- Type of Drug: Alpha blocker.
- Prescribed for: High blood pressure; urinary symptoms of benign prostatic hypertrophy (BPH) in men.
Terazosin (Hytrin) General Information
Terazosin lowers blood pressure by opening blood vessels and reducing pressure within them. Terazosin and similar drugs block nerve endings known as alpha 1 receptors. Other blood-pressure-lowering drugs block beta receptors, interfere with the movement of calcium in blood-vessel muscle cells, affect salt and electrolyte balance in the body, or interfere with the process for manufacturing norepinephrine. The maximum blood-pressure-lowering effect of Terazosin is seen between 2 and 6 hours after taking a single dose. Terazosin’s effect lasts for 24 hours. In BPH, Terazosin works by relaxing smooth muscles in the prostate and neck of the bladder. Here, too, this effect is produced by blockade of alpha receptors in the affected muscles. Despite the fact that Terazosin reduces the symptoms of BPH, the drug’s long-term effect on complications of BPH or the need for urinary surgery is not known. Age and race have no effect on response. Alpha blockers are broken down in the liver and/or pass out of the body through the feces. About 40 percent of Terazosin passes out of the body via the kidneys.
Terazosin (Hytrin) Cautions and Warnings
Terazosin can cause dizziness and fainting, especially with the first few doses. This is known as the first-dose effect. This effect can be minimized by limiting the first dose to 1 mg at bedtime. The first-dose effect occurs in about 1 percent of people taking an alpha blocker and can recur if the drug is stopped for a few days and then restarted.
People who are allergic or sensitive to any of the alpha blockers should avoid the others because of the chance that they will react to them as well.
Terazosin may slightly reduce cholesterol levels and increase the HDL/LPL (important blood fats) ratio, a positive step for people with a blood-cholesterol problem. People with an already high blood-cholesterol level should discuss this situation with their doctors.
Red- and white-blood-cell counts may be slightly decreased in people taking Terazosin,
People taking Terazosin may gain a small amount of weight (about 2 pounds).
Terazosin (Hytrin) Possible Side Effects
- Most common: dizziness, weakness, and headache.
- Less common: dizziness when rising from a sitting or lying position; low blood pressure; rapid heartbeat; abnormal heart rhythms; chest pain; flushing in the face, arms, or legs; fainting; vomiting; dry mouth; diarrhea; constipation; abnormal heart rhythms; chest pain; flushing in the face, arms, or legs; fainting; vomiting; dry mouth; diarrhea; constipation; abdominal pain or discomfort; stomach gas; breathing difficulty; stuffy nose; sinus inflammation; cold or flu symptoms; cough; bronchitis; worsening of asthma; nosebleeds; sore throat; runny nose; shoulder, neck, or back pain; pain in the arms or legs; joint pains; arthritis; muscle pain, blurring or other visual disturbances; conjunctivitis (“pink-eye”); eye pain; nervousness; tingling in the hands or feet; tiredness; anxiety; trouble sleeping; frequent urination; urinary infection; itching; rash; sweating; swelling of the face, arms, or legs; and fever.
- Rare: depression, reduced sex drive or abnormal sexual function, fluid retention, and weight gain.
- Terazosin may interact with beta-blocking drugs to produce a higher rate of dizziness or fainting after taking the first dose of Terazosin.
- The blood-pressure-lowering effect of Terazosin may be reduced by Indomethacin.
- When taken with other blood-pressure-lowering drugs, Terazosin produces an exaggerated reduction of blood pressure.
- The blood-pressure-lowering effect of Clonidine may be reduced by Terazosin.
- This drug does not affect the results of the prostate- specific antigen (PSA) test often used to monitor the progress of BPH.
Terazosin may be taken without regard to food or meals.
Terazosin (Hytrin) Usual Dose
The usual starting dose of Terazosin is 1 mg at bedtime. The dosage may be increased in 1- to 5-mg increments to a total of 20 to 40 mg per day. Terazosin may be taken once or twice a day. Doses of 10 mg once a day are generally needed to control the symptoms of BPH.
Terazosin overdose may produce drowsiness, poor reflexes, and very low blood pressure. Overdose victims should be taken to a hospital emergency room at once. ALWAYS bring the prescription bottle.
Terazosin (Hytrin) Special Information
Take this drug exactly as prescribed, and do not stop taking it unless directed to do so by your doctor. Avoid nonprescription drugs that contain stimulants because they can increase your blood pressure. Your pharmacist will be able to tell you what you “can and cannot take.
Terazosin can causer dizziness, headache, and drowsiness, especially 2 to 6 hours after you take your first drug dose, although these effects can persist after the first few doses.
Call your doctor if you develop severe dizziness, heart palpitations* or other bothersome or persistent side effects.
Wait 12 to 24 hours after taking the first dose before driving or doing anything that requires intense concentration. You should take it at bedtime to minimize this problem.
If you forget to take a dose of Terazosin and you take it once a day, take it as soon as you remember. If you take it twice a day and it is almost time for your next dose, skip the forgotten dose and continue with your regular medication schedule. Taking your medicine at the same time each day will help you to remember your medicine.
Animal studies of large doses of Terazosin in animals showed an effect on developing fetuses, but the effect of Terazosin in pregnant women is not known. It should be used only when its benefits clearly outweigh its potential dangers.
It is not known if Terazosin passes into breast milk. Nursing mothers who must take this medication should bottle-feed their babies.
Older adults may be more sensitive to the effects and side effects of Terazosin. Report any unusual side effects to your doctor.