Generic Name: prazosin, Oral capsule

Generic Name:

prazosin, Oral capsule

Minipress

All Brands

  • Minipress
SECTION 1 of 5

Highlights for prazosin

Oral capsule
1

Prazosin is used to treat high blood pressure (hypertension). It can be used alone or in combination with other medications to help lower your blood pressure.

2

The typical dose is 1 mg, taken two or three times per day. If your blood pressure is still high, your doctor can then increase your dose. The 2-mg and 5-mg capsules won’t be used for your starting dose.

3

The most common side effects of prazosin include dizziness, headache, drowsiness, lack of energy, weakness, heart palpitations, and nausea.

4

Dizziness and drowsiness may occur after your first dose of prazosin. Avoid driving or performing any hazardous tasks for the first 24 hours after taking this medicine or when your dose is increased.

5

Dizziness, lightheadedness, and even fainting can also occur if you stand up quickly from a lying or sitting position (orthostatic hypotension). Getting up slowly may help lessen this problem. These effects may also occur if you drink alcohol, stand for long periods, exercise, or if the weather is hot.

IMPORTANT INFORMATION

Loss of consciousness

Because this medication lowers your blood pressure, prazosin may cause you to pass out, faint, or suddenly lose consciousness. This can happen within 30 to 90 minutes of your first dose of prazosin. It can also happen if your prazosin dose is increased too quickly, or if you’re already on a high dose of prazosin and you’re started on another blood pressure medication.

Prolonged erections

Prazosin may cause prolonged erections (known as priapism). If you have an erection that lasts more than 4 hours, call your doctor or seek emergency medical help right away. If this isn’t treated, it may result in erectile dysfunction or tissue scarring.

Intraoperative floppy iris syndrome

If you have cataracts and need surgery, be aware that prazosin may increase your risk for complications during surgery known as Intraoperative Floppy Iris Syndrome (IFIS). If you need eye surgery, let your eye doctor know that you’re taking prazosin. The doctor may give you medications before surgery or perform the surgery using different techniques to help decrease your risk for IFIS.

Drug Features

Prazosin is a prescription drug. It’s available as an oral capsule.

Prazosin is available in a generic version. Generic drugs usually cost less. In some cases they may not be available in every strength or form as the brand. Talk to your healthcare provider to see if the generic will work for you.

This drug may be used as part of a combination therapy. That means you need to take it with other drugs.

Why It's Used

Prazosin is used to lower your blood pressure. If your blood pressure stays too high, it can put you at risk for serious health problems such as heart attack and stroke.

How It Works

Your blood pressure can increase when your blood vessels constrict and get narrower. Prazosin works by relaxing your blood vessels so that blood will flow more easily through them. This will then make your blood pressure decrease.

SECTION 2 of 5

prazosin Side Effects

Oral capsule

Most Common Side Effects

The most common side effects of prazosin include:

  • dizziness

  • drowsiness

  • lightheadedness

  • headache

  • lack of energy

  • weakness

  • palpitations (feel like your heart is racing or fluttering)

  • nausea

If these effects are mild, they may disappear within a few days or a couple of weeks. If they’re more severe or don’t disappear, talk to your doctor or pharmacist.

Serious Side Effects

If you experience any of these serious side effects, call your doctor right away. If your symptoms are potentially life threatening, or if you think you’re experiencing a medical emergency, call 9-1-1.

  • loss of consciousness (this can occur if you stand up too quickly from a lying or sitting position)

  • an erection lasting more than 4 hours

  • very fast heartbeat

  • swelling of your hands and feet

  • difficulty breathing

  • depression

  • allergic reactions, including:

    • skin rash
    • hives
    • swelling of the lips, face, or tongue
    • trouble breathing
Pharmacist's Advice
Healthline Pharmacist Editorial Team

Dizziness and drowsiness may occur after your first dose of prazosin. Avoid driving or performing any hazardous tasks for the first 24 hours after taking this medicine or when your dose is increased.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this information includes all possible side effects. This information is not a substitute for medical advice. Always discuss possible side effects with a healthcare provider who knows your medical history.
SECTION 3 of 5

prazosin May Interact with Other Medications

Oral capsule

Prazosin can interact with other medications, herbs, or vitamins you might be taking. That’s why your doctor should manage all of your medications carefully. If you’re curious about how this drug might interact with something else you’re taking, talk to your doctor or pharmacist.

