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Terazosin: Uses, Side Effects and Dosage

Updated:
Facts
Status:
Prescription (Rx) Current status: Cancelled Post Market
Strength:
1 mg, 2 mg, 5 mg, 10 mg
ATC code:

Patient Medication Information: uses, side effects, how to take - Terazosin

ABOUT THIS MEDICATION

AUT THIS MEDICATION

What the medication is used for:

TERAZOSIN is used to treat:

  • Hypertension (high blood pressure)
  • Benign prostatic hyperplasia (enlargement of the prostate gland)

TERAZOSIN is for symptomatic benign prostatic hyperplasia (BPH) and not for prostate cancer. It is possible for men to have both BPH and prostate cancer at the same time. TERAZOSIN is not a treatment for prostate cancer.

Doctors usually recommend that men be checked for prostate cancer once a year when they turn 50 (or 40 if a family member

has had prostate cancer). These checks, including Prostate Specific Antigen (PSA), should continue while you are taking TERAZOSIN.

What it does:

TERAZOSIN works by relaxing blood vessels so that blood passes through them more easily. This helps to lower blood pressure.

TERAZOSIN also blocks smooth muscle receptors of the bladder neck and the prostate called alpha-1 adrenoceptors. This blockade causes the smooth muscles of the bladder neck and prostate to relax and decreases muscle tone. This can lead to a rapid improvement in urine flow and symptoms within a 2 week period.

When it should not be used:

TERAZOSIN should not be used if you are allergic to any component of TERAZOSIN including active ingredient and non-active ingredients.

What the medicinal ingredient is:

terazosin hydrochloride

What the non-medicinal ingredients are:

corn starch, crospovidone, lactose, magnesium stearate, povidone and talc.

In addition, the tablets contain:

2 mg: FD&C yellow No. 6 Lake.

5 mg: Black iron oxide, iron oxide red and yellow iron oxide.

10 mg: FD&C Blue No. 1 Lake and FD&C Blue No.2.

What dosage forms it comes in:

Tablets: 1 mg, 2 mg, 5 mg and 10 mg.

WARNINGS AND PRECAUTIONS

Serious Warnings and Precautions

  • TERAZOSIN should not be used if you have been diagnosed with micturition syncope (fainting shortly after or during urination).

BEFORE you use TERAZOSIN talk to your doctor or pharmacist if:

  • you have low blood pressure;
  • you are using sildenafil, tadalafil or vardenafil ;
  • you have liver problems;
  • you have kidney problems;
  • you have had or will have prostate surgery;
  • you have pancreatic cancer;
  • you are pregnant or nursing.

During initiation of TERAZOSIN therapy, after your TERAZOSIN dose has been increased, or after interruption of therapy when treatment with TERAZOSIN is resumed you should not drive, operate heavy machinery, or do any hazardous task, until you are used to the effects of TERAZOSIN. In these cases, for 12 hours after taking TERAZOSIN you should avoid situations where injury could result should fainting occur. If you begin to feel dizzy, sit or lie down until you feel better.

INTERACTIONS WITH THIS MEDICATION

Tell your doctor or pharmacist if you are taking or have recently taken any other medicines including natural health products, prescription and non-prescription medicines.

In general, you should avoid the use of phosphodiesterase (PDE5) inhibitors such as sildenafil, tadalafil or vardenafil when taking TERAZOSIN due to the risks of developing serious hypotension (low blood pressure).

Administration of TERAZOSIN with verapamil to hypertensive patients may result in low blood pressure and/or a rapid heartbeat.

Do not take these drugs with TERAZOSIN without your doctor’s advice.

PROPER USE OF THIS MEDICATION

Usual dose:

Follow your doctor’s instructions very carefully about how to take TERAZOSIN. The starting dose is 1 mg at bedtime. The 1 mg dose should be maintained during the first week of treatment, and should be taken every day as prescribed by your doctor. Your doctor will then gradually increase the strength of your prescription to 2 mg, 5 mg, or 10 mg depending on how well you respond. The maximum recommended daily dose is 20 mg per day.

You should see an effect on your symptoms in 2 to 4 weeks. While taking TERAZOSIN you should have regular check-ups to evaluate your progress regarding your BPH and to monitor your blood pressure.

Overdose:

In case of drug overdose, contact a health care practitioner, hospital emergency department or regional Poison Control Centre immediately, even if there are no symptoms.

If you or someone you know accidentally takes more than the stated dose, tell your doctor or hospital how much was taken and show them the tablets. Treat even small overdoses seriously.

Missed Dose:

If you forget to take a dose, take another as soon as you remember, unless it is almost time for your next dose. If it is, do not take the missed dose at all.

Never double-up on a missed dose.

Talk to your doctor if you have not taken TERAZOSIN for a few days. You may have to restart at the 1 mg dose. Be cautious about possible dizziness.

SIDE EFFECTS AND WHAT TO DO ABOUT THEM

Along with its needed effects, a medicine may cause some unwanted effects. These are referred to as “side effects”. Although not all of these side effects may occur, if they do occur they may need medical attention.

