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
Along with its needed effects, doxazosin may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor as soon as possible if any of the following side effects occur while taking doxazosin:More common
- Dizziness or lightheadedness
- Blurred vision
- dizziness, faintness, or lightheadedness when getting up from a lying or sitting position
- fainting (sudden)
- fast and pounding heartbeat
- irregular heartbeat
- shortness of breath
- swelling of feet or lower legs
- Painful or prolonged erection of the penis (called priapism), although extremely rare, must have immediate medical attention. If painful or prolonged erection occurs, call your doctor or go to an emergency room as soon as possible
- Abdominal or stomach pain
- area rash
- black, tarry stools
- bleeding gums
- blood in urine or stools
- chest pain or discomfort
- clay-colored stools
- dark urine
- difficulty breathing
- difficult, burning, or painful urination
- general tiredness and weakness
- headache, sudden and severe
- inability to speak
- lab results that show problems with liver
- light-colored stools
- loss of appetite
- noisy breathing
- pain or discomfort in arms, jaw, back or neck
- pinpoint red or purple spots on skin
- slow or irregular heartbeat
- slurred speech
- sore throat
- sores, ulcers, or white spots on lips or in mouth
- swollen glands
- temporary blindness
- tightness in chest
- unpleasant breath odor
- unusual bleeding or bruising
- upper right abdominal pain
- vomiting of blood
- weakness in arm and/or leg on one side of the body, sudden and severe
- yellow eyes and skin
Some side effects of doxazosin may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:More common
- lack or loss of strength
- unusual tiredness or weakness
- Acid or sour stomach
- back pain
- bladder pain
- cloudy urine
- difficulty in moving
- frequent urge to urinate
- joint pain
- lower back or side pain
- muscle aching, cramping, or weakness
- muscle pains or stiffness
- nervousness, restlessness, unusual irritability
- runny nose
- sleepiness or drowsiness
- sore throat
- stomach discomfort, upset or pain
- swollen joints
- burning, crawling, itching, numbness, prickling, “pins and needles”, or tingling feeling
- change in frequency or urination
- dry mouth
- feeling of warmth
- frequent urination
- general feeling of discomfort or illness
- hair loss
- hives or welts
- increased urge to urinate during the night
- increased volume of pale dilute urine
- loss of appetite
- painful urination
- redness of skin
- redness of the face, neck, arms and occasionally upper chest
- swelling of the breasts or breast soreness in both females and males
- thinning of hair
- trouble in holding or releasing urine
- trouble sleeping
- waking to urinate at night
- weight loss
For Healthcare Professionals
Applies to doxazosin: oral tablet, oral tablet extended release
Doxazosin is generally well-tolerated. Side effects are usually mild to moderate in intensity and may resolve with continued therapy.
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.
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.
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 system complaints of dyspnea and rhinitis have been reported in 3% to 4% of patients. Aggravated bronchospasm has been reported in postmarketing studies.
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 pain has been reported in 1% to 5% of patients. Muscle cramps and muscle weakness have been reported in postmarketing studies.
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 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 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.
From a study of 1,548 patients, less than 2% reported a rash.
Hypersensitivity to doxazosin has been rarely reported.
Hepatic side effects including abnormal liver function tests, hepatitis, cholestatic hepatitis, and jaundice have been reported in postmarketing studies.
Dermatologic side effects have included urticaria. Alopecia has been reported in postmarketing studies.
Other side effects including fatigue, hot flashes, and malaise have been reported in postmarketing studies.
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