Sounds like 'ter-AY-zoe-sin'

Easy-to-read medicine information about terazosin – what it is, how to take it safely and possible side effects.

Notification that terazosin is no longer available in New Zealand.
Talk to your healthcare provider about your treatment options. Read more about terazosin discontinuation
Type of medicine Also called
  • Medicine to treat enlarged prostate 
  • Terazosin
  • Apo-Terazosin

What is terazosin?

  • Terazosin is used to treat symptoms of an enlarged prostate, such as difficulty in beginning the flow of urine (pee), weak urine flow and the need to urinate (pee) often or urgently (including during the middle of the night).
  • It works by relaxing the muscles in your prostate and part of your bladder. It does not make the prostate smaller.
  • Terazosin is also used for other conditions such as high blood pressure, but this is less common. 
  • Terazosin is available as tablets.


  • The starting dose of terazosin is 1 milligram once a day.  
  • Your doctor will increase your dose slowly over a few weeks to 5–10 milligrams once a day. This allows your body to get used to the medicine.
  • Always take your terazosin exactly as your doctor has told you.
  • The pharmacy label on your medicine will tell you how much terazosin to take, how often to take it and any special instructions.

How to take terazosin

  • Take terazosin tablets with a glass of water at the same time each day.
  • Terazosin can cause dizziness and fainting, especially after the first dose or a dose increase. Take this dose at bedtime.
  • You can take terazosin with or without food.
  • To reduce your urinary symptoms, you must keep taking terazosin every day.
  • Limit drinking alcohol while you are taking terazosin. Alcohol can increase the chance of side effects such as feeling dizzy or faint.
  • If you forget your dose, take it as soon as you remember that day. But if it is nearly time for your next dose, just take the next dose at the right time. Do not take double the dose.

What are the side effects of terazosin?

Like all medicines, terazosin can cause side effects, although not everyone gets them. Often side effects improve as your body gets used to the new medicine.

Dizziness and fainting

Your first dose of terazosin or any increase in dose may make you feel faint, dizzy or lightheaded within a few hours of taking it. To reduce the impact of this effect:

  • take this dose at bedtime
  • be careful when moving from a sitting or lying position, as you are at risk of falls
  • stand up slowly from a sitting or lying position
  • if you feel dizzy or faint, remain lying down until these symptoms have gone
  • don't drive or use tools or machines until you know how this medicine affects you.

You should also limit or avoid alcohol while you are taking terazosin as alcohol can increase the chance of this side effect.

Other side effects

Side effects What should I do?
  • Headache
  • Try paracetamol, but first check that it can be taken with any other medicines you may take.
  • Tell your doctor if this bothers you.
  • Swollen feet or ankles
  • When you sit down, rest your legs on a low stool.
  • Tell your doctor if this bother you.
  • Changes in your heart beat (a pounding or racing feeling)
  • Chest pain 
  • Tell your doctor immediately or phone Healthline 0800 611 116.
Did you know that you can report a side effect to a medicine to CARM (Centre for Adverse Reactions Monitoring)? Report a side effect to a product


When certain medicines are taken together, an unintended reaction may occur. This is known as an interaction. Terazosin may interact with a few medicines and herbal supplements, so check with your doctor or pharmacist before starting any new medicines or herbal supplements.

Learn more

The following links provide further information on terazosin. Be aware that websites from other countries may contain information that differs from New Zealand recommendations.

Terazosin Patient Info, UK

Credits: Sandra Ponen, Pharmacist. Reviewed By: Nicola Rowbottom, Pharmacist, South Canterbury Last reviewed: 09 Jan 2017