Doxazosin Side Effects

Some side effects of doxazosin may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

For the Consumer

Applies to doxazosin: oral tablet, oral tablet extended release

Get emergency medical help if you have any of these signs of an allergic reaction while taking doxazosin: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have a serious side effect such as:

• feeling like you might pass out;

• fast or pounding heartbeats, fluttering in your chest;

• trouble breathing;

• swelling in your hands, ankles, or feet; or

• penis erection that is painful or lasts 4 hours or longer.

Less serious side effects of doxazosin may include:

• mild dizziness;

• tired feeling, drowsiness;

• headache;

• nausea; or

• runny nose.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.

For Healthcare Professionals

Applies to doxazosin: oral tablet, oral tablet extended release

General

Doxazosin is generally well-tolerated. Side effects are usually mild to moderate in intensity and may resolve with continued therapy.

Cardiovascular

Like other alpha-blockers, doxazosin has been associated with significant decreases in total and LDL serum cholesterol and serum triglycerides. This beneficial effect on the lipid profile may be important in some patients with ischemic heart disease.

Data from ALLHAT (which led to the discontinuation of the doxazosin-treatment arm of the study) indicated that users of doxazosin had 25% more cardiovascular events and were twice as likely to be hospitalized for congestive heart failure compared to users of chlorthalidone. However, these two drugs were found to be similarly effective in preventing heart attacks and in reducing the risk of death from all causes.

Cardiovascular side effects are the most common. Dizziness has been reported in 3% to 14% of patients and is most likely to occur 2 to 6 hours after dosing. It may be minimized by administration of the drug at bedtime, particularly at the beginning of therapy. Rarely, syncope has been associated with doxazosin, and appears to be more likely in patients greater than 65 years old. Peripheral edema, palpitations, chest pain, and tachycardia have been reported in 7%, 4%, 3%, and 2% of patients, respectively.

Cerebrovascular accidents, postural dizziness, bradycardia, cardiac arrhythmias, and myocardial infarction have been reported in postmarketing studies.

Patients treated with doxazosin during the Antihypertensive and Lipid Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) had a greater likelihood of developing congestive heart failure.

Ocular

Most reports were in patients treated with an alpha-1 blocker at the time IFIS occurred, but in some instances the alpha-1 blocker had been stopped prior to surgery. The manufacturer recommends that patients be questioned to determine whether or not they have taken alpha-1 blockers prior to being considered for cataract surgery. If it is determined that the patient has taken an alpha-1 blocker, the patient's ophthalmologist should be prepared for possible modifications to their surgical technique that may be necessary should IFIS be observed during the procedure.

Ocular side effects including Intraoperative Floppy Iris Syndrome (IFIS) have been observed in some patients undergoing phacoemulsification cataract surgery while being treated with alpha-1 blockers.

Blurred vision has been reported in postmarketing studies.

Nervous system

Anxiety, insomnia, and paresthesias have each been reported in 2% of patients. Dry mouth and flushing have been reported in less than 2% of patients.

Nervous system side effects have included dizziness in up to 17%, headache or fatigue/lethargy in 10% to 15%, and somnolence in 5% of patients. Hypoesthesia and paresthesia have been reported in postmarketing studies.

Respiratory

Respiratory system complaints of dyspnea and rhinitis have been reported in 3% to 4% of patients. Aggravated bronchospasm has been reported in postmarketing studies.

Gastrointestinal

Gastrointestinal side effects are unusual, and are mainly limited to nausea or diarrhea in 1% to 3% of patients.

Dyspepsia, general abdominal pain, flatulence, and constipation have each been reported in about 1% of patients.

Musculoskeletal

Musculoskeletal pain has been reported in 1% to 5% of patients. Muscle cramps and muscle weakness have been reported in postmarketing studies.

Genitourinary

Genitourinary complaints are rare. Approximately 3% of men have reported impotence and about 1% have reported urinary frequency. Hematuria, micturition disorder, micturition frequency, nocturia, polyuria, and gynecomastia have been reported in postmarketing studies. In addition, at lease one case of priapism associated with doxazosin use has been reported.

The Treatment of Mild Hypertension Study (TOMHS), a randomized, placebo-controlled, double-blind study has shown that there is a slightly and significantly higher incidence of sexual dysfunction (obtaining and maintaining erections) among male patients who were taking doxazosin for 48 months compared with placebo

Psychiatric

Psychiatric abnormalities including depression and anxiety have been reported in less than 2% of patients. Anorexia and nervousness have been reported in postmarketing studies. In addition, at least one case of psychosis associated with doxazosin use has been reported.

In a study of 23 hypertensive patients with renal insufficiency, a single case of a personality change has been associated with the use of doxazosin.

Hematologic

Hematologic abnormalities are extremely rare. Decreases in baseline white blood cell and neutrophil counts of 2.4% and 1.0%, respectively, have been reported from controlled clinical trials. Leukopenia, purpura, and thrombocytopenia have been reported in postmarketing studies.

The manufacturer has reported 4 possible doxazosin-related cases of neutropenia from a database of 2,400 patients. In cases where follow-up was available the white blood cell count and differential cell count returned to normal after drug discontinuation. No patients became symptomatic as a result of the low white blood cell or neutrophil counts.

Hypersensitivity

From a study of 1,548 patients, less than 2% reported a rash.

Hypersensitivity to doxazosin has been rarely reported.

Hepatic

Hepatic side effects including abnormal liver function tests, hepatitis, cholestatic hepatitis, and jaundice have been reported in postmarketing studies.

Dermatologic

Dermatologic side effects have included urticaria. Alopecia has been reported in postmarketing studies.

Other

Other side effects including fatigue, hot flashes, and malaise have been reported in postmarketing studies.

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