What is allopurinol?


Generic Name: Allopurinol Brand Name(s): Generics only. No brands available.

Know the basics

What is allopurinol used for?

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.

How should I take allopurinol?

Take this medication by mouth, usually once daily or as directed by your doctor. Take this medication after a meal to reduce stomach upset. If your dose is more than 300 milligrams a day, you will need to take several smaller doses during the day to get this amount (ask your doctor for directions).

It is best to drink a full glass of water with each dose and at least 8 more glasses (8 ounces each) of fluid a day. If your doctor has directed you to drink less fluid for other medical reasons, consult your doctor for further instructions. Your doctor may also instruct you on how to decrease acid in your urine (e.g., avoiding large amounts ofascorbic acid/vitamin C).

Dosage is based on your medical condition and response to treatment. Use this medication regularly to get the most benefit from it. To help you remember, take it at the same time(s) each day.

For the treatment of gout, it may take up to several weeks for this medicine to have an effect. You may have more gout attacks for several months after starting this medicine while the body removes extra uric acid. Allopurinol is not a pain reliever. To relieve pain from gout, continue to take your prescribed medicines for gout attacks (e.g., colchicine, ibuprofen, indomethacin) as directed by your doctor.

Tell your doctor if your condition persists or worsens.

How do I store allopurinol?

Allopurinol is best stored at room temperature away from direct light and moisture. To prevent drug damage, you should not store allopurinol in the bathroom or the freezer. There may be different brands of allopurinol that may have different storage needs. It is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.

You should not flush allopurinol down the toilet or pour them into a drain unless instructed to do so. It is important to properly discard this product when it is expired or no longer needed. Consult your pharmacist for more details about how to safely discard your product.

Know the precautions & warnings

What should I know before using allopurinol?

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.

Is it safe to take allopurinol during pregnancy or breast-feeding?

There are no adequate studies in women for determining risk when using this medication during pregnancy or while breastfeeding. Please always consult with your doctor to weigh the potential benefits and risks before taking this medication. This medication is pregnancy risk category C according to the US Food and Drug Administration (FDA).

FDA pregnancy risk category reference below:

  • A=No risk,
  • B=No risk in some studies,
  • C=There may be some risk,
  • D=Positive evidence of risk,
  • X=Contraindicated,
  • N=Unknown.

Know the side effects

What are the side effects of allopurinol?

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Stop using allopurinol and call your doctor at once if you have a serious side effect such as:

  • Fever, sore throat, and headache with a severe blistering, peeling, and red skin rash;
  • The first sign of any skin rash, no matter how mild;
  • Pain or bleeding when you urinate;
  • Nausea, upper stomach pain, itching, loss of appetite, weight loss, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes);
  • Urinating less than usual or not at all;
  • Joint pain, flu symptoms;
  • Severe tingling, numbness, pain, muscle weakness; or
  • Easy bruising, unusual bleeding (nose, mouth, vagina, or rectum), purple or red pinpoint spots under your skin.

Less serious side effects may include:

  • Vomiting, diarrhea;
  • Drowsiness, headache;
  • Changes in your sense of taste;
  • Muscle pain.

Not everyone experiences these side effects. There may be some side effects not listed above. If you have any concerns about a side-effect, please consult your doctor or pharmacist.

Know the interactions

What drugs may interact with allopurinol?

Allopurinol may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects. To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, non-prescription drugs and herbal products) and share it with your doctor and pharmacist. For your safety, do not start, stop, or change the dosage of any drugs without your doctor’s approval.

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor’s approval.

  • Azathioprine (Imuran);
  • Chlorpropamide (Diabinese);
  • Cyclosporine (Gengraf, Sandimmune, Neoral);
  • Mercaptopurine (Purinethol);
  • An antibiotic such as ampicillin (Principen, Omnipen, others) or amoxicillin (Amoxil, Augmentin, Trimox, Wymox);
  • A blood thinner such as dicoumarol or warfarin (Coumadin);
  • A diuretic (water pill).

Does food or alcohol interact with allopurinol?

