Prazosin:side effects,dosage,precautions, and manufacturers

Prazosin is a medication primarily used to treat high blood pressure (hypertension) and symptoms of an enlarged prostate (benign prostatic hyperplasia, BPH). It is also sometimes used to help manage the symptoms of post-traumatic stress disorder (PTSD) such as nightmares and episodes of fear or anxiety. Prazosin is an alpha-blocker, which works by relaxing certain muscles and improving blood flow.

Prazosin side effects

As with any medication, prazosin can cause side effects. Here are some of the more common ones:

Prazosin side effects
Prazosin side effects
  1. Dizziness or lightheadedness: This can occur when getting up suddenly from a lying or sitting position, which can lead to falls. It’s important to get up slowly to prevent this.
  2. Headache: Some individuals may experience mild to moderate headaches while taking prazosin.
  3. Weakness or fatigue: Prazosin can sometimes cause a feeling of general tiredness or lack of energy.
  4. Nausea: Some patients may feel some nausea, which can sometimes be accompanied by vomiting.
  5. Palpitations: Some individuals may experience an unusual awareness of their heartbeat, which can feel like skipped or rapid heartbeats.
  6. Constipation: Prazosin can cause constipation, which may require the use of laxatives or other measures to manage.
  7. Ejaculation problems: Prazosin can affect ejaculation, leading to difficulties in this area.
  8. Dry mouth: Some patients may experience a dry or cottonmouth feeling.
  9. Blurred vision: In some cases, prazosin can cause blurred vision or other vision changes.
  10. Runny nose: A stuffy or runny nose can occur as a side effect of prazosin.
  11. Swelling of the feet and lower legs (edema): Prazosin can cause fluid retention, leading to swelling, particularly in the lower extremities.
    Less common but more serious side effects can also occur. These include:
  12. An erection that lasts longer than four hours (priapism): This is a medical emergency and requires immediate attention.
  13. Allergic reactions: Although rare, allergic reactions to prazosin can occur. Symptoms may include itching, rash, hives, swelling of the face, lips, tongue, or throat, and difficulty breathing.

Prazosin is typically taken by mouth and is available in the form of tablets. The dosage and administration of prazosin will be determined by a healthcare provider, and it’s important to follow their instructions exactly. Here are general guidelines for usage and some precautions:


  • Hypertension: The usual starting dose is 1 mg taken at bedtime. This may be increased gradually, usually every few days, to achieve the desired blood pressure control. The maintenance dose is typically 6 to 15 mg per day, divided into two or three equal doses.
  • Benign Prostatic Hyperplasia (BPH): The starting dose is often 1 mg twice daily, which can be increased to 2 mg twice daily after one to two weeks, if necessary.
  • Post-Traumatic Stress Disorder (PTSD): For the treatment of symptoms associated with PTSD, such as nightmares, the starting dose is often 1 mg at bedtime. This may be increased to 2 mg, and then 5 mg if needed, based on response and tolerance.


  • Prazosin should be taken with a glass of water, with or without food, as directed by your healthcare provider.
  • It’s important to take prazosin at the same times each day to maintain a consistent level of the medication in the body.

Precautions and Warnings:

  • Before taking this medicine, inform your healthcare provider if you have liver disease, kidney disease, low blood pressure, prostate cancer, or if you are allergic to any alpha-blockers.
  • Prazosin can cause dizziness, lightheadedness, and fainting, especially when you first start taking it or when your dose is changed. Rise slowly from a sitting or lying position to prevent falls.
  • Avoid driving, operating heavy machinery, or engaging in other potentially dangerous activities until you know how prazosin affects you.
  • Alcohol can increase some of the side effects of this medicine, particularly dizziness and fainting. It’s best to limit or avoid alcohol while taking this medication.
  • Tell your healthcare provider about all other medications you are taking, including over-the-counter drugs, vitamins, and herbal supplements, as they can interact with prazosin.
  • this medicine may interact with other medications, such as diuretics, beta-blockers, and certain antidepressants, so it’s important to inform your healthcare provider of all the medications you are taking.
  • If you are planning surgery, including dental surgery, inform the surgeon or dentist that you are taking this medicine, as it may affect the anesthesia and your blood pressure during the procedure.
  • Suddenly stopping this medicine can cause a sudden increase in blood pressure. Do not stop taking this medication without consulting your healthcare provider.
  • Women who are pregnant or planning to become pregnant should discuss the risks and benefits of taking this medicine with their healthcare provider, as the effects on the fetus are not fully known.
  • It’s not known if this medicine passes into breast milk, so breastfeeding mothers should consult their healthcare provider before taking this medication.

