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Minipress Side Effects

Generic Name: prazosin

Note: This page contains information about the side effects of prazosin. Some of the dosage forms included on this document may not apply to the brand name Minipress.

In Summary

Common side effects of Minipress include: dizziness. Other side effects include: syncope and drowsiness. See below for a comprehensive list of adverse effects.

For the Consumer

Applies to prazosin: oral capsule, oral tablet

In addition to its needed effects, some unwanted effects may be caused by prazosin (the active ingredient contained in Minipress). In the event that any of these side effects do occur, they may require medical attention.

Major Side Effects

You should check with your doctor immediately if any of these side effects occur when taking prazosin:

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
  • Chest pain
  • trouble breathing
Incidence not known:
  • Painful or prolonged erection of the penis

Minor Side Effects

Some of the side effects that can occur with prazosin may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:

More common:
  • Drowsiness
  • headache
  • lack of energy
Less common:
  • Dryness of the mouth
  • nervousness
  • unusual tiredness or weakness
  • Frequent urge to urinate
  • nausea

For Healthcare Professionals

Applies to prazosin: compounding powder, oral capsule


The most common adverse reactions were postural hypotension, dizziness, headache, drowsiness, lack of energy, weakness, palpitations, and nausea.[Ref]


Very common (10% or more): Postural hypotension (up to 14%)
Common (1% to 10%): Palpitations, tachycardia, orthostatic hypotension
Uncommon (0.1% to 1%): Angina pectoris
Rare (less than 0.1%): Bradycardia, flushing, hypotension, vasculitis
Frequency not reported: Angina exacerbation, myocardial infarction[Ref]

Nervous system

Very common (10% or more): Dizziness (up to 10.3%)
Common (1% to 10%): Drowsiness, headache, faintness, syncope, vertigo
Uncommon (0.1% to 1%): Paresthesia, tinnitus
Rare (less than 0.1%): Narcolepsy worsened[Ref]


Common (1% to 10%): Lack of energy, weakness, asthenia
Rare (less than 0.1%): Fever, pain
Frequency not reported: Malaise[Ref]


Common (1% to 10%): Constipation, diarrhea, dry mouth, nausea, vomiting
Uncommon (0.1% to 1%): Abdominal discomfort and/or pain
Rare (less than 0.1%): Pancreatitis[Ref]


Common (1% to 10%): Dyspnea, nasal congestion, epistaxis[Ref]


Common (1% to 10%): Depression, nervousness
Uncommon (0.1% to 1%): Insomnia
Rare (less than 0.1%): Hallucinations[Ref]


Common (1% to 10%): Blurred vision, sclera reddened
Uncommon (0.1% to 1%): Eye pain
Frequency not reported: Pigmentary mottling, serious retinopathy, cataract development, cataract disappearance[Ref]


Common (1% to 10%): Urinary frequency, impotence
Rare (less than 0.1%): Incontinence, priapism[Ref]


Common (1% to 10%): Rash
Uncommon (0.1% to 1%): Diaphoresis, pruritus, urticaria
Rare (less than 0.1%): Alopecia, lichen planus[Ref]


Common (1% to 10%): Edema[Ref]


Uncommon (0.1% to 1%): Arthralgia[Ref]


Rare (less than 0.1%): Allergic reaction, positive antinuclear antibody titer[Ref]


Rare (less than 0.1%): Gynecomastia[Ref]


Rare (less than 0.1%): Liver function abnormalities[Ref]


1. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

2. Cerner Multum, Inc. "Australian Product Information." O 0

3. "Product Information. Minipress (prazosin)." Pfizer US Pharmaceuticals, New York, NY.

Not all side effects for Minipress may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.