prazosin
Prazosin (Minipress) is an alpha blocker that's used to lower high blood pressure. It works by relaxing your blood vessels, so blood flows through more easily. Prazosin (Minipress) is taken by mouth, typically 2 to 3 times a day. But it isn't a first-choice medication to lower blood pressure because it can cause bothersome side effects like dizziness, headache, and sleepiness.
What is Prazosin (Minipress)?
What is Prazosin (Minipress) used for?
High blood pressure (hypertension)
How Prazosin (Minipress) works
Prazosin (Minipress) is an alpha blocker. It lowers blood pressure by relaxing blood vessels. This helps blood flow smoothly through the body.
Drug Facts
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What are the side effects of Prazosin (Minipress)?
Common Side Effects
- Dizziness (10%)
- Headache (8%)
- Drowsiness (8%)
- Lack of energy (7%)
- Weakness (7%)
- Pounding heart (5%)
- Nausea (5%)
Other Side Effects
- Vomiting
- Diarrhea
- Constipation
- Swelling
- Trouble catching your breath
- Feeling faint
- Spinning sensation
- Depression
- Nervousness
- Rash
Serious Side Effects
- Priapism: painful erection that lasts more than 4 hours
Source: FDA
More on Prazosin (Minipress) side effects
The following side effects have also been reported
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
More common
Dizziness or lightheadedness, especially when getting up from a lying or sitting position
fainting (sudden)
Less common
Loss of bladder control
pounding heartbeat
swelling of the feet or lower legs
Incidence not known
Painful or prolonged erection of the penis
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
More common
Drowsiness
headache
lack of energy
Less common
Dryness of the mouth
nervousness
unusual tiredness or weakness
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
Pros and cons of Prazosin (Minipress)
Pros
Taken by mouth
Can be taken with or without food
Available as a lower-cost generic medication
Cons
Not a first-choice option for lowering blood pressure
Older adults are at higher risk for side effects, like dizziness or drowsiness
Taken multiple times a day
Pharmacist tips for Prazosin (Minipress)
Prazosin (Minipress) can make you feel dizzy or light-headed, especially when you start taking it for the first time and when your dose is raised. If you’ve been sitting or lying down, get up slowly to avoid the risk of falling.
Because prazosin (Minipress) can cause dizziness, avoid driving and doing things that may be dangerous until your body gets used to the medication.
Prazosin (Minipress) can raise your risk of falls since it causes dizziness. If you fall down and hit your head or are in pain after a fall, the safest choice is to seek medical care right away. This is because there could be bleeding inside the body, and it’s best to have your provider check for these injuries. This is particularly important if you’re taking blood thinners, which can raise your risk for bleeds that are difficult to stop.
If your provider is adding on another blood pressure medication to prazosin (Minipress), they might lower your dose of prazosin (Minipress) to 1 mg or 2 mg three times a day. This is to lower your risk of the dizziness or fainting that might happen if your blood pressure drops too low. If needed, they'll raise your prazosin (Minipress) dose over time.
If you want to stop taking prazosin (Minipress), let your provider know. Don't suddenly stop taking this medication. Doing so can cause your blood pressure to rise too quickly. Your provider can help you stop this medication safely by lowering the dose slowly over time.
Frequently asked questions about Prazosin (Minipress)
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What are the risks and warnings for Prazosin (Minipress)?
Prazosin (Minipress) can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.
Dangerously low blood pressure and risk of fainting
Risk factors: Age 65 years or older | Taking other blood pressure medications | Drinking alcohol
Prazosin (Minipress) can cause you to feel dizzy or faint when you stand up after sitting or lying down. This is because your blood pressure might change quickly when you suddenly change positions (also known as orthostatic hypotension). The risk of this side effect is highest after your first dose of prazosin (Minipress), whenever your dose is raised, or when your provider add on another blood pressure medication. Typically, you tend to feel most dizzy within 90 minutes of taking a dose.
To minimize your risk of dizziness or fainting, you provider will have you start with a lower dose of prazosin (Minipress) and raise your dose slowly over time, if needed. Avoid activities that could be dangerous for the first 24 hours after you start prazosin (Minipress). This includes driving, operating heavy machinery, and exercising. If you feel dizzy, lightheaded, or like your heart is pounding, make sure to stop doing anything that could be hazardous. If these symptoms are bothersome, let your healthcare provider know because they might need to change your dose.
Painful erection (priapism)
In some rare cases, prazosin (Minipress) can cause a painful erection (also known as priapism) that continues for more than 4 hours. If this happens to you, contact your provider right away to avoid the risk of permanent erectile dysfunction.
Eye problems during surgery
Risk factors: Cataract surgery
If you take prazosin (Minipress) and plan to get cataract eye surgery, let your provider know. In some rare cases, this medication can cause changes to your iris, a condition called Intraoperative Floppy Iris Syndrome (IFIS). Keep in mind that prazosin (Minipress) is probably less likely to cause IFIS than other similar medications, like tamsulosin (Flomax). You don’t need to stop taking prazosin (Minipress) before the surgery, but your surgeon needs to adjust how they perform the operation. Letting your provider know ahead of time can help them prepare accordingly.
Prazosin (Minipress) dosage forms
Typical dosing for Prazosin (Minipress)
The typical starting dose is 1 mg by mouth 2 to 3 times a day. If needed, your provider will adjust your dose slowly over time. The typical recommended dose ranges from 6 mg to 15 mg daily total, divided into smaller doses and taken throughout the day. The maximum recommended dose is 20 mg daily total.
More on Prazosin (Minipress) dosage forms
Interactions between Prazosin (Minipress) and other drugs
Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Acebutolol
- Alprenolol
- Atenolol
- Betaxolol
- Bevantolol
- Bisoprolol
- Bucindolol
- Carteolol
- Carvedilol
- Celiprolol
- Dilevalol
- Esmolol
- Labetalol
- Levobunolol
- Mepindolol
- Metipranolol
- Metoprolol
- Nadolol
- Nebivolol
- Oxprenolol
- Penbutolol
- Pindolol
- Propranolol
- Sildenafil
- Sotalol
- Talinolol
- Tertatolol
- Timolol
- Vardenafil
How much does Prazosin (Minipress) cost?
What are alternatives to Prazosin (Minipress)?
High blood pressure (hypertension)
Difficulty urinating caused by an enlarged prostate (benign prostatic hyperplasia, BPH)
High blood pressure
Enlarged prostate (benign prostatic hyperplasia, BPH)
High blood pressure - immediate-release tablet only
What is the latest news about Prazosin (Minipress)?
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References
Best studies we foundHoltzheimer, P., et al. (2023). Clinician’s guide to medications for PTSD. U.S. Department of Veterans Affairs.
Paiva, H. S., et al. (2021). Using prazosin to treat posttraumatic stress disorder and associations: A systematic review. Psychiatry Investigation.
Pfizer Inc. (2015). Minipress® capsules (prazosin hydrochloride) for oral use [package insert].
Raskind, M. A., et al. (2018). Trial of prazosin for post-traumatic stress disorder in military veterans. The New England Journal of Medicine.
Saad, M., et al. (2022). Alpha blocker-associated intraoperative floppy iris syndrome. The Senior Care Pharmacist.
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