Note: You can reduce your chances of drug interactions by having all of your prescriptions filled at the same pharmacy. That way, a pharmacist can check for possible drug interaction.

Alcohol Interaction

If you drink alcohol while on prazosin, you may experience dizziness, lightheadedness, and fainting.

Medications That Might Interact with This Drug

Other blood pressure drugs
  • metoprolol
  • atenolol
  • carvedilol
  • lisinopril
  • losartan
  • valsartan
  • hydrochlorothiazide
  • amlodipine
  • clonidine

If you take prazosin together with these drugs, they will decrease your blood pressure even more and may drop it to a dangerously low level. Your doctor can help you avoid this by reducing your prazosin dose, adding any other blood pressure medications carefully, and then increasing your prazosin slowly depending on how you’re responding and tolerating these medications. Your doctor may also have you check your blood pressure more often.

Erectile dysfunction drugs
  • avanafil
  • sildenafil
  • tadalafil
  • vardenafil

These drugs can all lower your blood pressure. Taking any of these drugs with prazosin will lower your blood pressure even more and may drop it to a dangerously low level. Your doctor may choose to adjust your doses or choose to not start you at all on this combination of drugs.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs interact differently in each person, we cannot guarantee that this information includes all possible interactions. This information is not a substitute for medical advice. Always speak with your healthcare provider about possible interactions with all prescription drugs, vitamins, herbs and supplements, and over-the-counter drugs that you are taking.

People with heart problems

Use prazosin with caution if you have heart failure, swelling of your hands and feet (edema), tendency to get very dizzy or lightheaded when you stand from a lying or sitting position (orthostatic hypotension), or a type of chest pain called angina. Prazosin may worsen these conditions.

People with eye problems

Prazosin can cause blurry vision and eye pain. If you already have eye problems such as cataracts and need surgery, prazosin may increase your risk for serious complications during eye surgery.

Pregnant women

Prazosin is a category C pregnancy drug. That means two things:

  1. Research in animals has shown harmful effects to the fetus when the mother takes the drug.
  2. There haven’t been enough studies done in humans to be certain how the drug might affect the fetus.

Speak with your doctor if you’re pregnant or planning to become pregnant. Prazosin should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Women who are breast-feeding

Prazosin passes through breast milk. Talk to your doctor before breastfeeding while taking prazosin.

For seniors

If you’re 65 years or older and you take prazosin, you’re at an increased risk for a sudden drop in blood pressure when you stand up from a lying or sitting position (orthostatic hypotension). This can cause dizziness and lightheadedness. Your doctor may start you on a lower dose, monitor your blood pressure more closely, or choose a safer blood pressure drug instead.

For children

Safety and effectiveness in children haven’t been established.

Special Kid Safety: Keep prazosin out of the reach of children.

Allergies

Prazosin may cause a severe allergic reaction. Symptoms may include:

  • skin rash
  • hives
  • swelling of the lips, face, or tongue
  • trouble breathing

If these symptoms occur, you should seek immediate emergency help.

Don’t take this drug again if you’ve ever had an allergic reaction to it. Taking it again could be fatal.

SECTION 4 of 5

How to Take prazosin (Dosage)

Oral capsule

All possible dosages and forms may not be included here. Your dose, form, and how often you take it will depend on:

  • your age
  • the condition being treated
  • how severe your condition is
  • other medical conditions you have
  • how you react to the first dose

What Are You Taking This Medication For?

