Allopurinol for Kidney Stones

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Allopurinol for Kidney Stones


Generic NameBrand Name
allopurinolLopurin, Zyloprim

How It Works

Allopurinol makes it more difficult for your body to make uric acid. This decreases the amount of uric acid in the urine, reducing the chance that a uric acid kidney stone will form.

Why It Is Used

Allopurinol may be used if you have:

  • Uric acid kidney stones or high levels of uric acid in the urine.
  • Kidney stones for which no specific cause can be found.

How Well It Works

Allopurinol prevents uric acid stones from forming. It can also dissolve existing small uric acid stones.

Side Effects

All medicines have side effects. But many people don't feel the side effects, or they are able to deal with them. Ask your pharmacist about the side effects of each medicine you take. Side effects are also listed in the information that comes with your medicine.

Here are some important things to think about:

  • Usually the benefits of the medicine are more important than any minor side effects.
  • Side effects may go away after you take the medicine for a while.
  • If side effects still bother you and you wonder if you should keep taking the medicine, call your doctor. He or she may be able to lower your dose or change your medicine. Do not suddenly quit taking your medicine unless your doctor tells you to.

Call 911 or other emergency services right away if you have:

  • Trouble breathing.
  • Swelling of your face, lips, tongue, or throat.
  • Skin rash.

Call your doctor if you have:

  • Hives.

Common side effects of this medicine include:

  • Rash. This is a common side effect, but it can be a sign of a very serious or life-threatening condition.
  • Diarrhea and nausea.
  • Increased gout attacks at first. To avoid this, your doctor may also prescribe either colchicine, which blocks the inflammation caused by uric acid crystals, or low-dose nonsteroidal anti-inflammatory drugs (NSAIDs). After normal uric acid levels have been maintained for 6 to 12 months and no further attacks occur, colchicine or NSAIDs do not need to be taken.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

You may be able to reduce the amount of uric acid in your urine by decreasing the amount of red meat protein in your diet.

Allopurinol can interfere with many other medicines. It may increase or decrease the levels of other medicines, which may raise the toxicity of these medicines or reduce their effectiveness. Be sure your doctor knows about all prescription and over-the-counter medicines and dietary supplements you are taking.

Taking medicine

Medicine is one of the many tools your doctor has to treat a health problem. Taking medicine as your doctor suggests will improve your health and may prevent future problems. If you don't take your medicines properly, you may be putting your health (and perhaps your life) at risk.

There are many reasons why people have trouble taking their medicine. But in most cases, there is something you can do. For suggestions on how to work around common problems, see the topic Taking Medicines as Prescribed.

Advice for women

If you are pregnant, breast-feeding, or trying to get pregnant, do not use any medicines unless your doctor tells you to. Some medicines can harm your baby. This includes prescription and over-the-counter medicines, vitamins, herbs, and supplements. And make sure that all your doctors know that you are pregnant, breast-feeding, or planning to get pregnant.


Liver and kidney function studies may be done after a few months of using allopurinol. The studies may be repeated now and then.

Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.

Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.


ByHealthwise Staff
Primary Medical ReviewerAnne C. Poinier, MD - Internal Medicine
Specialist Medical ReviewerTushar J. Vachharajani, MD, FASN, FACP - Nephrology
Last RevisedMay 14, 2012

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