Doxazosin Side Effects

Medically reviewed by Drugs.com. Last updated on Mar 31, 2025.

Applies to doxazosin: oral tablet, oral tablet extended release.

Serious side effects of doxazosin

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 side effects

• dizziness or lightheadedness

Less common side effects

• blurred vision
• confusion
• dizziness, faintness, or lightheadedness when getting up from a lying or sitting position
• fainting (sudden)
• fast and pounding heartbeat
• irregular heartbeat
• shortness of breath
• sweating
• swelling of feet or lower legs

Rare side effects

• 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

Incidence not known

• abdominal or stomach pain
• area rash
• black, tarry stools
• bleeding gums
• blood in urine or stools
• chest pain or discomfort
• chills
• clay-colored stools
• cough
• dark urine
• diarrhea
• difficulty breathing
• difficult, burning, or painful urination
• fever
• general tiredness and weakness
• headache, sudden and severe
• inability to speak
• itching
• 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
• rash
• seizures
• 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
• vomiting of blood
• weakness in arm and/or leg on one side of the body, sudden and severe
• wheezing
• yellow eyes and skin

Other side effects of doxazosin

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 side effects

• headache
• lack or loss of strength
• unusual tiredness or weakness

Less common side effects

• acid or sour stomach
• back pain
• belching
• bladder pain
• cloudy urine
• difficulty in moving
• frequent urge to urinate
• heartburn
• indigestion
• joint pain
• lower back or side pain
• muscle aching, cramping, or weakness
• muscle pains or stiffness
• nausea
• nervousness, restlessness, unusual irritability
• runny nose
• sleepiness or drowsiness
• sneezing
• sore throat
• stomach discomfort, upset or pain
• swollen joints

Incidence not known

• anxiety
• 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
• hyperventilation
• 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
• shaking
• 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.

General adverse events

The most common adverse reaction was dizziness.^[Ref]

Nervous system

• Very common (10% or more): Dizziness (up to 19%)
• Common (1% to 10%): Somnolence, headache, vertigo
• Uncommon (0.1% to 1%): Cerebrovascular accident, hypoesthesia, syncope, tremor, tinnitus
• Very rare (less than 0.01%): Dizziness postural, paresthesia
• Frequency not reported: Taste disturbance^[Ref]

Other

• Very common (10% or more): Fatigue/malaise (12%)
• Common (1% to 10%): Asthenia, chest pain, influenza-like symptoms
• Uncommon (0.1% to 1%): Pain, facial edema^[Ref]

Respiratory

• Common (1% to 10%): Dyspnea, rhinitis, respiratory tract infection, bronchitis, cough
• Uncommon (0.1% to 1%): Epistaxis
• Very rare (less than 0.01%): Bronchospasm
• Postmarketing reports: Bronchospasm aggravated^[Ref]

Gastrointestinal

• Common (1% to 10%): Dry mouth, abdominal pain, dyspepsia, nausea
• Uncommon (0.1% to 1%): Constipation, flatulence, vomiting, gastroenteritis, diarrhea
• Frequency not reported: Gastrointestinal obstruction^[Ref]

Genitourinary

• Common (1% to 10%): Polyuria, urinary tract infection, cystitis, urinary incontinence
• Uncommon (0.1% to 1%): Dysuria, micturition frequency, hematuria, impotence
• Very rare (less than 0.01%): Micturition disorder, nocturia, priapism
• Frequency not reported: Retrograde ejaculation^[Ref]

Cardiovascular

• Common (1% to 10%): Hypotension, postural hypotension, palpitation, tachycardia
• Uncommon (0.1% to 1%): Angina pectoris, myocardial infarction
• Very rare (less than 0.01%): Bradycardia, cardiac arrhythmias, hot flushes^[Ref]

Metabolic

• Common (1% to 10%): Edema, peripheral edema
• Uncommon (0.1% to 1%): Gout, appetite increased, anorexia, weight increased^[Ref]

Musculoskeletal

• Common (1% to 10%): Myalgia, back pain
• Uncommon (0.1% to 1%): Arthralgia
• Rare (less than 0.1%): Muscle cramps, muscle weakness^[Ref]

Dermatologic

• Common (1% to 10%): Pruritus
• Uncommon (0.1% to 1%): Skin rash
• Very rare (less than 0.01%): Urticaria, purpura, alopecia^[Ref]

Psychiatric

• Uncommon (0.1% to 1%): Agitation, depression, anxiety, insomnia, nervousness
• Frequency not reported: Libido decreased^[Ref]

Hepatic

• Uncommon (0.1% to 1%): Abnormal liver function tests
• Very rare (less than 0.01%): Cholestasis, hepatitis, jaundice
• Postmarketing reports: Hepatitis cholestatic^[Ref]

Immunologic

• Uncommon (0.1% to 1%): Allergic drug reaction
• Postmarketing reports: Allergic reaction^[Ref]

Hematologic

• Very rare (less than 0.01%): Leukopenia, thrombocytopenia
• Frequency not reported: White blood cell counts decreased, neutrophil count decreased^[Ref]

Ocular

• Very rare (less than 0.01%): Blurred vision
• Frequency not reported: Intraoperative Floppy Iris Syndrome (IFIS)^[Ref]

Endocrine

• Very rare (less than 0.01%): Gynecomastia^[Ref]

Renal

• Very rare (less than 0.01%): Diuresis increased^[Ref]

Further information

Doxazosin side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

Medical Disclaimer