High blood pressure (hypertension)
Form: Oral capsule
Strengths: 1 mg, 2 mg, and 5 mg
Adult Dosage (ages 18 years and older)
  • 1 mg, taken either two or three times per day as instructed by your doctor
  • Your doctor may slowly increase your dose up to a maximum of 20 mg per day taken in evenly divided doses.
  • Most people will need a dose ranging from 6 mg to 15 mg daily, taken in evenly divided doses.
Child Dosage (ages 0-17 years)

Dosage for people younger than 18 years old hasn’t been established.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this list includes all possible dosages. This information is not a substitute for medical advice. Always to speak with your doctor or pharmacist about dosages that are right for you.
Pharmacist's Advice
Healthline Pharmacist Editorial Team

Prazosin comes with serious risks if you don't take it as prescribed.

If You Don’t Take It at All

If you don’t take your prazosin and your blood pressure stays too high, it can put you at risk for serious health problems such as heart attack and stroke.

If You Don’t Take It on Schedule

If you don’t take it on schedule, the drug will be less effective at maintaining a healthy blood pressure, which could put you at a higher risk for heart attack and stroke.

If You Take Too Much

If you take too much prazosin, you may experience a huge drop in blood pressure, leading to extreme dizziness, lightheadedness, fainting, or even loss of consciousness and shock. If you think you may have taken too much prazosin, call your doctor or get emergency medical help right away.

What to Do If You Miss a Dose

If you forget to take your dose, take it as soon as you remember, unless you remember just a few hours before the time for your next dose. Then only take one dose.

Never try to catch up by taking two tablets at once. This could result in toxic side effects, such as a huge drop in blood pressure (which can lead to dizziness, lightheadedness, fainting, or even loss of consciousness).

How to Tell If the Drug Is Working

Your blood pressure will decrease.

Prazosin is a long-term drug treatment.

Important Considerations for Taking Prazosin
can be opened These are capsules, which may be opened if needed
storage Store it at room temperature See Details
refillable Prescription is refillable
travel Travel See Details
self-management Self-Management See Details
clinical monitoring Clinical Monitoring See Details
usually stocked Generic prazosin is usually stocked at pharmacies

Store it at room temperature

Keep it from 68–77°F (20–25ºC).

Protect it from light and moisture.

Keep your drugs away from areas where they could get wet, such as bathrooms. Store these drugs away from moisture and damp locations.

Travel

When traveling with your medication:

  • Always carry your medication with you or in your carry-on bag.
  • Don’t worry about airport X-ray machines; they can’t hurt your medication.
  • You may need to produce your pharmacy’s preprinted label clearly identifying the medication. Keep the original pharmacy prescription-labeled box when traveling with your medication.

Self-Management

Your doctor may recommend that you check and record your blood pressure daily.

If your doctor instructs you to monitor and record your blood pressure daily, then a home blood pressure monitor will be needed.

Clinical Monitoring

Your doctor will regularly check the following to make sure this medication is working and is safe for you:

  • blood pressure
  • heart rate (prazosin can cause a fast heart rate known as tachycardia)

Are There Any Alternatives?

There are several medications in this class and other classes that can be used to treat high blood pressure. Some may be more suitable for you than others. Talk to your doctor about possible alternatives.

What does the pill look like?

Showing - out of 21
SECTION 5 of 5

How Much Does prazosin Cost?

Oral capsule
We've partnered with GoodRX so you can compare prices and save money on your next prescription. Check out the lowest cash prices below and enter your zip code to find the best deal near you.

Compare prices and save money on your next refill!

Lowest price for prazosin

Walmart $8.05
Sams Club $8.05
Target $9.71
These represent the lowest cash prices for prazosin and may be lower than your insurance.

Find the lowest prices of prazosin near you

These represent the lowest cash prices for prazosin and may be lower than your insurance.

Show Sources

Content developed in collaboration with University of Illinois-Chicago, Drug Information Group

Medically reviewed by Creighton University, Center for Drug Information and Evidence-Based Practice on July 20, 2015

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up-to-date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.

Read This Next

Lower Your Blood Pressure Fast With These Tips
Lower Your Blood Pressure Fast With These Tips
The Health Potential of Yucca
The Health Potential of Yucca
Black Pepper: The King of Spices
Black Pepper: The King of Spices
Advertisement
Advertisement
Advertisement