What Is Phenoxybenzamine? Uses, Dosage, and What You Need to Know in 2026

Phenoxybenzamine (brand name Dibenzyline) is a prescription medication used to control dangerously high blood pressure and excessive sweating caused by pheochromocytoma — a rare tumor of the adrenal gland. It belongs to a class of drugs called alpha-adrenergic blockers, and it works by blocking specific receptors in blood vessels and other tissues that respond to adrenaline and noradrenaline.

This guide covers everything you need to know about phenoxybenzamine — what it treats, how to take it, what makes it unique among alpha-blockers, and what patients frequently ask about it.

What Is Phenoxybenzamine Used For?

Phenoxybenzamine has one FDA-approved indication:

Pheochromocytoma: Management of episodes of hypertension and sweating. In practice, this means it is almost always used to prepare patients for surgical removal of the pheochromocytoma tumor.

Pheochromocytoma is a rare tumor, usually benign, that grows in the adrenal gland (located above the kidneys). It secretes excess catecholamines — primarily epinephrine (adrenaline) and norepinephrine (noradrenaline) — which cause paroxysmal (episodic) severe hypertension, pounding headaches, profuse sweating, and rapid heart rate. Without treatment, these surges can cause stroke, heart attack, or cardiac arrhythmia.

Off-Label Uses

Physicians sometimes prescribe phenoxybenzamine off-label for:

Neurogenic bladder and urinary retention (relaxes smooth muscle of the urethra)

Partial prostatic obstruction (BPH-related outlet obstruction)

Carcinoid tumor (serotonin-secreting tumors, leveraging phenoxybenzamine's 5-HT2A receptor antagonism)

What Drug Class Is Phenoxybenzamine?

Phenoxybenzamine is a non-selective, irreversible alpha-adrenergic blocker. Here is what that means:

Non-selective: It blocks both alpha-1 and alpha-2 adrenergic receptors, unlike newer selective agents (like doxazosin) that target only alpha-1.

Irreversible: Phenoxybenzamine forms a permanent covalent bond with alpha receptors. Unlike most drugs, it cannot be displaced by the natural binding molecule (adrenaline). The blockade only ends when the body makes new receptors — a process that takes about 24 hours or longer.

What Does Phenoxybenzamine Look Like?

Phenoxybenzamine hydrochloride is available as 10 mg oral capsules. The brand Dibenzyline comes in a red capsule imprinted "WPC 001" and "10 mg." The generic form appears similar. It is taken by mouth, typically 2 to 3 times a day, with the dose gradually increased over days to weeks under physician supervision.

How Is Phenoxybenzamine Dosed?

Dosing is individualized and titrated carefully:

Starting dose: 10 mg twice daily

Titration: Increased by 10-20 mg every 2-3 days as tolerated

Usual maintenance: 20-40 mg two or three times daily (total 40-120 mg/day for most patients)

Preoperative timeline: Most patients are ready for surgery within 7-14 days after starting, though some centers use 2-4 weeks

Blood pressure goals during preparation:

Seated blood pressure: below 120/80 mmHg

Standing systolic blood pressure: above 90 mmHg (to avoid excessive orthostatic hypotension)

Is Phenoxybenzamine a Controlled Substance?

No. Phenoxybenzamine is not a controlled substance under the DEA Controlled Substances Act. It has no Schedule designation. Unlike ADHD medications or opioids, it does not require special paper prescriptions, triplicate forms, or DEA number verification at the pharmacy.

How Much Does Phenoxybenzamine Cost?

Despite being a generic medication, phenoxybenzamine carries a high price tag because of the small market. Retail prices typically exceed $6,700 for 60 capsules (a 30-day supply) without insurance or coupons. With a GoodRx coupon, the price drops to approximately $598 at participating pharmacies. Insurance coverage with prior authorization can bring the cost down further.

For a full breakdown of savings options, see: How to Save Money on Phenoxybenzamine in 2026: Coupons, Discounts, and Patient Assistance.

And because most pharmacies do not stock phenoxybenzamine, you may need help finding a pharmacy that carries it. medfinder calls pharmacies near you to check availability and texts you the results.