What special precautions should I follow?  

Before taking allopurinol,

• tell your doctor and pharmacist if you are allergic to allopurinol or any other medications.
• tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking. Be sure to mention any of the following: amoxicillin (Amoxil, Trimox); ampicillin (Polycillin, Principen); anticoagulants ('blood thinners') such as warfarin (Coumadin); cancer chemotherapy drugs such as cyclophosphamide (Cytoxan) and mercaptopurine (Purinethol); chlorpropamide (Diabinese); diuretics ('water pills'); medications that suppress the immune system such as azathioprine (Imuran) and cyclosporine (Neoral, Sandimmune); other medications for gout such as probenecid (Benemid) and sulfinpyrazone (Anturane); and tolbutamide (Orinase). Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
• tell your doctor if you have or have ever had kidney or liver disease or heart failure.
• tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking allopurinol, call your doctor.
• you should know that allopurinol may make you drowsy. Do not drive a car or operate machinery until you know how this medication affects you.
• ask your doctor about the safe use of alcoholic beverages while you are taking allopurinol. Alcohol may decrease the effectiveness of allopurinol.

What special dietary instructions should I follow?  

Drink at least eight glasses of water or other fluids each day while taking allopurinol unless directed to do otherwise by your doctor.

What should I do if I forget a dose?  

Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.