How does this medication work? What will it do for me?

Allopurinol is an inhibitor of xanthine oxidase, a substance in the body that is responsible for the product of uric acid. It is used to prevent gout, kidney stones, and kidney damage caused by uric acid. It is also used to reduce the levels of uric acid in the blood that occur because of blood disorders associated with cancer such as leukemias and lymphomas.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

100 mg
Each white, round, biconvex, scored tablet engraved with "ALL" over "100" on one side contains allopurinol 100 mg. Nonmedicinal ingredients: croscarmellose sodium, magnesium stearate, and colloidal silicon dioxide.

200  mg
Each peach, round, biconvex, scored tablet engraved with "ALL" over "200" on one side contains allopurinol 200 mg. Nonmedicinal ingredients: croscarmellose sodium, magnesium stearate, colloidal silicon dioxide, and Sunset Yellow Aluminium Lake.

300 mg
Each orange, round, biconvex, scored tablet engraved with "ALL" over "300" on one side contains allopurinol 300 mg. Nonmedicinal ingredients: croscarmellose sodium, magnesium stearate, colloidal silicon dioxide, and Sunset Yellow Aluminium Lake.

How should I use this medication?

The recommended dose ranges from 100 mg to 800 mg daily in 1 to 3 divided doses taken after food, depending on the condition being treated.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store at room temperature in a dry place and keep out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Allopurinol should not be given to or taken by anyone who:

  • is allergic to, or who has previously developed a severe reaction to, allopurinol or any ingredients of this medication
  • is a child (except for high levels of uric acid caused by cancer)
  • is a nursing mother (except for high levels of uric acid caused by cancer)

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.
  • diarrhea
  • drowsiness
  • headache
  • indigestion
  • nausea or vomiting occurring without other side effects
  • stomach pain occurring without other side effects
  • taste perversion
  • unusual hair loss

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • loosening of fingernails
  • numbness, tingling, pain, or weakness in hands or feet
  • pain in lower back or side
  • unexplained nosebleeds

Stop taking the medication and seek immediate medical attention if any of the following occur:

  • black, tarry stools
  • bleeding sores on lips
  • blood in urine or stools
  • chills, fever, muscle aches or pains, nausea or vomiting (especially if this happens with or shortly after a skin rash)
  • difficult or painful urination
  • hives
  • itching
  • pinpoint-sized red spots on skin
  • red, thickened, or scaly skin
  • red or irritated eyes
  • redness, tenderness, burning, or peeling of skin
  • shortness of breath, trouble breathing, tightness in chest, or wheezing
  • skin rash or sores
  • sore throat and fever
  • sores, ulcers, or white spots in mouth or on lips
  • sudden decrease in amount of urine
  • swelling in stomach area
  • swelling of face, fingers, feet, or lower legs
  • swollen or painful glands
  • unusual bleeding or bruising
  • unusual tiredness or weakness
  • weight gain (rapid)
  • yellow eyes or skin

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin taking a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should take this medication.

Drowsiness/reduced alertness: This medication may make you drowsy. Use appropriate caution if you plan to do activities requiring alertness.

Gout: Do not start allopurinol treatment until an acute attack of gout has completely subsided, as further attacks may be brought on by this medication. Acute gout attacks may be brought on at the start of treatment with allopurinol for people who have not taken the medication before. If an acute gout attack develops after starting this medication, call your doctor.

Skin rash: If you develop a skin rash, stop taking this medication and contact your doctor. The skin rash may be the first sign of a serious allergic reaction to the medication.

Pregnancy: Allopurinol is not recommended for use by women who are or may become pregnant unless, in the judgment of their doctor, the potential benefits outweigh the possible risks. If you are or may be pregnant, talk to your doctor about the risks and benefits of this medication.

Breast-feeding: Allopurinol is believed to pass into breast milk. Nursing women should not use this medication.

Children: Children should not take allopurinol, except in cases where increased uric acid levels in the blood are associated with cancer or with Lesch-Nyhan syndrome. The safety and effectiveness of allopurinol for this age group have not been established in treatment of other conditions.

What other drugs could interact with this medication?

There may be an interaction between allopurinol and any of the following:

  • aluminum salts (e.g., antacids containing aluminum)
  • ampicillin
  • amoxicillin
  • azathioprine
  • bleomycin
  • chlorpropamide
  • cyclophosphamide
  • cyclosporine
  • doxorubicin
  • mechlorethamine
  • mercaptopurine
  • phenytoin
  • probenecid
  • procarbazine
  • salicylates (e.g., ASA)
  • theophyllines (e.g., aminophylline, oxtriphylline, theophylline)
  • vidarabine
  • warfarin

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.

All material copyright MediResource Inc. 1996 – 2018. Terms and conditions of use. The contents herein are for informational purposes only. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Source: