Doxazosin Side Effects

Brand Names: Cardura, Cardura XL

Please note - some side effects for Doxazosin may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA at http://www.fda.gov/medwatch/ or 1-800-FDA-1088 (1-800-332-1088).

Side Effects of Doxazosin - for the Consumer

Doxazosin

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Doxazosin:

Back pain; diarrhea; dizziness; drowsiness; dry mouth; feeling of a whirling motion; flu-like symptoms; headache; indigestion; lightheadedness; nasal congestion; nausea; pain; stomach pain; swelling; tiredness.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); blurred vision; chest pain; fainting; painful and prolonged penile erection; pounding in the chest; puffiness in hands or feet; swelling of eyelids.

Doxazosin Extended-Release Tablets

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Doxazosin Extended-Release Tablets:

Dizziness; drowsiness; headache; lightheadedness; stomach upset; weakness.

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); chest pain; fainting; fast or irregular heartbeat; painful or difficult urination; prolonged, painful erection; severe or prolonged dizziness or headache; shortness of breath.

Doxazosin Side Effects - for the Professional

Doxazosin

A. Benign Prostatic Hyperplasia:

The incidence of adverse events has been ascertained from worldwide clinical trials in 965 BPH patients. The incidence rates presented below (Table 3) are based on combined data from seven placebo-controlled trials involving once daily administration of Doxazosin mesylate in doses of 1-16 mg in hypertensives and 0.5-8 mg in normotensives. The adverse events when the incidence in the Doxazosin mesylate group was at least 1% are summarized in Table 3. No significant difference in the incidence of adverse events compared to placebo was seen except for dizziness, fatigue, hypotension, edema and dyspnea. Dizziness and dyspnea appeared to be dose-related.

In these placebo-controlled studies of 665 Doxazosin mesylate patients, treated for a mean of 85 days, additional adverse reactions have been reported. These are less than 1% and not distinguishable from those that occurred in the placebo group. Adverse reactions with an incidence of less than 1% but of clinical interest are (Doxazosin mesylate vs. placebo): Cardiovascular System: angina pectoris (0.6% vs. 0.7%), postural hypotension (0.3% vs. 0.3%), syncope (0.5% vs. 0.0%), tachycardia (0.9% vs. 0.0%); Urogenital System: dysuria (0.5% vs. 1.3%), and Psychiatric Disorders: libido decreased (0.8% vs. 0.3%). The safety profile in patients treated for up to three years was similar to that in the placebo-controlled studies.

The majority of adverse experiences with Doxazosin mesylate were mild.

B. Hypertension:

Doxazosin mesylate has been administered to approximately 4000 hypertensive patients, of whom 1679 were included in the hypertension clinical development program. In that program, minor adverse effects were frequent, but led to discontinuation of treatment in only 7% of patients. In placebo-controlled studies adverse effects occurred in 49% and 40% of patients in the Doxazosin and placebo groups, respectively, and led to discontinuation in 2% of patients in each group. The major reasons for discontinuation were postural effects (2%), edema, malaise/fatigue, and some heart rate disturbance, each about 0.7%.

In controlled hypertension clinical trials directly comparing Doxazosin mesylate to placebo there was no significant difference in the incidence of side effects, except for dizziness (including postural), weight gain, somnolence and fatigue/malaise. Postural effects and edema appeared to be dose related. The prevalence rates presented below are based on combined data from placebo-controlled studies involving once daily administration of Doxazosin at doses ranging from 1-16 mg. Table 4 summarizes those adverse experiences (possibly/probably related) reported for patients in these hypertension studies where the prevalence rate in the Doxazosin group was at least 0.5% or where the reaction is of particular interest.

Additional adverse reactions have been reported, but these are, in general, not distinguishable from symptoms that might have occurred in the absence of exposure to Doxazosin. The following adverse reactions occurred with a frequency of between 0.5% and 1%: syncope, hypoesthesia, increased sweating, agitation, increased weight. The following additional adverse reactions were reported by <0.5% of 3960 patients who received Doxazosin in controlled or open, short- or long- term clinical studies, including international studies. Cardiovascular System: angina pectoris, myocardial infarction, cerebrovascular accident; Autonomic Nervous System: pallor; Metabolic: thirst, gout, hypokalemia; Hematopoietic: lymphadenopathy, purpura; Reproductive System: breast pain; Skin Disorders: alopecia, dry skin, eczema; Central Nervous System: paresis, tremor, twitching, confusion, migraine, impaired concentration; Psychiatric: paroniria, amnesia, emotional lability, abnormal thinking, depersonalization; Special Senses: parosmia, earache, taste perversion, photophobia, abnormal lacrimation;  Gastrointestinal System: increased appetite, anorexia, fecal incontinence, gastroenteritis; Respiratory System: bronchospasm, sinusitis, coughing, pharyngitis; Urinary System: renal calculus; General Body System: hot flushes, back pain, infection, fever/rigors, decreased weight, influenza-like symptoms.

Doxazosin mesylate has not been associated with any clinically significant changes in routine biochemical tests. No clinically relevant adverse effects were noted on serum potassium, serum glucose, uric acid, blood urea nitrogen, creatinine or liver function tests. Doxazosin mesylate has been associated with decreases in white blood cell counts.

In post-marketing experience the following additional adverse reactions have been reported:

Autonomic Nervous System: priapism; Central Nervous System: hypoesthesia; Endocrine System: gynecomastia; Gastrointestinal System: vomiting; General Body System: allergic reaction; Heart Rate/Rhythm: bradycardia; Hematopoietic: leukopenia, thrombocytopenia; Liver/Biliary System: hepatitis, hepatitis cholestatic; Respiratory System: bronchospasm aggravated; Skin Disorders: urticaria; Urinary  System: hematuria, micturition disorder, micturition frequency, nocturia.

Side Effects by Body System

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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