Terazosin (Oral)

Terazosin is a medication that belongs to a group of drugs known as alpha blockers, which are used to treat hypertension.


Terazosin is a medication that belongs to a group of drugs known as alpha blockers, which are used to treat hypertension. This medication is also used in the treatment of benign prostate enlargement. In the US, Terazosin is sold under the brand name, Hytrin.

Hypertension makes the heart and arteries work harder. This can eventually affect their function. Prolonged hypertension can cause damage to the arteries in the heart, brain, and kidneys. This can cause kidney failure, a stroke, or a heart attack. The likelihood of heart failure is also greatly increased by hypertension. Terazosin works effectively by lowering the blood pressure by relaxing the muscles. This allows blood to flow more easily, thus relieving dangerous pressure on the heart and arteries.

Patients who are prescribed Terazosin for high blood pressure control may be advised that they need to remain on this medication for the rest of their lives.

This medication is also used in the treatment of a condition called BPH, or 'benign prostatic hyperplasia'. BPH is a problem that commonly occurs in older men. The prostate gland lies underneath the bladder. When the prostate becomes enlarged, the muscles contained within the gland become tightened. This tightening can restrict the tubes that allow urine to drain away from the bladder. Men with prostate enlargement often have problems when urinating, including a weak urine stream, or a feeling that the sufferer cannot empty their bladder fully. Terazosin works by relaxing the prostate's muscles and allowing the bladder to open correctly, thus increasing the urine flow and decreasing the patient's symptoms.

It should be noted that this medication will not reduce the size of the prostate, and it may actually carry on growing, so that the symptoms will gradually worsen. Surgery may be required in the future to correct the problem.

Terazosin is only available on prescription from your doctor and comes in capsule or tablet form.

Conditions treated

  • hypertension
  • benign prostatic hyperplasia (BPH)

Type of medicine

  • alpha blocker
  • tablet
  • capsule
  • liquid-filled capsule


Although taking Terazosin will be beneficial to your condition, it is possible that you may experience a few side-effects when you first begin taking it. Be sure to inform your doctor if you have ever suffered from allergic reactions to any other form of medication or if you have any known allergies to certain foods, preservatives, animal derivatives, or dyes.

It is not unusual for patients to begin to feel slightly dizzy when they first begin treatment with this medication.

There are also a variety of side-effects in patients taking this medication that are seen less commonly, including:

  • pains in the chest
  • dizziness when getting up from a sitting position or from lying down
  • sudden fainting episodes
  • fast, pounding, or irregular heartbeat
  • shortness of breath
  • swelling in the lower legs or feet
  • weight gain

Some of the side-effects listed below that are caused by Terazosin often resolve themselves without the need for further medical treatment, as your body gets used to the medication. Ask your doctor's advice on how to prevent or manage these effects if they are persistent or particularly bothersome.

  • feeling unusually tired, drowsy or weak
  • headaches
  • blurred or double vision
  • pain the back or joints
  • nausea and vomiting
  • stuffy nose

This list of recognised side-effects that have been experienced by patients taking Terazosin is not necessarily exhaustive. If you feel that the condition you are being treated for is not getting better, or you think that you are actually feeling worse since you started your course of treatment, ask your doctor for advice.


Terazosin is only available on prescription from your doctor. The medication comes in tablet or capsule form.

The dose of Terazosin that is prescribed by your doctor will vary between patients, depending on the condition being treated. Always follow your doctor's instructions or the directions given on the dispensed product label. The dosage outlined below only reflects the average recommended dose for this medication. Do not change the dose that you have been prescribed by your doctor, unless you are advised to do so.

Take Terazosin exactly as you are instructed to by your doctor. Do not take more medication than you have been prescribed. Do not take the medicine more frequently, or for a longer period than directed. To do so could increase the risk of you experiencing side-effects.

This drug will come with patient guidelines enclosed in the packaging. Be sure to read the guidelines thoroughly, and ask your treating physician if you have any queries.

Do not share your medication with anyone else.

For benign enlargement of the prostate

  • adults: initially, take 1mg at bedtime, then 5mg to 10mg once daily

For high blood pressure

  • adults: initially, take 1mg at bedtime, then 1mg to 5mg once daily
  • children: use and dosage should be determined by the treating physician

Try to take your medication at the same times each day. You may take your medication with or without food.

If you miss a dose of Terazosin, you should try to take it as soon as possible. If the time of your next dose is near, omit the missed dose and revert to your usual dosing schedule. Do not take a double dose.

If you or someone else overdoses on this medication and exhibits serious symptoms, including loss of consciousness or breathing difficulties, call 911 immediately.

If you are taking this medication for high blood pressure, your doctor may recommend weight loss in addition to a diet that is suitable. If you plan on changing your diet, always discuss your intentions with your doctor first. It is very important that you continue to take your medication, even if you feel much better. You must also keep all your scheduled check-up appointments with your doctor. These visits allow your doctor to monitor your progress on this drug and give you opportunity to discuss any troublesome side-effects that you may be experiencing.

The medication will not cure your high blood pressure, but it can help to control and manage it. Do not stop taking your medication, unless advised to do so by your doctor.

If you are taking Terazosin for benign enlargement of the prostate, remember that the drug will not shrink the size of your prostate, but it can help to relieve the symptoms. You should expect to wait up to six weeks before you notice an improvement.

Many patients who develop high blood pressure and who are prescribed Terazosin may have to remain on the drug for the rest of their lives. If this applies to you, you should work with your doctor to refine the dose and thus minimise any unpleasant side-effects that you may experience.

Major drug interactions

Some forms of medication should not be used at the same time. However, in other cases certain medications can be used together, even if an interaction is known to occur. Under these circumstances, your doctor may decide to change the dose of one or more of your prescribed drug therapies or may advise you to take other precautions.

