Allopurinol is used to treat gout and certain types of kidney stones. It is also used to prevent increased uric acid levels in patients receiving cancer chemotherapy. These patients can have increased uric acid levels due to release of uric acid from the dying cancer cells. Allopurinol works by reducing the amount of uric acid made by the body. Increased uric acid levels can cause gout and kidney problems.
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 right away if any of these rare but very serious side effects occur: numbness/tingling of arms/legs, easy bleeding/bruising, unusual tiredness, signs of kidney problems (such as change in the amount of urine, painful/bloody urination), yellowing eyes/skin, severe stomach/abdominal pain, persistent nausea/vomiting, dark urine, unusual weight loss, eye pain, vision changes.
This medication can commonly cause a rash that is usually not serious. However, you may not be able to tell it apart from a rare rash that could be a sign of a severe reaction. Get medical help right away if you develop any rash.
A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: fever, swollen lymph nodes, 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.
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. Alcohol or marijuana (cannabis) can make you more drowsy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Alcohol may also decrease the effectiveness of this drug. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).
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.