PRAZOSIN is an antihypertensive. Prazosin lowers, but does not cure, high blood pressure. It works by relaxing the blood vessels. Prazosin is sometimes used for prostate problems.

They need to know if you have any of the following conditions:

• angina
• kidney disease
• an unusual or allergic reaction to prazosin, other medicines, foods, dyes, or preservatives
• pregnant or trying to get pregnant
• breast-feeding

Take prazosin by mouth. Swallow the tablet with a drink of water. Taking the tablet with food can help to reduce side effects. Take your doses at regular intervals. Do not take your medicine more often than directed. Do not stop taking except on your prescriber's advice.

Contact your pediatrician or health care professional regarding the use of this medicine in children. Special care may be needed.

Overdosage: If you think you have taken too much of this medicine contact a poison control center or emergency room at once.

NOTE: This medicine is only for you. Do not share this medicine with others.

If you miss a dose, take it as soon as you can. If it is almost time for your next dose, take only that dose. Do not take double or extra doses.

Do not take prazosin if you are taking the following medications:

• other alpha-blockers such as alfuzosin, doxazosin, phentolamine, phenoxybenzamine, tamsulosin, terazosin

Prazosin may also interact with the following medications:

• medicines for colds and breathing difficulties
• medicines for high blood pressure
• monoamine oxidase inhibitors
• sildenafil (doses of sildenafil higher than 25 mg should be taken at least 4 hours apart from taking prazosin)
• tadalafil
• vardenafil
• water pills

Tell your prescriber or health care professional about all other medicines you are taking, including nonprescription medicines, nutritional supplements, or herbal products. Also tell your prescriber or health care professional if you are a frequent user of drinks with caffeine or alcohol, if you smoke, or if you use illegal drugs. These may affect the way your medicine works. Check with your prescriber or health care professional before stopping or starting any of your medicines.

Check your blood pressure regularly. Ask your prescriber or health care professional what your blood pressure should be and when you should contact him or her.

You may feel drowsy or dizzy. Do not drive, use machinery, or do anything that requires mental alertness until you know how prazosin affects you. To reduce the risk of dizzy or fainting spells, do not sit or stand up quickly. Avoid alcoholic drinks; they can make you more drowsy, and can increase flushing and rapid heartbeats. Taking initial doses of prazosin at bedtime can lessen the effects of drowsiness and dizziness, but be careful if you have to get up during the night. Drowsiness and dizziness are more likely to occur after the first dose, after an increase in dose, or during hot weather or exercise. These effects can decrease once your body adjusts to this medicine.

Although extremely rare in men taking prazosin, contact you health care provider immediately if you experience prolonged and painful erection of the penis which is unrelated to sexual activity (priapism). If not brought to immediate medical attention, priapism can lead to permanent erectile dysfunction (impotence).

Your mouth may get dry. Chewing sugarless gum or sucking hard candy, and drinking plenty of water, will help.

Do not take nonprescription medicine for weight-loss without asking your prescriber or health care professional. Also, do not take cough and cold, hay fever or sinus medications without asking your prescriber or health care professional.

If you are going to have surgery, tell your prescriber or health care professional that you are taking prazosin.

Side effects that you should report to your prescriber or health care professional as soon as possible:

• difficulty breathing, shortness of breath
• prolonged painful erection of the penis (priapism)
• blurred vision
• fainting spells, lightheadedness
• irregular heartbeat, palpitations or chest pain
• mental depression
• swelling of the legs and ankles
• vomiting

Side effects that usually do not require medical attention (report to your prescriber or health care professional if they continue or are bothersome):

• constipation or diarrhea
• drowsiness or dizziness
• dry mouth
• headache
• nausea
• sexual difficulties (impotence)
• stomach pain
• unusual weakness or tiredness

This list may not describe all possible side effects.

Keep out of the reach of children in a container that small children cannot open.

Store at room temperature between 15 and 30 degrees C (59 and 86 degrees F). Protect from light. Keep container tightly closed. Throw away any unused medicine after the expiration date.