If you are prescribed Terazosin, it is extremely important that you tell your doctor if you are already taking any of the medication listed below. The following drugs are known to have an interaction with Terazosin:

  • Vardenafil
  • Timolol
  • Tertatolol
  • Talinolol
  • Tadalafil
  • Sotalol
  • Sildenafil
  • Propranolol
  • Pindolol
  • Penbutolol
  • Oxprenolol
  • Nebivolol
  • Nadolol
  • Metoprolol
  • Metipranolol
  • Mepindolol
  • Levobunolol
  • Labetalol
  • Esmolol
  • Dilevalol
  • Celiprolol
  • Carvedilol
  • Carteolol
  • Bucindolol
  • Bisoprolol
  • Bevantolol
  • Betaxolol
  • Atenolol
  • Asenapine
  • Alprenolol
  • Acebutolol

This list is not necessarily all-inclusive. If you already taking a medicine that is not included in the above list, tell your doctor before taking Terazosin.


In addition to discussing any allergies and other drugs that you are taking, you should also mention to your doctor any existing health conditions that you have. When deciding to use this medication, you should weigh up the risks and benefits of taking it. Your doctor will discuss the pros and cons of using Asenapine with you in greater detail.

Tell your doctor if you have ever experienced any allergic reactions to any form of prescription or non-prescription medication, herbal remedies, or vitamin supplements. You should also mention any allergies that you have to foods, preservatives, dyes, or animal derivatives.

You should have regular blood tests to monitor your progress and to check for any side-effects while you are taking this medication. Your doctor will advise you further on this.

If you are taking any drugs to treat pulmonary hypertension or erectile dysfunction, your blood pressure may become too low if you start taking Terazosin at the same time. This can lead to dizziness and fainting. Your physician may need to alter the dosage of your medication to keep this risk to a minimum.

Some over-the-counter medications contain ingredients that can raise your blood pressure. If you intend using products such as cough and cold remedies, diet aids, or NSAIDs, including ibuprofen or naproxen, tell your pharmacist or ask your doctor for advice.

There are some medical problems that may affect the use of Terazosin, including:

  • angina - Terazosin can make this condition worse
  • severe heart disease - Terazosin can make this condition worse
  • kidney disease - kidney disease can have increased sensitivity to the effects of Terazosin

Some people, especially the elderly, feel dizzy or faint when getting up quickly from a lying or sitting position. Take the first dose of your medicine at bedtime, and get up more slowly following subsequent doses. Try to avoid drinking alcohol, standing for long periods of time, exercising, or staying outside during hot weather.

Terazosin can make some people feel sleepy or less alert than usual. This effect may reduce as your body becomes acclimatised to the medication, but in the meantime you should exercise caution when driving or operating machinery.

You should tell your doctor if you have a history of any of the following medical conditions:

  • low blood pressure
  • fainting
  • cataracts
  • glaucoma

If you are scheduled to undergo eye surgery, be sure to tell your doctor or surgeon if you have ever taken this medication.

It is unknown if Terazosin can adversely affect unborn babies. If you are pregnant or if you are planning on becoming pregnant during the course of your treatment with this drug, discuss the pros and cons with your doctor. Research has not shown if this drug passes into breast milk. In the event that you are breastfeeding, you should mention this to your doctor. It is also a good idea to ask your midwife for advice on other ways of feeding your infant until your course of treatment has finished.

This medication can cause anaphylaxis, a serious and life-threatening condition that requires prompt, emergency medical attention. If you develop a rash, have breathing difficulties, feel dizzy, develop swelling around your face, tongue, throat, face, or hands, within a few minutes of taking this drug, call 911 straight away.

While taking Terazosin, do not take any other prescription medication, over-the-counter medication, herbal remedies, or vitamin supplements, unless you have first discussed and cleared their use with your doctor.


Always keep your tablets or capsules in a sealed, airtight container, at room temperature. Do not place the medication in the fridge or freezer. Do not expose this drug to direct sunlight or to sources of extreme heat.

Keep Terazosin out of reach of children and pets. In the event that a pet consumes your medication, you should seek veterinary advice immediately.

Do not keep any leftover Terazosin or use a supply that has become out-of-date.

Do not flush unwanted medicine down the toilet or the drain. Do not throw any unused Terazosin tablets or capsules out with your garbage, where it could present a danger to small children and pets. Always ask your doctor or pharmacist for advice on the safe disposal of unwanted or unused medication.


Terazosin belongs to a group of drugs known as alpha blockers. These medications are used to treat high blood pressure (hypertension) and benign prostate enlargement. In the US, Terazosin is sold under the brand name, Hytrin.

Although there are not many recognised side-effects in people using this drug, it is not unusual for patients to begin to feel slightly dizzy when they first begin treatment. This problem often resolves itself within a couple of weeks of commencing taking this medication. There are also a large number of historical and existing medical conditions that can be made worse by the use of this drug. For this reason, you should always tell your doctor if you have a history of diabetes, liver or kidney disease, seizures, or heart conditions. The drug can cause drowsiness and problems in thinking clearly, which could be problematic for some patients in jobs that involve driving or operating machinery.

Terazosin has been shown to be very effective in the treatment and management of high blood pressure and benign prostate enlargement. In order to get the best results from your treatment with this drug, it is important that you attend regular check-ups with your doctor. These reviews will allow your doctor to determine the appropriate dose and frequency of use for this medication, and will give you the chance to mention any side-effects that you have noticed. You may also need to have blood and urine tests to check that the drug is working correctly, and your blood pressure will be closely monitored.

Last Reviewed:
December 23, 2017
Last Updated:
April 27, 2018
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