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What is the most important information I should know about prazosin?

To avoid falling, take the first dose at bedtime. Prazosin may cause dizziness. It is a good idea to take every dose at bedtime, if possible.

Use caution when you stand or sit up from a lying position, especially if you wake up during the night. Dizziness may occur when changing positions.

Do not stop taking this drug suddenly even if you feel better. Stopping suddenly could cause your blood pressure to increase.

Warning

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

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What is prazosin?

Prazosin is in a class of drugs called alpha-adrenergic blockers. Prazosin causes the blood vessels (veins and arteries) to relax and expand, which allows blood to pass more easily through them.

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

Prazosin may be used for purposes other than those listed in this medication guide.


Precautions

Before taking this medication, tell your doctor if you have any type of kidney or liver disease. You may need a dosage adjustment or special monitoring during therapy with prazosin.

Prazosin is in the FDA pregnancy category C. This means that it is not known whether prazosin will harm an unborn baby. Do not take prazosin without first talking to your doctor if you are pregnant.

Prazosin passes into breast milk and may affect a nursing baby. Do not take prazosin without first talking to your doctor if you are breast-feeding a baby.

Avoid alcohol while taking prazosin. Alcohol may cause drowsiness or severely low blood pressure while taking prazosin.

Use caution when driving, operating machinery, or performing other hazardous activities until you know how the medication affects you. Prazosin may cause dizziness or drowsiness. If you experience dizziness or drowsiness, avoid these activities.

Avoid becoming overheated. Low blood pressure, dizziness, and fainting could result. Be careful not to overexert yourself, and use caution in hot weather.

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Instructions

Seek emergency medical attention.

Symptoms of a prazosin overdose include weakness, dizziness, and fainting; a weak, fast pulse; cold, clammy skin; and possibly loss of consciousness or coma.

Take the missed dose as soon as you remember. However, if it is almost time for the next dose, skip the dose you missed and take only the next regularly scheduled dose. Do not take a double dose of this medication. A double dose could cause your blood pressure to become severely low.

If you miss doses for several days in a row, call your doctor before taking any additional doses. You may need to restart treatment with a lower dose.

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Side-effects

If you experience any of the following serious side effects, stop taking prazosin and seek emergency medical attention or contact your doctor immediately:

  • an allergic reaction (difficulty breathing; closing of your throat; swelling of your lips, tongue, or face; or hives);
  • an increased heartbeat;
  • shortness of breath or chest pain; or
  • a rash.

Other, less serious side effects may be more likely to occur. Continue to take prazosin and talk to your doctor if you experience

  • vivid dreams;
  • dizziness or drowsiness;
  • weakness, fatigue, or ill feeling;
  • nausea, vomiting, diarrhea, constipation, abdominal pain, or decreased appetite;
  • fluid retention or slight weight gain;
  • joint or muscle aches;
  • headache, irritability, or depression;
  • increased urination;
  • decreased sex drive; or
  • numbness or tingling in your hands, feet, arms, or legs.

Side effects other than those listed here may also occur. Talk to your doctor about any side effect that seems unusual or that is especially bothersome.

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Interactions

Talk to your doctor and pharmacist before taking any prescription or over-the-counter medicines, including herbal supplements, during treatment with prazosin.

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Disclaimer

Every effort has been made to ensure that the information provided by Cerner Multum, Inc. ('Multum') is accurate, up-to-date, and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. Multum information has been compiled for use by healthcare practitioners and consumers in the United States and therefore Multum does not warrant that uses outside of the United States are appropriate, unless specifically indicated otherwise. Multum's drug information does not endorse drugs, diagnose patients or recommend therapy. Multum's drug information is an informational resource designed to assist licensed healthcare practitioners in caring for their patients and/or to serve consumers viewing this service as a supplement to, and not a substitute for, the expertise, skill, knowledge and judgment of healthcare practitioners. The absence of a warning for a given drug or drug combination in no way should be construed to indicate that the drug or drug combination is safe, effective or appropriate for any given patient. Multum does not assume any responsibility for any aspect of healthcare administered with the aid of information Multum provides. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the drugs you are taking, check with your doctor, nurse or pharmacist.

Copyright 1996-2004 Cerner Multum, Inc. Version 2.05. Revision date 8/23/04

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