TERAZOSIN can cause a sudden drop in blood pressure after the very first dose. You may feel dizzy, faint, or "light-headed", particularly after you get up from bed or from a chair. This is more likely to occur after you have taken the first dose, but can occur at any time while you are taking the drug. It can also occur if you stop taking the drug and then restart treatment.

Because of this effect, your doctor may have told you to take TERAZOSIN at bedtime. If you take TERAZOSIN at bedtime but need to get up from bed to go to the bathroom, get up slowly and cautiously until you are sure how the medicine

affects you. It is also important to get up slowly from a chair or bed at anytime until you learn how you react to TERAZOSIN.

Other side effects with TERAZOSIN include back pain, constipation, diarrhea, drowsiness or sleepiness, dry mouth, flatulence, headache, impotence, indigestion, libido decreased, nasal congestion, nausea, urinary frequency, urinary incontinence primarily reported in postmenopausal women, weakness or weight gain.

SERIOUS SIDE EFFECTS, HOW OFTEN THEY HAPPEN AND WHAT TO DO ABOUT THEM
Symptom / effectTalk with your doctor or pharmacistStop taking drug and seek immediate emergency medical attention
Only if severeIn all cases
Abnormal, irregular or rapid heartbeat (palpitation)√

Allergic reaction

Swollen mouth, lips, tongue, eyes, extremities, throat or difficulty swallowing or breathing (signs of angioedema).

Intestinal angioedema may also occur and is characterized by abdominal pain (with or without nausea or vomiting). If you notice swelling or feel pain in these areas, inform your doctor immediately. You should also inform your doctor if you have unexplained fever, rash or itching.

√
Anxiety✓
Blurred or hazy vision✓
Chest pain✓
Decreased blood pressure or low blood pressure✓
Depression✓
Difficulty breathing or shortness of breath✓
Drowsiness or sleepiness✓
Fainting✓
Joint inflammation or joint pain✓
Permanent erection✓
“Puffiness” of the feet or hands, swelling✓
Rash✓
Sweating✓
Unknown bruising or increased bleeding after a cut✓
Urinary tract infection✓
Vomiting✓
Weakness✓

This is not a complete list of side effects. For any unexpected effects while taking TERAZOSIN, contact your doctor or pharmacist.

HOW TO STORE IT

Keep TERAZOSIN and all other medicines out of reach of children.

TERAZOSIN tablets should be stored at 15°C to 30°C.

Do not take your tablets after the expiry date shown on the label.

It is important to keep the TERAZOSIN in the original package.

Reporting Side Effects

You can help improve the safe use of health products for Canadians by reporting serious and unexpected side effects to Health Canada. Your report may help to identify new side effects and change the product safety information.

3 ways to report:

  • Online at MedEffect;
  • By calling 1-866-234-2345 (toll-free);
  • By completing a Consumer Side Effect Reporting Form and sending it by:
  • Fax to 1-866-678-6789 (toll-free), or
  • Mail to: Canada Vigilance Program

    Health Canada, Postal Locator 0701E Ottawa, ON

    K1A 0K9

    Postage paid labels and the Consumer Side Effect Reporting Form are available at MedEffect.

NOTE: Contact your health professional if you need information about how to manage your side effects. The Canada Vigilance Program does not provide medical advice.

MORE INFORMATION

This document plus the full product monograph, prepared for health professionals, can be obtained by contacting Sanis Health Inc. at 1-866-236-4076.

Sanis Health Inc.

Dieppe, New Brunswick

E1A 1P2

www.sanis.com

Last revised: August 7, 2015

About this document

Source: Health Canada – Drug Product Database (DPD) and product monographs · DIN (Drug Identification Number): 02350475

Revision date stated in the text: August 7, 2015

Found a mistake? Write to us via the contact page.

The information on this site does not replace the advice of a doctor or pharmacist.

Drug information for Terazosin

Rx or OTC
Prescription (Rx)?
DIN 02350475, 02350483, 02350491, 02350505
Schedule(s) PRESCRIPTION
Active ingredient(s) Terazosin (terazosin hydrochloride)
Dosage form(s) Tablet
Route(s) of administration Oral
Drug class (WHO ATC)
  1. G Genito urinary system and sex hormones
    1. G04 Urologicals
      1. G04C Drugs used in benign prostatic hypertrophy
        1. G04CA Alpha-adrenoreceptor antagonists, benign prostatic hypertrophy
          1. G04CA03 Terazosin
Company SANIS HEALTH INC
Current status Cancelled Post Market
Current status date July 18, 2022
Strengths and forms
DIN Strength Dosage form(s) Current status
02350475 1 MG Tablet Cancelled Post Market July 18, 2022
02350483 2 MG Tablet Cancelled Post Market July 18, 2022
02350491 5 MG Tablet Cancelled Post Market July 18, 2022
02350505 10 MG Tablet Cancelled Post Market July 18, 2022

Source: Health Canada – Drug Product Database (DPD) and product monographs, data as of November 1, 2026. Data from the Health Canada Drug Product Database, as published there. Not a substitute for the advice of a doctor or pharmacist.