terazosin, Hytrin

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GENERIC NAME: terazosin


DRUG CLASS AND MECHANISM: Terazosin belongs to a class of medications called alpha 1 blockers which relax the smooth muscles of the arteries, the prostate, and the bladder neck. Other alpha blockers include doxazosin (Cardura), alfuzosin (Uroxatral), tamsulosin (Flomax), and prazosin (Minipress). Relaxing the smooth muscles of the arteries lowers blood pressure. Relaxing the smooth muscles around the bladder neck relieves urinary obstruction caused by an enlarged prostate (prostate hypertrophy). Terazosin relaxes the smooth muscles of the bladder neck and the prostate, increasing urine flow. The FDA approved terazosin in 1987.



PREPARATIONS: Tablets or Capsules: 1, 2, 5, and 10 mg.

STORAGE: Terazosin should be stored at room temperature below 86 F (30 C) in a tight container.

PRESCRIBED FOR: Terazosin is used to treat the symptoms of urinary obstruction due to an enlarged prostate caused by benign prostatic hypertrophy (BPH). Terazosin also is used alone or in combination with another blood pressure medication to treat high blood pressure.

DOSING: Terazosin may be taken with or without food. The recommended starting dose for treating BPH is 1 mg daily. The dose should be increased in a stepwise fashion up to 10 mg daily which is the effective dose for most patients. Some patients may show additional improvement with a 20 mg dose. For high blood pressure the recommended dose is 1 to 5 mg once daily. Some patients may benefit from doses as high as 20 mg per day. Terazosin also may be administered twice daily.

DRUG INTERACTIONS: PDE-5 inhibitors used primarily for erectile dysfunction (for example, vardenafil [Levitra, Staxyn], Adcirca, tadalafil [Cialis], sildenafil [Viagra, Revatio) add to the blood pressure lowering effects of terazosin and may result in orthostatic or postural hypotension. (See Side Effects.) Individuals who take terazosin should be on a stable dose before a PDE-5 inhibitor is started, and the PDE-5 inhibitor should be started at the lowest dose. If the patient is already taking a PDE-5 inhibitor terazosin should be started at the lowest dose.

PREGNANCY: There are no adequate studies of terazosin in pregnancy. It is not recommended during pregnancy unless the benefits justify the potential but unknown risks to the fetus

NURSING MOTHERS: It is not known whether terazosin is excreted in breast milk.

SIDE EFFECTS: Besides postural hypotension and dizziness, side effects include weakness, fatigue, headaches, swelling of the legs (edema), palpitations, nasal congestion, sleepiness, decreased libido, impotence, and blurred vision. By relaxing the smooth muscles and dilating the arteries, terazosin can cause a marked lowering of the blood pressure especially when the patient stands up (orthostatic or postural hypotension). Postural hypotension can cause the patient to faint upon standing. Postural hypotension and fainting usually are associated with the first dose or the first few days of treatment. Hypotension and fainting also can occur when doses of medication are increased abruptly or another blood pressure medication is added. In order to decrease the likelihood of excessive hypotension and fainting, terazosin is initiated low doses. Prostate cancer and prostatic hypertrophy both cause similar symptoms of obstruction to the flow of urine. Prostate cancer and prostatic hypertrophy can co-exist. Therefore, patients being treated for prostate hypertrophy should be evaluated to exclude the presence of prostate cancer.

Reference: FDA Prescribing Information

Last Editorial Review: 3/2/2012

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