Medication Information Leaflet

​What is this medication for?

Terazosin belongs to a group of medications known as alpha-1 blockers. It is used to treat benign prostatic hyperplasia, a condition where the prostate gland is enlarged due to a non-cancerous growth and this is caused by overproduction of a hormone called dihydrotestosterone. The prostate is close to the bladder, therefore enlargement of the prostate gland can affect the flow of urine. This leads to urinary symptoms such as a weak or interrupted urine flow, frequent or urgent need to urinate. The medication works by relaxing the muscles of the prostate gland and bladder exit to help relieve these symptoms.

It is also used to reduce high blood pressure in people with hypertension. It works in high blood pressure by widening (relaxing) blood vessel walls thus lowering your blood pressure.

This medication may also be used for other conditions. Check with your healthcare professional if you are unsure why you are given this medication.

How should I take/use this medication?

  • Do not stop taking your medication without checking with your healthcare professional.
  • You may take this medication with or without food. 
  • The first tablet of a new dose should be taken at bedtime, and subsequently at the same time each day.

What should I do if I forget to take/use this medication?

If you forget to take a dose, take it as soon as you remember. If it is almost time for your next dose, take only the usual dose. Do not double your dose or take two doses to make up for the missed dose.

What precautions should I take?

Inform your healthcare professional if: 
  • You are allergic to this medication or any of the other ingredients of this medication
  • You have heart problems
  • You ever feel dizzy or faint when you stand up, or if you have ever fainted after passing urine
  • You are undergoing cataract (cloudiness of the lens) eye surgery. Inform your eye specialist before the operation that you are taking or have previously taken the medication. The pupil may dilate poorly and the iris (the coloured part of the eye) may become floppy during the operation. It is important for the eye specialist to be aware of this as the operation may need to be carried out differently. 
  • You are taking medications belonging to PDE-5 Inhibitors class such as Sildenafil, Tadalafil or Vardenafil,  for the treatment of erectile dysfunction, a condition where you are unable to get or keep an erection firm enough to have sexual intercourse. You may experience dizziness or light-headedness, which may be caused by low blood pressure upon standing up quickly from a lying or sitting position. In order to reduce the likelihood that these symptoms occur, you should be on a regular daily dose of your alpha1-blocker medications (such as Tamsulosin, Alfuzosin, Terazosin) before you start medications for erectile dysfunction.

What are some common side-effects of this medication?

  • Dizziness, light-headedness or fainting 
    • When taking the medication for the first time, restarting treatment, or starting to take a higher dose, these side effects may occur. They may also occur when you are standing up quickly from a lying or sitting position. If you are affected by this, you should lie down until you feel better then sit for a few minutes before standing again to prevent these effects returning. These side effects usually go away and should not return once you have become used to taking your medication. 
  • Drowsiness
    • May affect your ability to drive and use machinery. Make sure your reactions are normal before you drive or do things require you to be alert.

What are some rare but serious side-effects that I need to seek medical advice immediately?

The symptoms of a drug allergy include one or more of the following: 
  • Swollen face/eyes/lips/tongue
  • Difficulty in breathing
  • Itchy skin rashes over your whole body
If you experience any of these symptoms, you should stop your medication and see your healthcare professional immediately.

What food or medication should I avoid when I take this medication?

Avoid drinking alcohol as it may increase the risk of dizziness, light-headedness or drowsiness. 

Inform your healthcare professional if you are taking or intend to take any other medication, supplements, traditional medications or herbal remedies. 

How should I store this medication?

Store in a cool and dry place, away from direct sunlight. Keep this medication away from children. 

How should I throw away this medication safely?

Pack this medication into a black trash bag and seal it tightly before throwing into the rubbish chute or bin.

If you take more than the recommended dose, please seek medical advice immediately. The information provided on this page does not replace information from your healthcare professional. Please consult your healthcare professional for more information.

This article is jointly developed by members of the National Medication Information workgroup. The workgroup consists of cluster partners (National Healthcare Group, National University Health System and SingHealth), community pharmacies (Guardian, Unity and Watsons) and Pharmaceutical Society of Singapore. The content does not reflect drug availability and supply information in pharmacies and healthcare institutions. You are advised to check with the respective institutions for such information.

Last updated on September 2019

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