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Drug Class: Commonly Known As: Category:
Alpha 1 blocker Hytrin

Terazosin - What is it 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.

Terazosin - Side Effects, Precautions, and Contraindications

What side effects can Terazosin cause?

  • ​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.


  • Swollen face/eyes/lips/tongue
  • Difficulty in breathing
  • Itchy skin rashes over your whole body


Before taking Terazosin, what precautions must I follow?

​Inform your healthcare professional if:

  • 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 food or medicine must I avoid when I take Terazosin?



Terazosin - Dosage and How to Use

How should Terazosin be used?

  • 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 miss a dose?

​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 should I do if I overdose?

Terazosin - Handling

How should I handle Terazosin safely?

Terazosin - Storage

How should I store Terazosin?


How should I dispose of Terazosin safely?


Terazosin - Additional Information

  • Updated on Monday, September 30, 2019
  • Article contributed by PSS National Medication Information Workgroup


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