Terazosin

Introduction

Written by Sarah Lewis, PharmD
Medically reviewed by Bryson Russell PharmD, MHSA, MSc
Updated on October 25, 2023

Terazosin (ter AY zoe sin) is a generic medication prescribed for benign prostatic hyperplasia (BPH), also called an enlarged prostate. It’s also used to treat high blood pressure in adults. Terazosin belongs to a group of drugs called alpha-blockers.

Side effects of terazosin

Terazosin may cause mild or serious side effects. More common mild side effects of terazosin and its serious side effects are listed below. This article doesn’t include all possible side effects of the drug. Side effects can vary based on your age, overall health, and any other medications you take.

To learn more about terazosin’s side effects, ask your doctor or pharmacist. You can also refer to the prescribing information for terazosin listed in the “Resources” section.

Mild side effects

More common mild side effects reported with terazosin are listed below.

This article doesn’t include all possible mild side effects of the drug. To learn more about terazosin’s side effects, refer to the prescribing information for terazosin listed in the “Resources” section.

With many drugs, mild side effects may go away within a few days or a couple of weeks. If the side effects are bothersome, tell your doctor or pharmacist. They may be able to suggest ways to manage them.

Terazosin oral capsule’s mild side effects include:

• dizziness
• drowsiness
• lack of energy
• stuffy or runny nose
• mild allergic reaction*

* For details about this side effect, see the “Interactions and warnings for terazosin” section.

Serious side effects

Serious side effects of terazosin are listed below.

This article doesn’t include all possible serious side effects of the drug. To learn more about terazosin’s side effects, refer to the prescribing information for terazosin listed in the “Resources” section.

With many drugs, serious side effects are possible but not common. If you have serious side effects from this drug, call your doctor right away. If you’re having severe symptoms or a medical emergency, call 911 or a local emergency number.

In general, terazosin’s serious side effects include:

• erectile dysfunction (ED)
• extreme sleepiness
• palpitations (a feeling of skipped or extra heartbeats)
• priapism (a long lasting erection that needs immediate treatment)
• sudden drop in blood pressure when standing or sitting up, which can lead to fainting
• swelling in the feet, legs, or arms due to fluid retention
• severe allergic reaction†

* For details about this side effect, see the “Interactions and warnings for terazosin” section.

Common questions about terazosin

Below you’ll find answers to a few commonly asked questions about terazosin.

What brand names are available for terazosin?

Currently, there isn’t a brand-name drug available for terazosin. Terazosin oral capsule is a generic version of the brand-name drug, Hytrin. But this drug is no longer on the market.

A generic medication is an identical copy of the active drug in a brand-name medication. (An active drug is the ingredient that makes a medication work.) Generic drugs are believed to be as effective and safe as brand-name drugs. And generic drugs typically cost less than brand-name drugs.

You can learn more about this by talking with your doctor or pharmacist.

Is terazosin similar to tamsulosin?

Yes, terazosin is similar to tamsulosin. They’re both alpha-blocker drugs that treat symptoms of benign prostatic hyperplasia (BPH), also called an enlarged prostate. Unlike terazosin, tamsulosin isn’t approved to treat high blood pressure.

Because they’re the same kind of drug, they have similar side effects and warnings. But tamsulosin doesn’t have the same effect on lowering blood pressure. So, it’s possible that your body may respond better to it if you have problems with low blood pressure.

To find out more about how these two drugs compare, talk with your doctor or pharmacist.

How does terazosin work? And how long does it take to start working?

Terazosin’s mechanism of action (the way it works) is to relax muscles in the bladder and the prostate. This helps urine flow more easily. It also relaxes blood vessels, which widens them and lowers blood pressure.

Terazosin will usually start working soon after you take it. But it can take up to 6 weeks to see the full effect of the drug.

If you’d like to know more about this, talk with your doctor or pharmacist.

Can terazosin be used for erectile dysfunction?

No. Terazosin isn’t approved for treating erectile dysfunction (ED). But alpha-blockers may help ease ED in some cases by treating an enlarged prostate. (Terazosin is an alpha-blocker).

Treatment with terazosin rarely can cause priapism (painful erection of the penis that lasts for hours). If this condition isn’t treated immediately, it can lead to permanent erectile dysfunction.

Some ED pills are used to help treat an enlarged prostate. For example, tadalafil is an ED treatment that’s also approved to treat an enlarged prostate.

If you have ED and an enlarged prostate, talk with your doctor about your treatment options.

Uses of terazosin

The Food and Drug Administration (FDA) approves prescription drugs such as terazosin for certain conditions. Approved uses for terazosin are described below.

