Prazosin

Prazosin is used to treat high blood pressure (hypertension). Lowering blood pressure may reduce your risk of having a stroke or a heart attack.

Prazosin may also be used for other reasons not mentioned in this medication guide.

Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose. Use the medicine exactly as directed.

Prazosin lowers blood pressure and may cause dizziness or fainting, especially when you first start taking it or whenever your dose is changed. You may feel very dizzy when you first wake up.

Your blood pressure will need to be checked often.

Swallow the capsule whole and do not crush, chew, break, or open it.

Keep using this medicine as directed, even if you feel well. High blood pressure often has no symptoms. You may need to use blood pressure medication for the rest of your life.

Prazosin is only part of a complete treatment program that may also include diet, exercise, weight control, and special medical care. Follow your doctor's instructions very closely.

Some things can cause your blood pressure to get too low. This includes vomiting, diarrhea, or heavy sweating. Call your doctor if you are sick with vomiting or diarrhea.

Store at room temperature away from moisture and heat.

Follow all instructions on your medicine label and package. Inform each of your healthcare providers about all your medical conditions, allergies, and all medicines you are using.

You should not use prazosin if you are allergic to it.

Tell your doctor if you have ever had:

• low blood pressure, especially if it was caused by taking medications.

Prazosin can affect your pupils. If you are having cataract surgery, inform your surgeon ahead of time that you use prazosin.

Tell your doctor if you are pregnant or plan to become pregnant. It is not known if prazosin will harm an unborn baby. However, having high blood pressure during pregnancy may lead to complications such as diabetes or eclampsia (dangerously high blood pressure that can cause medical problems for both mother and baby). The benefit of treating high blood pressure may outweigh any risks to the baby.

It may not be safe to breastfeed while using this medicine. Ask your doctor about any risks.

Prazosin is not approved for use by anyone younger than 18 years old.

Get emergency medical help if you have signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Prazosin may cause serious side effects. Call your doctor right away if you have:

• a light-headed feeling, like you might pass out;
• pounding heartbeats or fluttering in your chest;
• new or worsening chest pain; or
• upper stomach pain, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).

Call your doctor or seek emergency medical attention if your erection is painful or lasts longer than 4 hours. A prolonged erection (priapism) can damage the penis.

Common side effects of prazosin may include:

• dizziness, drowsiness;
• headache;
• feeling weak or tired; or
• nausea.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Usual Adult Dose for Hypertension:

Initial dose: 1 mg orally 2 or 3 times a dayMaintenance dose: 1 to 20 mg orally per day in divided dosesComments:-Titrate slowly as determined by blood pressure response.-Therapeutic dosages usually range from 6 to 15 mg per day in divided doses.-Total daily doses greater than 20 mg usually do not increase efficacy, but some patients may benefit from daily doses up to 40 mg per day in divided doses.

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include extreme drowsiness or slow reflexes.

Avoid driving or doing anything dangerous until you know how prazosin will affect you. Your reactions could be impaired.

Avoid getting up too quickly from a sitting or lying position, or you may feel dizzy.

Drinking alcohol with this medicine can cause side effects.

Tell your doctor about all your other medicines, especially:

• propranolol;
• any other blood pressure medication;
• a diuretic or "water pill"; or
• sildenafil (Viagra) and other erectile dysfunction medicines.

This list does not cover everything. Other drugs may affect prazosin, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are included here.