NZ Formulary

Prazosin

praz-oh-sin

What does it do?

Prazosin is used to treat trouble peeing caused by an enlarged prostate. It is also used for other conditions such as high blood pressure.

Before you start

  • Tell your doctor if you have heart problems, low blood pressure, or problems with fainting.
  • Tell your doctor if you are pregnant, planning to become pregnant, or breastfeeding.

How should you take it?

Take prazosin regularly as directed with a glass of water. You can take it with or without food.

What if you forget a dose?

If it is nearly time for your next dose, skip the missed dose and take your next dose at the usual time. Otherwise, take the missed dose as soon as you remember. Do not take two doses at the same time.

Can you take other medicines?

Some medicines available without a prescription may react with prazosin including:

  • sildenafil (e.g. Viagra®) or similar medicines

Tell your pharmacist or doctor about all medicines or treatments that you may be taking, including vitamins, herbal products or recreational drugs.

What side effects might you notice?

Side EffectsRecommended action

Tiredness or weakness

Runny or blocked nose

Dry orgasm

Tell your doctor if troublesome

Lightheaded or dizzy after standing up

Stand up slowly. If it continues, or is severe, tell your doctor

If you notice any other effects, discuss them with your doctor or pharmacist.

Other information:

  • Prazosin can impair your ability to do tasks such as driving or using machines. Alcohol makes this worse. Discuss your risk with your health professional. (search NZTA - Are you safe to drive?)
  • If you are having eye surgery (e.g. cataract operation), tell your doctor that you are taking prazosin.