This page contains brief details about the drug , it's indication, dosage & administaration, mechanism of action, related brands with strength, warnings and common side effects.

Background and Date of Approval

Phenoxybenzamine was initially approved by the United States Food and Drug Administration (FDA) on December 11, 1953. 

Mechanism of Action of undefined

Phenoxybenzamine works through non-selective alpha-adrenergic receptor blockade, inhibiting the action of neurotransmitters like norepinephrine on smooth muscle cells lining blood vessels, which leads to vasodilation, reduced vascular resistance, and consequent blood pressure reduction.

Uses of undefined

Phenoxybenzamine manages pheochromocytoma, a tumor that causes high blood pressure. It is also used as preoperative blood pressure stabilization before tumor removal.

undefined Drug administaration and Dosage available

Phenoxybenzamine can be administered orally in the form of capsules. It is usually taken by mouth with water. A healthcare professional provides the specific dosage and administration instructions based on the individual's condition and needs.

Warnings, Precautions and Side Effects of undefined


Phenoxybenzamine can cause dizziness and low blood pressure (hypotension). Orthostatic hypotension (sudden drop in blood pressure upon standing) can occur with this medication. It may lead to fluid retention, which can worsen heart failure symptoms.


Avoid activities that require alertness and coordination until you understand how Phenoxybenzamine affects you. Rise slowly from lying or sitting positions to prevent sudden drops in blood pressure and dizziness. If you have a history of heart failure, consult your healthcare provider before using this medication. Monitor for signs of fluid retention, such as swelling, and report any significant weight gain.

Side Effects

Phenoxybenzamine use may lead to various side effects, including dizziness, weakness, nausea, nasal congestion, headache, and palpitations due to its impact on blood pressure and smooth muscles. More serious effects encompass severe hypotension (low blood pressure), tachycardia (rapid heart rate), orthostatic hypotension, and fluid retention.

Word Of Advice

Inform your healthcare provider about your complete medical history, including any heart conditions, liver problems, kidney issues, lung disorders, and a history of low blood pressure before taking Phenoxybenzamine. Regularly monitor your blood pressure as directed by your healthcare provider. Be cautious when changing positions, especially from lying down to standing up, to avoid sudden drops in blood pressure and dizziness. Watch for signs of fluid retention, such as leg swelling or sudden weight gain, and inform your doctor if you notice any unusual changes. If you are scheduled for surgery, including dental procedures, inform your healthcare provider that you are taking this medication. Discuss dietary recommendations with your healthcare provider, especially regarding salt intake, as changes in blood pressure regulation could impact your dietary requirements. Be vigilant for signs of allergic reactions, such as rash, itching, swelling, or difficulty breathing. 

Frequently Asked Question


  1. Goodman & Gilman’s, The Pharmacological Basis of Therapeutics, Adrenergic agonists and antagonists, 12th edition, 2011, 309.
  2. KD Tripathi, Essentials of Medical Pharmacology, Antiadrenergic drugs and drugs for glaucoma, 7th edition, 2013, 141.
  3. ADVANZ Pharma, Electronic medicines compendium (emc), [Revised on 30th Aug 2022] [ Accessed on 24th August 2023],
  4. WellSpring Pharmaceutical Corporation, US Food and Drug Administration, [Revised on March 2008] [ Accessed on 24th August 2023],


The drug information on this page is not a substitute for medical advice, it is meant for educational purposes only. For further details, consult your doctor about your medical condition to know if you can receive this treatment.