Treating high blood pressure and benign prostatic hyperplasia (BPH). It may also be used to treat other conditions as determined by your doctor.

Prazosin is an alpha-blocker. The exact way it works is unknown, but it is thought to block a chemical in the body, causing blood vessels and the muscles around the urethra to relax. This helps to lower blood pressure and to improve urinary symptoms associated with enlargement of the prostate (BPH).

Do NOT use Prazosin if:

• you are allergic to any ingredient in Prazosin
• you are taking phosphodiesterase type 5 inhibitors (eg, vardenafil, tadalafil) or modafinil

Contact your doctor or health care provider right away if any of these apply to you.

Before using Prazosin :

Some medical conditions may interact with Prazosin. Tell your doctor or pharmacist if you have any medical conditions, especially if any of the following apply to you:

• if you are pregnant, planning to become pregnant, or are breast-feeding
• if you are taking any prescription or nonprescription medicine, herbal preparation, or dietary supplement
• if you have allergies to medicines, foods, or other substances
• if you have chest pain, heart disease, narcolepsy, or kidney problems

Some MEDICINES MAY INTERACT with Prazosin. Tell your health care provider if you are taking any other medicines, especially any of the following:

• Indomethacin because the effectiveness of Prazosin may be decreased
• Verapamil because the actions and side effects of Prazosin may be increased
• Beta-blockers (eg, propranolol), bupivacaine, nifedipine, or phosphodiesterase type 5 inhibitors (eg, sildenafil) because the actions and side effects of these medicines may be increased
• Modafinil because its effectiveness may be decreased by Prazosin

This may not be a complete list of all interactions that may occur. Ask your health care provider if Prazosin may interact with other medicines that you take. Check with your health care provider before you start, stop, or change the dose of any medicine.

How to use Prazosin :

Use Prazosin as directed by your doctor. Check the label on the medicine for exact dosing instructions.

• Prazosin may be taken with or without food.
• If you miss a dose of Prazosin , take it as soon as possible. If it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not take 2 doses at once.

Ask your health care provider any questions you may have about how to use Prazosin.

Important safety information:

• Prazosin may cause dizziness, lightheadedness, or fainting after the first dose. Take the first dose at bedtime. If you get up during the night, sit up and stand slowly. Continue to sit up and stand slowly while you are taking Prazosin.
• Prazosin may cause dizziness, drowsiness, lightheadedness, or blurred vision. Do not drive, operate machinery, or do anything else that could be dangerous until you know how you react to Prazosin. Using Prazosin alone, with certain other medicines, or with alcohol may lessen your ability to drive or to perform other potentially dangerous tasks.
• Before drinking alcohol, discuss it with your doctor.
• Patients being treated for high blood pressure often feel tired and run down for a few weeks after beginning therapy. Continue taking your medicine even though you may not feel quite "normal."
• Avoid engaging in any hazardous tasks for at least 24 hours after taking the first dose, missing several doses, increasing the dose, or taking other high blood pressure medications.
• Drinking alcohol, standing for long periods of time, exercising, and exposing yourself to hot weather can cause dizziness, lightheadedness, or fainting while you are taking Prazosin.
• Use Prazosin with extreme caution in the ELDERLY because they may be more sensitive to its effects.
• Prazosin is not recommended for use in CHILDREN; safety and effectiveness have not been confirmed.
• PREGNANCY and BREAST-FEEDING: If you become pregnant, discuss with your doctor the benefits and risks of using Prazosin during pregnancy. This medicine is excreted in breast milk. If you are or will be breast-feeding, check with your doctor to discuss the risks to your baby.

Possible side effects of Prazosin :

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome:

Constipation; depression; dizziness; drowsiness; dry mouth; feeling of a whirling motion; flushing; frequent urination; headache; lack of energy; lightheadedness; nasal congestion; nausea; nervousness; nosebleed; stuffy nose; swelling; vomiting; weakness.

Seek medical attention right away if any of these SEVERE side effects occur:

Severe allergic reactions (rash; hives; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); blurred vision; fainting; pounding heartbeat; puffiness in hands or feet; rapid heartbeat.