What is doxazosin mesylate, and how does it work (mechanism of action)?

Doxazosin is an oral drug used for treating high blood pressure and symptoms of benign prostatic hyperplasia (BPH, a noncancerous enlargement of the prostate gland). It belongs to a class of drugs called alpha-1 adrenergic blockers. Other drugs in this class include alfuzosin (Uroxatral), terazosin (Hytrin), tamsulosin (Flomax), silodosin (Rapaflo), and prazosin (Minipress). Doxazosin prevents norepinephrine that is released by nerves from binding to alpha-1 receptors on smooth muscle surrounding blood vessels and in the prostate and bladder. By blocking the effect of norepinephrine, doxazosin relaxes the smooth muscle. Relaxation of the smooth muscle surrounding blood vessels causes them to enlarge (dilate) and thereby reduces blood pressure. Relaxation of smooth muscle in the prostate and bladder improves the flow of urine and reduces the pain and discomfort characteristic of BPH. The FDA approved doxazosin in November 1990.

What brand names are available for doxazosin mesylate?

Cardura, Cardura XL

Is doxazosin mesylate available as a generic drug?


Do I need a prescription for doxazosin mesylate?


What are the side effects of doxazosin mesylate?

Common side effects of doxazosin include:

Doxazosin causes significant reduction in blood pressure after administration of the first dose (first dose effect). This reduction in blood pressure may be associated with dizziness and fainting, especially when rising from a sitting position. To avoid this, patients should rise slowly from a sitting position, start treatment with the 1 mg dose, and then doses should be adjusted upwards slowly. Priapism (painful, prolonged penile erection) and a reduction in white blood cells have been associated with doxazosin.

MORE SERIOUS : Doxazosin can cause intraoperative floppy iris syndrome (IFIS) during cataract surgery. Patients should inform their eye surgeon that they are taking doxazosin.

Which drugs or supplements interact with doxazosin mesylate?

Vardenafil (Levitra) or tadalafil (Cialis) and doxazosin have additive blood pressure lowering effects. Combining vardenafil or tadalafil (Cialis) with doxazosin may cause excessive blood pressure reduction.

How to Lower Blood Pressure: Exercise Tips

Is doxazosin mesylate safe to take if I’m pregnant or breastfeeding?

There are no adequate studies of doxazosin in pregnant women.

There are no adequate studies of doxazosin in nursing mothers.

What else should I know about doxazosin mesylate?

What preparations of doxazosin mesylate are available?

Tablets: 1, 2, 4, and 8 mg. Tablets (Extended Release): 4, 8 mg

How should I keep doxazosin mesylate stored?

Doxazosin should be stored at room temperature, 15 C – 30 C (59 F – 86 F).

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Medically Reviewed on 12/10/2018


Medically reviewed by John P. Cunha, DO, FACOEP; Board Certified Emergency Medicine


FDA Prescribing Information