> Western Medicines > Prazosin

What is Prazosin for?

Prazosin belongs to a class of medications called alpha-blockers (like Tamsulosin) that causes vasodilation and therefore it is mainly indicated for hypertension, benign prostatic hyperplasia (BPH), and the Raynaud phenomenon. It can also be used for treating post-traumatic stress disorder, nightmares and sleep disorders.

How to use it?

Prazosin is taken by mouth as conventional tablets. For patients who are taking this drug for the first time, it is advised to take it before bedtime to reduce the chance of symptomatic hypotension.


When used for high blood pressure (hypertension), the usual adult starting dose of Prazosin is 1 mg 2-3 times daily. Your doctor will then gradually increase the dose as needed. The maximum daily dose is 20 mg.


For other uses of Prazosin, adult dosing can begin at 0.5-1 mg daily at bedtime.

What are the side effects of Prazosin?

Common side effects of Prazosin are low blood pressure, dizziness, headache, swelling of limbs, and nasal congestion.

Who should not take Prazosin?

  • People who are allergic to quinazolines, Prazosin, or any formulation ingredient.
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Where to buy Prazosin in Hong Kong?

In Hong Kong, Prazosin is a prescription only medicine, and requires a prescription from a doctor to be purchased in a pharmacy. It can also be obtained from doctors. To find a pharmacy near you, refer to the list of pharmacies (“Authorized Sellers of Poisons”) from the Hong Kong Department of Health.


For more information about drug names and ingredients, you can visit Hong Kong’s Drug Office at https://www.drugoffice.gov.hk

Need more information?

For detailed information about the use of Prazosin in children, pregnancy and breastfeeding, and for questions about drug interactions, please check with your pharmacist or doctor.

Disclaimer: our goal is to provide you with the most relevant drug information and common dosage for Hong Kong. This information does not constitute medical advice. For specific treatment recommendations and advice, always discuss with your doctor or pharmacist, and follow the instructions included with your specific medicine.

Brands in Hong Kong
Available dosage
  • 1mg / 2mg / 5mg (Tablets)
Drug class
Vasodilators, Antihypertensives
Sub class
Alpha Blockers
Other drugs in same class
Used for: Cerebrovascular disease, Dementia, Peripheral circulatory disorders
Chinese name: