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

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.