Allopurinol may interact with food or alcohol by altering the way the drug works or increase the risk for serious side effects. Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.

What health conditions may interact with allopurinol?

Allopurinol may interact with your health condition. This interaction may worsen your health condition or alter the way the drug works. It is important to always let your doctor and pharmacist know all the health conditions you currently have, especially:

  • Bone marrow problems;
  • Liver disease—Use with caution. May make these conditions worse.
  • Kidney disease—Use with caution. The effects may be increased because of slower removal of the medicine from the body.

Understand the dosage

The information provided is not a substitute for medical advice. Always consult your doctor or pharmacist before using this medication.

What is the dose of allopurinol for an adult?

Usual Adult Dose for Gout:

  • Initial: 100 mg orally once a day.
  • Maintenance: 200 to 300 mg (mild gout) orally once a day or 400 to 600 mg/day (moderately severe tophaceous gout) in divided doses.

Usual Adult Dose for Hyperuricemia Secondary to Chemotherapy:

  • Parenteral: 200 to 400 mg/m2/day to a maximum of 600 mg/day
  • Oral: 600 to 800 mg/day for 1 to 3 days with consumption of at least 2 liters of fluid/day.
  • Maintenance: 200 to 300 mg/day orally until patient no longer at high risk for developing hyperuricemia.

Usual Adult Dose for Calcium Oxalate Calculi with Hyperuricosuria:

  • Initial: 200 to 300 mg orally once a day.
  • Maintenance: 300 mg/day or less.

Usual Adult Dose for Congestive Heart Failure:

  • Study (n=11) to prevent the formation of superoxide free radicals and improve endothelial function (in NYHA class II to III chronic heart failure): 300 mg orally daily for 1 month

Usual Adult Dose for Cardiothoracic Surgery:

  • Studies: Coronary Artery Bypass Graft Surgery
    600 mg orally one day prior to surgery and another 600 mg orally the day of surgery.

Usual Adult Dose for Leishmaniasis:

  • Study (n=31 – Cutaneous leishmaniasis: 20 mg/kg/day plus low-dose meglumine antimoniate (30 mg/kg/day) for 20 days.

Usual Adult Dose for Mania:

  • Case Reports – Mania (bipolar I) associated with hyperuricemia: 300 mg orally daily.

Usual Adult Dose for High Risk Percutaneous Transluminal Angioplasty

  • Study (n=38) – Primary Percutaneous Transluminal Coronary Angioplasty (PTCA):
    400 mg orally administered immediately after admission to the emergency department (approximately 60 minutes before reperfusion) and after primary PTCA was completed.

Usual Adult Dose for Reactive Perforating Collangenosis:

  • Case Report: 100 mg orally daily.

What is the dose of allopurinol for a child?

Usual Pediatric Dose for Hyperuricemia Secondary to Chemotherapy

  • Parenteral :
    Less than or equal to 10 years: 200 mg/m2/day in 1 to 3 equally divided doses not to exceed 600 mg/24 hours. All doses greater than 300 mg should be given in equally divided doses.
    Greater than 10 years: 200 to 400 mg/m2/day administered in 1 to 3 equally divided doses, not to exceed 600 mg/24 hours.
  • Oral:
    Less than 6 years: 150 mg/day orally in 3 divided doses.
    6 to 10 years: 300 mg/day orally in 2 to 3 divided doses.
    Greater than 10 years: 600 to 800 mg/day in 2 to 3 equally divided doses

Usual Pediatric Dose for Leishmaniasis

  • Greater than 5 years old
  • Study (n=31) – Cutaneous leishmaniasis: 20 mg/kg/day plus low-dose meglumine antimoniate (30 mg/kg/day) for 20 days.

How is allopurinol available?

Allopurinol is available in the following dosage forms and strengths:

Tablet, Oral: 100 mg, 300 mg.

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services or go to your nearest emergency room.

What should I do if I miss a dose?

If you miss a dose of allopurinol, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.

Hello Health Group does not provide medical advice, diagnosis or treatment.

Review Date: May 30, 2016 | Last Modified: July 26, 2017

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