education
              phenoxybenzamine oral

              PHENOXYBENZAMINE - ORAL

              (fen-OX-ee-BEN-za-meen)

              COMMON BRAND NAME(S): Dibenzyline

              USES: This medication is used to treat high blood pressure and heavy sweating due to a certain tumor of the adrenal glands (pheochromocytoma). Phenoxybenzamine belongs to a class of drugs known as alpha blockers. It works by relaxing and widening blood vessels so that blood can flow more easily.

              HOW TO USE: Take this medication by mouth with or without food, usually 2 to 3 times daily or as directed by your doctor.The dosage is based on your medical condition and response to treatment.Use this medication regularly in order to get the most benefit from it. To help you remember, take it at the same times each day. Keep taking this medication even if you feel well. Most people with high blood pressure do not feel sick.Do not suddenly stop taking this medication without consulting your doctor. Your condition may become worse when the drug is suddenly stopped. Your dose may need to be gradually decreased.Tell your doctor if your condition worsens (for example, your routine blood pressure readings increase).

              SIDE EFFECTS: Stomach upset, nausea, stuffy nose, drowsiness, dizziness or decrease in pupil size may occur. If any of these effects persist or worsen, notify your doctor or pharmacist promptly.To lower your risk of dizziness and lightheadedness, get up slowly when rising from a sitting or lying position.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: fast heartbeat, fainting, sexual problems in males (such as trouble ejaculating), weakness.For males, in the very unlikely event that you have a painful or prolonged erection lasting 4 or more hours, stop using this drug and seek immediate medical attention, 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 phenoxybenzamine, tell your doctor or pharmacist if you are allergic to it; or to other alpha blockers (such as phentolamine); 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: blood vessel disease (such as cerebral arteriosclerosis, coronary artery disease), heart disease (such as heart failure), kidney disease, lung infections, certain eye problems (cataracts, glaucoma).This drug may make you dizzy or drowsy. Alcohol or marijuana (cannabis) can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).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. Dizziness 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.It is unknown if this drug 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 are: drugs to treat erectile dysfunction-ED or pulmonary hypertension (such as sildenafil, tadalafil), epinephrine, other alpha blockers (such as prazosin), other drugs for high blood pressure (such as diuretics, ACE inhibitors, beta blockers).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 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).

              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: fainting, severe weakness, fast heartbeat.

              NOTES: Do not share this medication with others.Have your blood pressure checked regularly while taking this medication. Learn how to monitor your own blood pressure at home, 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 August 2021. Copyright(c) 2021 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.

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              Tier Description
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              Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.