Commonly reported side effects of zidovudine include: headache, nausea, neutropenia, vomiting, anemia, anorexia, and malaise. See below for a comprehensive list of adverse effects.

Applies to zidovudine: oral capsule, oral syrup, oral tablet

Other dosage forms:

• intravenous solution

Along with its needed effects, zidovudine 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 immediately if any of the following side effects occur while taking zidovudine:

More common

• Black, tarry stools
• chills
• cough
• feeling of fullness
• fever
• lower back or side pain
• painful or difficult urination
• pale skin
• right upper abdominal pain and fullness
• sore throat
• stomach pain
• swelling or inflammation of the mouth
• swollen lymph nodes
• ulcers, sores, or white spots in the mouth
• unusual bleeding or bruising
• unusual tiredness or weakness

Rare

• Confusion
• diarrhea
• fast, shallow breathing
• general feeling of discomfort
• loss of appetite
• mood or mental changes
• muscle pain, tenderness, weakness, or cramping
• nausea
• seizures
• sleepiness
• stomach discomfort

Incidence not known

• Back or leg pain
• bleeding gums
• blistering, peeling, or loosening of the skin
• bloating
• blood in the urine
• blurred vision or other change in vision
• bone pain
• burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
• clay-colored stools
• constipation
• dark urine
• decreased appetite
• decreased urine output
• difficult or labored breathing
• difficulty in moving
• difficulty in swallowing
• dilated neck veins
• dizziness
• extreme tiredness or weakness
• fainting
• fast, irregular, or pounding heartbeat
• general body swelling
• general tiredness and weakness
• headache
• high fever
• hives, skin rash
• hoarseness
• increased need to urinate
• indigestion
• irregular breathing
• irritation or soreness of the mouth
• joint or muscle pain
• lack of coordination
• large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or genitals
• light-colored stools
• muscle pain, cramp, spasm, or stiffness
• nosebleeds
• pains in the stomach, side, or abdomen, possibly radiating to the back
• passing urine more often
• puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
• red skin lesions, often with a purple center
• red, irritated eyes
• redness, soreness, or itching skin
• runny nose
• shakiness in the legs, arms, hands, or feet
• shivering
• sores, welts, or blisters
• stabbing pain
• sweating
• swollen joints
• swollen or painful glands
• tightness in the chest
• trouble sleeping
• unexplained bleeding or bruising
• unpleasant breath odor
• vomiting
• vomiting of blood
• weight gain
• yellow eyes or skin

Some side effects of zidovudine 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

• Difficulty having a bowel movement
• headache (severe)
• lack or loss of strength
• muscle soreness
• weight loss

Less common

• Bluish-brown colored bands on nails
• changes in skin color

Incidence not known

• Belching
• heartburn
• stomach cramps

Applies to zidovudine: intravenous solution, oral capsule, oral syrup, oral tablet

The most common side effects reported during adult clinical trials were headache, malaise, nausea, anorexia, and vomiting; side effects reported most often with IV administration were anemia and neutropenia. The most common side effects reported during pediatric clinical trials were fever and cough. In the prevention of maternal-fetal transmission clinical trial, the most common side effects reported in neonates were anemia and neutropenia.

Hematologic toxicity (including neutropenia and severe anemia) has been reported, mostly in patients with advanced HIV-1 disease.

Exacerbation of anemia due to ribavirin has been reported when this drug was part of the HIV-1 regimen.

Common (1% to 10%): Granulocytopenia (less than 750 cells/mm3)

Uncommon (0.1% to 1%): Anemia (hemoglobin less than 8 g/dL)

Frequency not reported: Neutropenia, hematologic toxicity/bone marrow suppression, exacerbation of anemia, increased hemoglobin A2 percentage, thrombocytopenia, macrocytosis

Postmarketing reports: Aplastic anemia, hemolytic anemia, leukopenia, lymphadenopathy, pancytopenia with marrow hypoplasia, pure red cell aplasia

Very common (10% or more): Headache (up to 63%)

Common (1% to 10%): Neuropathy

Frequency not reported: Decreased reflexes, hyperalgesia, numbness, status epilepticus, Wernicke's syndrome

Postmarketing reports: Seizures, dizziness, paresthesia, somnolence, vertigo, hearing loss, loss of mental acuity, syncope, taste perversion, tremor

In 1 case of drug-associated fever, no source of infection was found after an extensive evaluation, but an anti-zidovudine immunoglobulin was isolated, indicating a possible hypersensitivity reaction.

This drug has been associated with lower levels of vitamins B2 and C, folate, and zinc despite adequate dietary intake.

