Prazosin Dosages for Adults: Your GoodRx Guide

Prazosin (Minipress) is an alpha blocker medication used to treat high blood pressure. It works by relaxing your blood vessels. You may be prescribed prazosin on its own, or in combination with other medications to lower your blood pressure. It may also be used off-label to treat sleep issues related to post-traumatic stress disorder (PTSD), like nightmares. Prazosin is available as a capsule that you typically take by mouth 2 to 3 times per day. 

In this guide, we’ll discuss the typical prazosin dosages, dosage adjustments, and more. Your healthcare provider or pharmacist can answer questions you have about your prazosin dosage, which may be different than what’s covered below.

What’s the typical prazosin dosage for adults?

Prazosin is an oral medication used to treat high blood pressure. It comes as 1 mg, 2 mg, and 5 mg capsules. Depending on your prescribed dosage, you may need to take more than one capsule at a time. 

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You can take your prazosin dose with or without food. But if it makes you feel nauseated, try taking it with food to see if that helps.

High blood pressure

For high blood pressure, the typical starting prazosin dosage is 1 mg by mouth 2 to 3 times a day. Your dosage may be slowly increased up to 20 mg daily, taken in divided doses. Typically, the usual total daily dosage ranges from 6 mg to 15 mg daily. And the maximum recommended total daily dose is 20 mg, although doses up to 40 mg daily have been used.

Over time, your dosage may be adjusted based on your individual response and blood pressure goals. Your healthcare provider may also have you monitor your blood pressure at home.

Are there any dosage adjustments for medical conditions or interactions?

Prazosin is used to lower your blood pressure. So, it’s not unusual for you to take it with other blood pressure medications. But this combination can also increase your risk of hypotension (low blood pressure). In some cases, dosage adjustments may be necessary.

Dosage adjustment for drug interactions

Before adding another blood pressure medication, your prazosin dosage may be lowered to 1 mg to 2 mg three times daily. After adding the new medication, your prazosin dosage may be increased based on your blood pressure readings. This is to lower the risk of your blood pressure dropping too low. 

There are other medications that can also lower your blood pressure. One example is phosphodiesterase-5 (PDE-5) inhibitors, like sildenafil (Viagra). To manage this risk, your healthcare provider may have you take a lower PDE-5 inhibitor dose with prazosin.

Before starting any new medication or supplement, check with your healthcare provider or pharmacist first. Providing your current medication list can help them identify potential interactions before they happen.

What happens if you miss a dose of prazosin?

If you miss a dose of prazosin, take it as soon as you remember. But you should skip the missed dose if it’s close to your next regularly scheduled dose. 

Don’t try to double your dose or take more than prescribed by your healthcare provider. You can ask your provider if they have different instructions for you. 

Medication adherence is very important. If you’re having difficulty taking prazosin on time, speak with your healthcare provider or pharmacist. They can give you tips and tricks to help you stick with your regimen.

What should you do if you take too much prazosin?

Taking too much prazosin can cause serious problems, like hypotension. Low blood pressure can make you feel dizzy and increase the risk of falls. And in severe cases, it can affect how well blood gets to the rest of your body.

Older adults can be more sensitive to this effect, which is why alpha blockers are typically avoided if you’re age 65 or older.

If you think you might have taken too much prazosin, lay down on your back to help improve blood flow. Seek immediate medical attention if any symptoms feel severe or life-threatening. Otherwise, call your healthcare provider or Poison Control at 1-800-222-1222 right away. 

How to save on prazosin

Prazosin is available as both a brand-name and generic medication. With GoodRx, you can save over 40% off the average retail price of the generic version. You could pay as little as $9.44 with GoodRx at certain pharmacies.

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Written by:

Brian Leonard, PharmD, BCACP, BCGP

Brian Leonard earned his doctorate in pharmacy from the University of Florida College of Pharmacy and is board certified in Ambulatory Care and Geriatric Pharmacy.

Edited by:

Alyssa Billingsley, PharmD

Alyssa Billingsley, PharmD, is the director of pharmacy content for GoodRx. She has over a decade of experience as a pharmacist and has worked in clinical, academic, and administrative roles.

Reviewed by:

Austin Ulrich, PharmD, BCACP

Austin Ulrich, PharmD, BCACP, is a board-certified ambulatory care clinical pharmacist. In his early career, he provided direct patient care in a variety of settings, including hospital and community pharmacies, and in a primary care clinic as a clinical pharmacist.

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