Use for benign prostatic hyperplasia

Doctors may prescribe terazosin oral capsule to treat symptoms of benign prostatic hyperplasia (BPH). An enlarged prostate is another name for BPH. It’s used for this purpose in adult males.* It’s usually prescribed as a long-term treatment.

With BPH, the prostate gland increases in size. This gland helps make semen and surrounds your urethra (the tube through which urine and semen leave the body). As the prostate gland enlarges, it can block the urine flow through the urethra. Symptoms can include:

• dribbling after you urinate
• needing to urinate more often or waking to urinate during the night
• starting and stopping when you urinate
• having difficulty starting to urinate
• experiencing a weak urine stream

Terazosin can help relieve these symptoms.

* Sex and gender exist on spectrums. In this article, we use the term “male” to refer to a person’s sex assigned at birth.

Use for high blood pressure

Doctors may prescribe terazosin oral capsule for treating high blood pressure. It’s used for this purpose in adults. It’s usually prescribed as a long-term treatment.

With high blood pressure, people usually don’t have any symptoms. But having high blood pressure can cause serious health effects, including heart attack and stroke. Having high blood pressure may even lead to death. So, it’s important to check your blood pressure regularly. If you have high blood pressure, taking medication to lower it can help prevent heart attack, stroke, and other serious health effects.

Terazosin can be prescribed together with other medications to treat high blood pressure.

Interactions and warnings for terazosin

Below, you’ll find information about terazosin’s possible interactions and warnings.

Interactions of terazosin

Certain things may affect how a drug works. These include getting vaccines, consuming alcohol or certain foods, or taking the drug with other medications. This effect is called a drug interaction.

Before you take terazosin, ask your doctor to check for possible interactions. Be sure to tell them about any of the following you take or use:

• prescription or over-the-counter drugs
• vitamins, herbs, or supplements

To learn about drug-condition interactions, see the “Warnings for terazosin” section below.

Warnings for terazosin

Some people should not take terazosin, and others should take it cautiously.

Terazosin could cause harm to people with certain health conditions. This effect is called a drug-condition interaction. Other factors can also affect whether terazosin is a safe option for you.

Ask your doctor about specific warnings for terazosin, and be sure to tell your doctor about your:

• current health, including any allergies to medications
• past health conditions or surgeries

Allergic reaction

Terazosin can cause an allergic reaction in some people. Severe allergic reactions are rare but possible.

If you’ve had an allergic reaction to terazosin or any of its ingredients, your doctor will likely not prescribe terazosin. They can tell you about medications that are safer options for you.

A mild allergic reaction may cause the following symptoms:

• skin rash
• itchiness
• flushing (temporary warmth, redness, or deepening of skin color)

A severe allergic reaction may cause the following symptoms:

• swelling under your skin, usually in your hands, feet, eyelids, or lips
• swelling of your mouth, throat, or tongue, which can cause breathing problems

If you have an allergic reaction to terazosin, call your doctor right away. If you have severe symptoms, call 911 or a local emergency number.

Overdose of terazosin

You should not take more terazosin than your doctor prescribes. For some drugs, doing so may lead to harmful effects or overdose.

If you think you’ve taken too much terazosin, call your doctor or pharmacist right away. Or you could call 800-222-1222 to speak with someone at America’s Poison Centers. You can also use its online resource. If you have concerning symptoms, call 911 or a local emergency number immediately. You can also go to the closest emergency room.

Pregnancy or breastfeeding and terazosin

Information about terazosin and pregnancy and breastfeeding is described below.

Terazosin and pregnancy

It’s not known whether terazosin should be taken during pregnancy. If you’re planning a pregnancy or can become pregnant, talk with your doctor before taking this medication.

Terazosin and breastfeeding

It’s not known whether terazosin should be taken while breastfeeding. If you’re currently breastfeeding or planning to do so, talk with your doctor before taking this medication.

What to ask your doctor

Let your doctor know whether you have questions about terazosin or would like more details about it.

Here’s a list of some possible questions you may want to ask your doctor:

• What is the most important information I should know about terazosin?
• How does terazosin compare with other medications that could treat my condition?
• How should I take terazosin?

Resources

• Food and Drug Administration. (2023). Orange Book: Approved drug products with therapeutic equivalence evaluations. https://www.accessdata.fda.gov/scripts/cder/ob/index.cfm
• Terazosin capsules, USP. (2022). https://nctr-crs.fda.gov/fdalabel/services/spl/set-ids/f644558d-f04e-8d29-e053-2995a90a6cae/spl-doc

Disclaimer: Optum Perks has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.