Terazosin is in a group of drugs called alpha-adrenergic blockers. Terazosin relaxes your veins and arteries so that blood can more easily pass through them. It also relaxes the muscles in the prostate and bladder neck, making it easier to urinate.
Terazosin is used to treat hypertension (high blood pressure), or to improve urination in men with benign prostatic hyperplasia (enlarged prostate).
Terazosin may also be used for other purposes not listed in this medication guide.
Important information
Terazosin may cause dizziness or fainting, especially when you first start taking it or when you start taking it again. You may wish to take this medication only at bedtime if it causes you to feel light-headed. Be careful if you drive or do anything that requires you to be alert. Avoid standing for long periods of time or becoming overheated during exercise and in hot weather. Avoid getting up too fast from a sitting or lying position, or you may feel dizzy.
You should not use this medication if you are allergic to terazosin.
If you stop taking terazosin for any reason, call your doctor before you start taking it again. You may need a dose adjustment.
Terazosin can affect your pupils during cataract surgery. Tell your eye surgeon ahead of time that you are using terazosin. Do not stop using terazosin before surgery unless your surgeon tells you to.
Tell your doctor about all other medications you use, especially other blood pressure medications including diuretics (water pills).
Before taking this medicine
You should not use this medication if you are allergic to terazosin.
If you have a history of prostate cancer, you may need a dose adjustment or special tests to safely take terazosin.
Terazosin can affect your pupils during cataract surgery. Tell your eye surgeon ahead of time that you are using this medication. Do not stop using terazosin before surgery unless your surgeon tells you to.
FDA pregnancy category C. It is not known whether terazosin will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using this medication. It is not known whether terazosin passes into breast milk or if it could harm a nursing baby. Do not use terazosin without telling your doctor if you are breast-feeding a baby.
See also: Pregnancy and breastfeeding warnings (in more detail)
How should I take terazosin?
Take terazosin exactly as prescribed by your doctor. Do not take in larger or smaller amounts or for longer than recommended. Follow the directions on your prescription label.
Your doctor may occasionally change your terazosin dose to make sure you get the best results.
Terazosin lowers blood pressure and may cause dizziness or fainting, especially when you first start taking it, or when you start taking it again. You may wish to take this medication only at bedtime if it causes you to feel light-headed. Call your doctor if you have severe dizziness or feel like you might pass out.
You may feel very dizzy when you first wake up. Be careful when standing or sitting up from a lying position.
If you stop taking terazosin for any reason, call your doctor before you start taking it again. You may need a dose adjustment.
Your blood pressure or prostate will need to be checked often. Visit your doctor regularly.
If you are being treated for high blood pressure, keep using terazosin even if you feel well. High blood pressure often has no symptoms. You may need to use blood pressure medication for the rest of your life.
Some things can cause your blood pressure to get too low. This includes vomiting, diarrhea, heavy sweating, heart disease, dialysis, a low-salt diet, or taking diuretics (water pills). Tell your doctor if you have a prolonged illness that causes diarrhea or vomiting.
Store terazosin at room temperature away from moisture, heat, and light.
What happens if I miss a dose?
Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.
If you miss your doses for several days in a row, contact your doctor before restarting the medication. You may need a lower dose.
What happens if I overdose?
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.
Overdose symptoms may include extreme dizziness or fainting.
What should I avoid?
Terazosin may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert.
To prevent dizziness, avoid standing for long periods of time or becoming overheated during exercise and in hot weather.
Avoid getting up too fast from a sitting or lying position, or you may feel dizzy. Get up slowly and steady yourself to prevent a fall. Drinking alcohol can increase certain side effects of terazosin.
Terazosin side effects
Get emergency medical help if you have any of these signs of an allergic reaction to terazosin: hives; difficulty breathing; swelling of your face, lips, tongue, or throat. Call your doctor at once if you have any of these serious side effects:
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fast or pounding heartbeats or fluttering in your chest;
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feeling like you might pass out;
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swelling in your hands, ankles, or feet; or
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penis erection that is painful or lasts 4 hours or longer.
Less serious terazosin side effects may include:
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mild dizziness;
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weakness, drowsiness;
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blurred vision;
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nausea; or
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headache.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
See also: Side effects (in more detail)
Terazosin dosing information
Usual Adult Dose for Hypertension:
Initial dose: 1 mg orally once a day at bedtime
Maintenance dose: 1-5 mg orally once a day.
Maximum dose: 20 mg per day.
Usual Adult Dose for Benign Prostatic Hyperplasia:
Initial dose: 1 mg orally once a day at bedtime.
Maintenance dose: Increased in a stepwise fashion to 2 mg, 5 mg, or 10 mg once a day to achieve desired improvement of symptoms.
What other drugs will affect terazosin?
Tell your doctor about all other medications you use, especially:
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sildenafil (Viagra, Revatio);
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tadalafil (Cialis);
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vardenafil (Levitra);
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verapamil (Calan, Covera, Isoptin, Verelan); or
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other blood pressure medications, including diuretics (water pills).
This list is not complete and other drugs may interact with terazosin. Tell your doctor about all medications you use. This includes prescription, over-the-counter, vitamin, and herbal products. Do not start a new medication without telling your doctor.