Very common (10% or more): Malaise (up to 53%)

Common (1% to 10%): Asthenia, fatigue, chills

Frequency not reported: Fever, signs/symptoms of ears (included pain, discharge, erythema, swelling of ear), edema, weight loss, rigors, increased lactate dehydrogenase, lower levels of vitamins B2/C/folate/zinc

Postmarketing reports: Chest pain, influenza-like syndrome, generalized pain

Antiretroviral therapy:

-Frequency not reported: Increased weight

Very common (10% or more): Nausea (up to 51%), vomiting (up to 17%)

Common (1% to 10%): Constipation, dyspepsia, abdominal cramps, abdominal pain, gastrointestinal pain

Frequency not reported: Diarrhea, stomatitis, splenomegaly, elevated lipase, elevated total amylase, lip edema, tongue edema, eructation, bleeding gums, rectal hemorrhage

Postmarketing reports: Dysphagia, constipation, flatulence, oral mucosa pigmentation, mouth ulcer, pancreatitis

Lactic acidosis and severe hepatomegaly with steatosis (including fatal cases) have been reported with the use of nucleoside analogs.

Very common (10% or more): Anorexia (up to 20%)

Rare (0.01% to 0.1%): Lactic acidosis without hypoxemia

Frequency not reported: Hyperlipidemia

Postmarketing reports: Redistribution/accumulation of body fat, lactic acidosis, hyperlactatemia

Antiretroviral therapy:

-Frequency not reported: Increased blood lipid levels, increased glucose levels

A patient with preexisting hepatitis B developed acute hepatic failure 2 weeks after starting this drug.

Lactic acidosis and severe hepatomegaly with steatosis (including fatal cases) have been reported with the use of nucleoside analogs.

Hepatic decompensation (some fatal) has been reported in patients coinfected with HIV-1 and hepatitis C receiving combination antiretroviral therapy for HIV-1 and interferon alfa with or without ribavirin.

Common (1% to 10%): Elevated ALT (greater than 5 times the upper limit of normal [5 x ULN]), raised blood levels of liver enzymes and bilirubin

Uncommon (0.1% to 1%): Elevated AST (greater than 5 x ULN), hyperbilirubinemia

Rare (0.01% to 0.1%): Liver disorders (e.g., severe hepatomegaly with steatosis)

Frequency not reported: Fulminate hepatitis, hepatic failure, hepatomegaly, hepatic decompensation, changes in liver function tests

Postmarketing reports: Hepatitis, hepatomegaly with steatosis, jaundice

Myopathy, myositis, muscle tenderness, and weakness in the arms and legs have been reported and were generally associated with an elevation in serum creatine kinase.

In 1 study, myalgias and elevated creatine kinase occurred in 8% of treated patients with a CD4 cell count less than 200/mm3, and in none of the patients with higher CD4 cell counts. Dose reduction has not affected the course of myopathy, although drug discontinuation sometimes resulted in improvement of symptoms, generally within a month. Muscle biopsy has shown atrophic and sometimes necrotic fibers, ragged-red fibers, and large accumulations of mitochondrial and fibrillar sarcoplasmic inclusions.

Myopathy and myositis with pathological changes, similar to that produced by HIV-1 disease, have been associated with prolonged use of this drug.

Common (1% to 10%): Arthralgia, myalgia, musculoskeletal pain

Frequency not reported: Myopathy, myositis, muscle tenderness, weakness in the arms and legs, osteonecrosis, twitch

Postmarketing reports: Increased creatine phosphokinase, muscle spasm, myopathy and myositis with pathological changes (similar to that produced by HIV-1 disease), rhabdomyolysis, back pain

Common (1% to 10%): Insomnia

Frequency not reported: Nervousness/irritability, emotional lability, grandiosity

Postmarketing reports: Anxiety, confusion, depression, mania

Bluish or brownish-black discoloration of nails has developed during the first month or 2 of therapy and usually disappeared within 2 months if the drug was discontinued. Discoloration has occurred as longitudinal streaks or transverse bands.

Frequency not reported: Skin rashes, lipoatrophy/loss of subcutaneous fat, body odor, acne, nailbed hyperpigmentation (rarely accompanied by mucocutaneous pigmentation or hypertrichosis), leukocytoclastic vasculitis (with eosinophilia and fever)

Postmarketing reports: Changes in skin and nail pigmentation, pruritus, Stevens-Johnson syndrome, toxic epidermal necrolysis, sweat, urticaria

Frequency not reported: Congestive heart failure ECG abnormality, left ventricular dilation, vasodilation

Postmarketing reports: Cardiomyopathy, vasculitis

Frequency not reported: Allergic skin rash

Postmarketing reports: Sensitization reactions (including anaphylaxis, angioedema)

Frequency not reported: Cough, abnormal breath sounds/wheezing, nasal discharge/congestions, flu syndrome, epistaxis, pharyngitis, hoarseness

Postmarketing reports: Dyspnea, rhinitis, sinusitis

Frequency not reported: Immune reconstitution/reactivation syndrome, autoimmune disorders in the setting of immune reconstitution (e.g., Graves' disease, polymyositis, Guillain-Barre syndrome)

A case of macular edema in a patient with a history of anterior uveitis secondary to syphilis has been reported.

Postmarketing reports: Amblyopia, macular edema, photophobia

Frequency not reported: Hematuria, dysuria, polyuria

Postmarketing reports: Urinary frequency, urinary hesitancy

Postmarketing reports: Gynecomastia

Local reaction, pain, and slight irritation were reported infrequently during IV administration.

Frequency not reported: Local reaction, pain, slight irritation