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Drug Profile

The information on this site is intended to supplement and enhance, not replace, the advice of a physician who is familiar with your medical history. Decisions about your health should always be made ONLY after detailed conversation with your doctor.

Limited Use [what does this mean?]
Generic drug name: allopurinol (al oh PURE i nole)
Brand name(s): LOPURIN, ZYLOPRIM
GENERIC: available FAMILY: Drugs for Arthritis and Gout
Find the drug label by searching at DailyMed.

Pregnancy and Breast-feeding Warnings [top]

Pregnancy Warning

There is a published report of allopurinol causing deaths and malformations in an animal study. Because of the potential for serious adverse effects to the fetus, this drug should not be used by pregnant women.

Breast-feeding Warning

Allopurinol is excreted in human milk. Because of the potential for adverse effects in nursing infants, you should not take this drug while nursing.

Facts About This Drug [top]

Allopurinol helps to prevent gout attacks. Gout occurs when there is a high level of uric acid in the body, and a gout attack occurs when crystals of uric acid form in the joints and the body releases chemicals in response to the crystals. This causes pain and inflammation. Allopurinol works by decreasing production of uric acid, thereby lowering the level of uric acid in the blood.[1]

Allopurinol will not relieve a gout attack that has already started. If you are taking allopurinol, keep...

Allopurinol helps to prevent gout attacks. Gout occurs when there is a high level of uric acid in the body, and a gout attack occurs when crystals of uric acid form in the joints and the body releases chemicals in response to the crystals. This causes pain and inflammation. Allopurinol works by decreasing production of uric acid, thereby lowering the level of uric acid in the blood.[1]

Allopurinol will not relieve a gout attack that has already started. If you are taking allopurinol, keep taking it during an attack, even if another drug is prescribed to treat the attack.

After you start using allopurinol, your gout attacks may become more frequent for a while. Keep taking the drug. If you take it regularly, the attacks gradually will become less frequent and less painful, and they may stop completely after several months.

Allopurinol can cause skin rashes, allergic reactions, and kidney stones. In some cases, the skin rash and allergic reactions can be life-threatening. Stop taking allopurinol and call your doctor at the first sign of skin rash or allergic reaction.[2] To help prevent kidney stones while taking allopurinol, drink at least 10 to 12 full glasses (eight ounces each) of fluid each day unless your doctor tells you otherwise. Too much vitamin C also increases your risk of forming kidney stones, so do not take vitamin C supplements while you are taking allopurinol unless you have checked with your doctor first.

Allopurinol should not be used to lower high levels of uric acid in the body in patients without gout symptoms. In such patients the increased risk of life-threatening skin reactions outweighs any benefit of the drug.[3]

Results of two clinical trials published in the New England Journal of Medicine in 2020 showing that treatment with allopurinol did not slow the decline in kidney function in patients with chronic kidney disease.[4],[5]

Before You Use This Drug [top]

Tell your doctor if you have or have had:

  • history of allergy to allopurinol
  • kidney function impairment
  • diabetes
  • heart disease or high blood pressure
  • pregnancy or are breast-feeding

Tell your doctor about any other drugs you take, including aspirin, herbs, vitamins, and other nonprescription products.

When You Use This Drug [top]

  • Do not drink alcohol. Alcohol increases the amount of uric acid in your blood and may make your gout attacks more frequent and more difficult to control. It also increases your risk of stomach problems.
  • Discontinue immediately if a skin rash develops.
  • Drink large amounts of fluids.
  • Until you know how you react to this drug, do not drive or perform other activities requiring alertness. Allopurinol can cause drowsiness.

How to Use This Drug [top]

  • If you miss a dose, take it as soon as you remember, but skip it if it is almost time for the next dose. Do not take double doses.
  • Do not share your medication with others.
  • Take the drug at the same time(s) each day.
  • Take after meals to decrease stomach upset. If this does not work and your stomach continues to be upset, check with your doctor.
  • Store at room temperature with lid on tightly. Do not store in the bathroom. Do not expose to heat, moisture, or strong light. Keep out of reach of children.

Interactions with Other Drugs [top]

The following drugs, biologics (e.g., vaccines, therapeutic antibodies), or foods are listed in Evaluations of Drug Interactions 2003 as causing “highly clinically significant” or “clinically significant” interactions when used together with any of the drugs in this section. In some sections with multiple drugs, the interaction may have been reported for one but not all drugs in this section, but we include the interaction because the drugs in this section are similar to one another. We have also included potentially serious interactions listed in the drug’s FDA-approved professional package insert or in published medical journal articles. There may be other drugs, especially those in the families of drugs listed below, that also will react with this drug to cause severe adverse effects. Make sure to tell your doctor and pharmacist the drugs you are taking and tell them if you are taking any of these interacting drugs:

AMOXIL, ampicillin, amoxicillin, ARA-A, ARABINOSIDE, azathioprine, chlorpropamide, cyclophosphamide, cyclosporine, CYTOXAN, DIABINESE, dicumarol, DILANTIN, ELIXOPHYLLIN, IMURAN, mercaptopurine, OMNIPEN, phenytoin, PURINETHOL, SANDIMMUNE, SLO-BID, THEO-24, theophylline, vidarabine, VIRA-A.

Adverse Effects [top]

Call your doctor immediately if you experience:

  • skin rash, hives, or itching
  • bloody or cloudy urine
  • difficult or painful urination
  • lower back or side pain
  • chills, fever, or muscle aches
  • nausea or vomiting along with chills or fever
  • numbness or tingling of hands or feet
  • red, thick, tender, burning, or peeling skin
  • chill, sore throat, and fever
  • unusual bleeding or bruising
  • unusual tiredness or weakness
  • sudden decrease in amount of urine
  • yellow eyes or skin
  • loosening of fingernails
  • rapid weight gain
  • difficulty breathing
  • tightness in chest or wheezing
  • unexplained nosebleeds
  • bloody or black, tarry stools
  • bleeding sores on lips
  • pinpoint red spots on skin
  • sores, ulcers, or white spots in mouth or on lips
  • swelling in stomach area
  • nausea or vomiting
  • swelling of face, fingers, feet, or lower legs
  • swollen glands

Call your doctor if these symptoms continue:

  • diarrhea
  • drowsiness
  • nausea or vomiting without symptoms of skin rash
  • stomach pain
  • headache
  • chills or fever
  • muscle aches or pains
  • unusual hair loss

Periodic Tests[top]

Ask your doctor which of these tests should be done periodically while you are taking this drug:

  • complete blood count
  • liver function tests
  • kidney function tests
  • blood levels of uric acid

last reviewed February 28, 2021