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Allopurinol (By mouth)

Allopurinol (al-oh-PURE-i-nol)

Treats gout and kidney stones. Also lowers the amount of uric acid in the blood.

Brand Name(s):


There may be other brand names for this medicine.

When This Medicine Should Not Be Used:

This medicine is not right for everyone. Do not use it if you had an allergic reaction to allopurinol.

How to Use This Medicine:

Capsule, Tablet

  • Your doctor will tell you how much medicine to use. Do not use more than directed.
  • You may take allopurinol after meals to prevent stomach upset.
  • You may have more gout attacks when you start using this medicine. Keep using the medicine even if this happens. Your doctor may give you other medicines (including colchicine, NSAIDs) to prevent gout attacks. The attacks should become shorter and less severe after you take allopurinol for several months.
  • Drink extra fluids so you will urinate more often and help prevent kidney problems. Drink about 10 to 12 full glasses of water each day, unless otherwise directed by your doctor.
  • You should also increase your fiber intake.
  • Missed dose: Take a dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed dose.
  • Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.

Drugs and Foods to Avoid:

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

  • Some foods and medicines can affect how allopurinol works. Tell your doctor if you are using any of the following:
    • Amoxicillin, ampicillin, azathioprine, chlorpropamide, cyclosporine, dicumarol, mercaptopurine, sulfinpyrazone
    • Blood thinner (including dicumarol, warfarin)
    • Diuretic (water pill)
  • Do not take large doses of vitamin C while you are using allopurinol.
  • You may need to lessen your intake of animal protein, sodium, refined sugars, or foods rich in oxalate and calcium, especially if you have kidney stones that keep coming back.

Warnings While Using This Medicine:

  • Tell your doctor if you are pregnant or breastfeeding, or if you have kidney disease, liver disease, diabetes, high blood pressure, heart failure, seizures, or cancer (including multiple myeloma).
  • This medicine may cause the following:
    • Liver problems
    • Kidney problems
  • This medicine may cause serious skin reactions. Check with your doctor right away at the first sign of a skin rash or allergic reaction.
  • This medicine may make you drowsy. Do not drive or do anything else that could be dangerous until you know how this medicine affects you.
  • Your doctor will do lab tests at regular visits to check on the effects of this medicine. Keep all appointments.
  • Keep all medicine out of the reach of children. Never share your medicine with anyone.

Possible Side Effects While Using This Medicine:

Call your doctor right away if you notice any of these side effects:

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Blistering, peeling, red skin rash
  • Dark urine or pale stools, loss of appetite, stomach pain, nausea, vomiting, yellow skin or eyes
  • Pain when you urinate, cloudy or bloody urine, change in how much or how often you urinate

If you notice these less serious side effects, talk with your doctor:

  • Diarrhea
  • Drowsiness

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Last Updated: 5/1/2020

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