SIDE EFFECTS: Stomach upset, nausea, diarrhea, or drowsiness may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.Tell your doctor immediately if any of these rare but very serious side effects occur: numbness/tingling of arms/legs, easy bleeding/bruising, signs of infection (e.g., fever, persistent sore throat), unusual tiredness, painful/bloody urination, change in the amount of urine, yellowing eyes/skin, severe stomach/abdominal pain, persistent nausea/vomiting, dark urine, unusual weight loss, eye pain, vision changes.A very serious (possibly fatal) allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.In the US -Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

PRECAUTIONS: Before taking allopurinol, tell your doctor or pharmacist if you are allergic to it; or if you have had a severe reaction to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.Before using this medication, tell your doctor or pharmacist your medical history, especially of: liver disease, kidney disease, diabetes, high blood pressure (hypertension), unusual diets (e.g., fasting).This drug may make you drowsy. Do not drive, use machinery, or do any activity that requires alertness until you are sure you can perform such activities safely.Alcohol may decrease the effectiveness of this drug. Limit alcoholic beverages.Kidney function declines as you grow older. This medication is removed by the kidneys. Therefore, older adults may be at greater risk for side effects while using this drug.During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.Allopurinol passes into breast milk. Consult your doctor before breast-feeding.

Report Problems to the Food and Drug Administration You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088. Need help identifying pills and medications? Use the pill identifier tool on RxList.