Prazosin for nightmares

Prazosin is sometimes prescribed to treat nightmares associated with post-traumatic stress disorder (PTSD) because of its unique mechanism of action within the brain. While this medicine is primarily an alpha-1 adrenergic receptor antagonist, which is why it is used to treat conditions like hypertension and benign prostatic hyperplasia, its effectiveness in treating nightmares in PTSD may be due to its ability to block alpha-1 receptors in the brain that are involved in the fear response.

Prazosin for nightmares
Prazosin for nightmares

In PTSD, the body’s stress response system can become overactive, leading to a range of symptoms, including nightmares. These nightmares are often vivid, recurring, and related to the traumatic event experienced by the individual. The activation of noradrenaline (norepinephrine) in the brain, particularly in areas involved in the processing of fear and memory, such as the amygdala and hippocampus, is thought to contribute to the frequency and intensity of these nightmares.

By blocking alpha-1 receptors, this medicine can interfere with the enhanced noradrenergic activity in these brain regions, which may help reduce the vividness and frequency of nightmares. This action can lead to fewer disruptions in sleep and an overall improvement in the quality of life for individuals with PTSD.

While prazosin can be effective for some individuals in reducing nightmares, it may not be effective for everyone, and its use in treating this specific symptom of PTSD should be guided by a healthcare professional. Additionally, the exact mechanism by which this medicine reduces nightmares is not fully understood, and research in this area is ongoing.


Prazosin, as an alpha-1 adrenergic receptor antagonist, has several advantages when compared to other medications in its class. Here are some of the potential benefits of this medicine over similar drugs:

the potential benefits of prazosin
the potential benefits of prazosin
  1. Selective Action: Prazosin is more selective for alpha-1 receptors in the peripheral vasculature compared to some other alpha-blockers. This selectivity may result in fewer side effects related to alpha-blockade in other areas of the body, such as the smooth muscles in the prostate or the bronchi.
  2. Oral Absorption: this medicine has good oral absorption, which means it can be taken effectively by mouth, offering convenience for patients.
  3. Immediate-Release vs. Extended-Release: this medicine is available in an immediate-release formulation, which allows for more flexibility in dosing and can be adjusted more quickly in response to the patient’s needs.
  4. Fewer Interactions: this medicine may have fewer drug interactions compared to some other alpha-blockers, making it a safer choice for patients taking multiple medications.
  5. Potential for Nightmare Reduction: Prazosin has been found to be effective in reducing nightmares associated with post-traumatic stress disorder (PTSD), a unique indication not commonly associated with other alpha-blockers.
  6. Prostate Symptoms: this medicine can also help relieve symptoms of an enlarged prostate, such as difficulty urinating, without the sedative effects that may be associated with some other medications used for this condition.
  7. Blood Pressure Control: Prazosin is effective in controlling blood pressure, particularly in patients with hypertension, and it may have a more favorable effect on blood pressure control during the periods of activity (e.g., daytime) compared to some other alpha-blockers.


In the United States, several pharmaceutical companies manufacture and sell prazosin. Here are some of the major prazosin manufacturers and a brief introduction to each:

  1. Pfizer Inc.
    • Pfizer is a globally renowned pharmaceutical company founded in 1849, headquartered in New York City. Pfizer’s brand name for prazosin is Minipress. Pfizer has extensive experience in drug development and production, with products covering multiple therapeutic areas.
  2. Teva Pharmaceutical Industries Ltd.
    • Teva is an Israeli pharmaceutical company and one of the world’s largest generic drug manufacturers. Teva produces and sells various generic drugs, including prazosin. Teva is committed to providing high-quality and affordable medications to meet the needs of patients worldwide.
  3. Mylan N.V.
    • Mylan is a global pharmaceutical company headquartered in Pennsylvania, USA. The company focuses on producing generic and biosimilar drugs. Mylan’s product line is extensive, including various cardiovascular medications such as prazosin.
  4. Actavis
    • Actavis is a globally known manufacturer of generic and branded drugs, now acquired by Teva. Actavis offers a wide range of medications across multiple therapeutic areas, including prazosin.
  5. Sandoz
    • Sandoz is the generic pharmaceuticals division of Novartis, headquartered in Switzerland. Sandoz produces and sells a variety of generic drugs, including prazosin. Sandoz is committed to improving global patient health by providing high-quality generic medications.

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top