Prazosin

Prazosin treats high blood pressure. Can cause a low blood pressure when you stand up from sitting or lying down, so get up slowly. Slowly sit up before standing.

Prazosin Overview

Reviewed: July 9, 2013
Updated: 

Prazosin is a prescription medication used to treat high blood pressure. Prazosin belongs to a group of drugs called alpha-blockers. It lowers blood pressure by relaxing veins and arteries so that blood can more easily pass through them.

This medication comes in capsule form and is usually taken 2 or 3 times a day.

Common side effects include dizziness, headache, and weakness. Prazosin can cause drowsiness. Do not drive or operate heavy machinery until you know how it will affect you.

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Prazosin Cautionary Labels

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Uses of Prazosin

Prazosin is a prescription medication used to treat high blood pressure.

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.

Prazosin Brand Names

Prazosin may be found in some form under the following brand names:

Prazosin Drug Class

Prazosin is part of the drug class:

Side Effects of Prazosin

Serious side effects have been reported. See "Drug Precautions" section.

Common side effects include:

  • dizziness
  • headache
  • drowsiness
  • lack of energy
  • weakness
  • palpitations
  • nausea

This is not a complete list of prazosin side effects. Ask your doctor or pharmacist for more information.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

 

Prazosin Interactions

Tell your doctor about all the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements. Especially tell your doctor if you take:

  • avanafil (Stendra)
  • sildenafil (Viagra, Revatio)
  • tadalafil (Cialis, Adcirca)
  • vardenafil (Levitra, Staxyn)
  • verapamil (Calan, Covera, Isoptin, Verelan)

This is not a complete list of prazosin drug interactions. Ask your doctor or pharmacist for more information.

Prazosin Precautions

Serious side effects have been reported including:

  • Extremely rarely, prazosin and similar medications have caused painful erection of the penis, sustained for hours and unrelieved by sexual intercourse or masturbation. This condition, known medically as priapism, is serious, and if untreated it can be followed by permanent inability to have an erection. If you have a prolonged abnormal erection, call your doctor or go to an emergency room as soon as possible.
  • Tell your surgeon if you take or have taken prazosin and plan to have surgery for cataracts (clouding of the eye). During cataract surgery, a condition called Intraoperative Floppy Iris Syndrome (IFIS) can happen if you take or have taken prazosin.
  • Prazosin lowers blood pressure and may cause dizziness or fainting, especially when you first start taking it, or when you start taking it again. Call your doctor if you have severe dizziness or feel like you might pass out.

Prazosin can cause drowsiness. Do not drive or operate heavy machinery until you know how prazosin affects you.

Do not take prazosin if you:

  • are allergic to prazosin or any inactive ingredient in prazosin
  • are allergic to any of the medications related to prazosin such as alfuzosin (Uroxatral), doxazosin (Cardura), and terazosin (Hytrin)

Prazosin Food Interactions

Medicines can interact with certain foods. In some cases, this may be harmful and your doctor may advise you to avoid certain foods. In the case of prazosin there are no specific foods that you must exclude from your diet when receiving this medication.

 

 

Inform MD

Before taking prazosin, tell your doctor about all of your medical conditions. Especially tell your doctor if you:

  • are allergic to prazosin or any of its inactive ingredients 
  • have or have ever had prostate cancer
  • have or have ever had liver disease
  • have narcolepsy
  • are pregnant or breastfeeding

Tell your doctor about all the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements.

Prazosin and Pregnancy

Tell your doctor if you are pregnant or plan to become pregnant.

The FDA categorizes medications based on safety for use during pregnancy. Five categories - A, B, C, D, and X, are used to classify the possible risks to an unborn baby when a medication is taken during pregnancy.

Prazosin falls into category C. There are no good studies in pregnant women. Prazosin should be used during pregnancy only if the possible benefit outweighs the possible risk to the unborn baby.

 

 

Prazosin and Lactation

Tell your doctor if you are breastfeeding or plan to breastfeed.

Prazosin has been detected in human breast milk. Because of the possibility for adverse reactions in nursing infants from prazosin, a choice should be made whether to stop nursing or to stop use of prazosin. Determining the importance of the drug to the mother should be considered.

Prazosin Usage

  • Take prazosin exactly as prescribed.
  • Prazosin is usually taken 2 or 3 times a day, at regular intervals. 
  • This medication can be taken with or without food.
  • If you miss a dose, take the missed dose as soon as you remember. If it is almost time for the next dose, skip the missed dose and take your next dose at the regular time. Do not take two doses of prazosin at the same time.

Prazosin Dosage

Take prazosin exactly as prescribed. Follow the directions on your prescription label carefully. Your doctor will likely start you on a low dose and gradually increase the dose as necessary.

The recommended starting prazosin dose is 1 mg two or three times a day. Your doctor may gradually increase your dose until your maintenance dose is reached.

Daily doses commonly range between 6 mg and 15 mg.

Prazosin Overdose

If you take too much prazosin, call your local Poison Control Center or seek emergency medical attention right away.

Other Requirements

  • Store at room temperature below 86°F (30°C).
  • Keep this and all medications out of the reach of children.