Allopurinol Side Effects
Some side effects of allopurinol 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 allopurinol: oral tablet
Get emergency medical help if you have any of these signs of an allergic reaction while taking allopurinol: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Stop using allopurinol and call your doctor at once if you have a serious side effect such as:
fever, sore throat, and headache with a severe blistering, peeling, and red skin rash;
the first sign of any skin rash, no matter how mild;
pain or bleeding when you urinate;
nausea, upper stomach pain, itching, loss of appetite, weight loss, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes);
urinating less than usual or not at all;
joint pain, flu symptoms;
severe tingling, numbness, pain, muscle weakness; or
easy bruising, unusual bleeding (nose, mouth, vagina, or rectum), purple or red pinpoint spots under your skin.
Less serious side effects of allopurinol may include:
changes in your sense of taste; or
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 allopurinol: intravenous powder for injection, oral tablet
In general, the side effects of allopurinol have been more likely and more severe in patients with reduced renal function.
Allopurinol-induced rash may be followed by more severe hypersensitivity reactions, including Stevens-Johnson syndrome, toxic epidermal necrolysis, vasculitis, nephrotoxicity, and hepatotoxicity. Such hypersensitivity syndromes have been fatal in some cases.
The incidence of skin rash may be increased in patients with renal dysfunction.
Dermatologic side effects have included skin rash, pruritus, and alopecia. Severe skin reactions have rarely included exfoliative dermatitis, vesicular bullous eruptions, and erythema multiforme.
A case study suggests cell-mediated immunity to allopurinol and oxypurinol is involved in allopurinol-induced hypersensitivity reactions.
A first of a kind case report, allopurinol hypersensitivity syndrome, elevations in pancreatic exocrine enzyme level, and new-onset type 1 diabetes mellitus have been reported in a 58-year-old Cambodian female.
Allopurinol-induced hypersensitivity reactions tend to occur more often in the presence of renal insufficiency and/or concomitant thiazide diuretic therapy.
Hypersensitivity side effects have included hypersensitivity maculopapular rash (1% to 3%). Rash, eosinophilia, and fever have been reported in 0.3% of patients. Rare, but potentially fatal, reactions have included arthralgias, hepatitis, acute interstitial nephritis, vasculitis, and severe skin reactions. Stevens-Johnson syndrome, toxic epidermal necrolysis, and toxic pustuloderma have been reported rarely. At least 3 cases of allopurinol hypersensitivity syndrome have also been reported.
Hypersensitivity appears to play a role in allopurinol-induced hepatotoxicity. Hepatitis is usually accompanied by fever, rash, and occasionally hepatomegaly. Liver biopsies in cases of hepatitis have revealed mild portal inflammation and acute centrilobular necrosis, consistent with hypersensitivity reactions.
Hepatic side effects have included elevations in serum transaminases and alkaline phosphatase. Cholestatic jaundice, hepatic necrosis, granulomatous hepatitis, and hepatomegaly have been reported rarely.
A first of a kind case report, elevations in pancreatic exocrine enzyme level, new-onset type 1 diabetes mellitus, and allopurinol hypersensitivity syndrome have been reported in a 58-year-old Cambodian female.
Gastrointestinal side effects including diarrhea, nausea, and vomiting have been reported in less than 1% of patients. At least one case of steatorrhea has also been reported, in addition to a case of elevations in pancreatic exocrine enzyme level.
Hematologic side effects including bone marrow suppression, resulting in severe anemia, thrombocytopenia, and leukopenia have been reported in 0.2% of patients. In addition, aplastic anemia, sometimes fatal, and hemolytic anemia have been reported. At least one case of pure red cell aplasia has also been reported.
A 43-year-old female with chronic kidney disease developed fever, generalized morbilliform rash, leukocytosis with marked eosinophilia, and hepatic dysfunction 3 weeks after starting allopurinol therapy (300 mg/day for 3 days followed by 200 mg/day) for hyperuricemia and arthritis. Pure red cell aplasia was suspected due to progressive worsening of anemia with reticulocytopenia. Treatment with recombinant human erythropoietin was initiated in addition to prednisolone 15 mg daily. Eleven days later (approximately 7 weeks after allopurinol was discontinued), both the hemoglobin level and reticulocyte count began to rise.
Renal side effects have included crystalluria and stone formation as well as elevations in blood urea nitrogen. Acute interstitial nephritis due to hypersensitivity and granulomatous nephritis have also been reported.
Studies of patients with allopurinol-induced crystalluria and nephrolithiasis have revealed both urate and allopurinol/oxypurinol (allopurinol metabolite) calculi. Biopsies in cases of suspected allopurinol-associated acute renal failure have revealed vasculitis, interstitial nephritis, and rare cases of granulomatous nephritis.
Nervous system side effects have been reported extremely rarely and included case reports of peripheral neuropathy, catatonia, and cerebral vasculitis associated with allopurinol hypersensitivity. At least two cases of allopurinol-induced aseptic meningitis have also been reported.
Allopurinol-induced aseptic meningitis has been reported in two isolated cases where 60-year-old Caucasian men developed high fevers soon after taking an initial dose of 300 mg allopurinol, and when rechallenged, with quick improvement after allopurinol was stopped.
There is a case report of a patient with no history of psychiatric disease whose allopurinol-associated catatonia, rash, and fever responded to steroids.
Ocular side effects have included cataract formation. Macular retinitis, iritis, conjunctivitis, and amblyopia have also been reported, although causality is unknown.
Anterior lens thinning is associated with cataract formation, and is more common among patients on allopurinol therapy.
Immunologic side effects have included at least one case of ANCA-positive vasculitis.
Antineutrophil cytoplasmic antibodies (ANCA) against human neutrophil elastase as well as against myeloperoxidase were documented in a 47-year-old man who developed vasculitis during allopurinol therapy for gout. Clinical improvement and decline in antibodies were noted upon discontinuation of allopurinol.
A first of a kind case report, new-onset type 1 diabetes mellitus, elevations in pancreatic exocrine enzyme level, and allopurinol hypersensitivity syndrome have been reported in a 58-year-old Cambodian female.
Metabolic side effects including at least one case of new-onset type 1 diabetes mellitus have been reported.
Musculoskeletal side effects have included acute attacks of gout.
More allopurinol resources
- allopurinol MedFacts Consumer Leaflet (Wolters Kluwer)
- allopurinol Concise Consumer Information (Cerner Multum)
- allopurinol Advanced Consumer (Micromedex) - Includes Dosage Information
- Allopurinol Prescribing Information (FDA)
- Allopurinol Professional Patient Advice (Wolters Kluwer)
- Allopurinol Monograph (AHFS DI)
- Aloprim Advanced Consumer (Micromedex) - Includes Dosage Information
- Aloprim Prescribing Information (FDA)
- Zyloprim Prescribing Information (FDA)
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