Prazosin is in a group of drugs called alpha-adrenergic (AL-fa ad-ren-ER-jik) blockers. Prazosin relaxes your veins and arteries so that blood can more easily pass through them.

Prazosin is used to treat hypertension (high blood pressure).

Prazosin may also be used for other purposes not listed in this medication guide.

You should not use this medication if you are allergic to prazosin or similar medicines such as alfuzosin (Uroxatral), doxazosin (Cardura), silodosin (Rapaflo), tamsulosin (Flomax), or terazosin (Hytrin).

Prazosin may cause dizziness or fainting, especially when you first start taking it or whenever your dose is changed. Be careful if you drive or do anything that requires you to be alert. Avoid standing for long periods of time or becoming overheated during exercise and in hot weather. Avoid getting up too fast from a sitting or lying position, or you may feel dizzy.

Prazosin can affect your pupils during cataract surgery. Tell your eye surgeon ahead of time that you are using this medication. Do not stop using prazosin before surgery unless your surgeon tells you to.

Tell your doctor about all other medications you use, especially other blood pressure medications including diuretics (water pills).

You should not use this medication if you are allergic to prazosin or similar medicines such as alfuzosin (Uroxatral), doxazosin (Cardura), silodosin (Rapaflo), tamsulosin (Flomax), or terazosin (Hytrin).

Prazosin can affect your pupils during cataract surgery. Tell your eye surgeon ahead of time that you are using this medication. Do not stop using prazosin before surgery unless your surgeon tells you to.

FDA pregnancy category C. It is not known whether prazosin will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using this medication.

Prazosin can pass into breast milk and may harm a nursing baby. Do not use this medication without telling your doctor if you are breast-feeding a baby.