Allopurinol for the Treatment of Gout

Uses, Side Effects, Interactions

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Allopurinol treats gout, hyperuricemia (the buildup of uric acid in the body), and kidney stones. It is part of a class of drugs called xanthine oxidase inhibitors and is available in the United States under the brand names Zyloprim and Lopurin.

Allopurinol works by reducing the production of uric acid in the body. It is also prescribed to prevent gout attacks. Gout is a type of inflammatory arthritis that causes severe swelling and pain in one joint at a time, usually the big toe.  

This article covers how allopurinol treats gout, its side effects, and possible drug interactions.

Gout in big toe

Toa55 / Getty Images

Using Allopurinol for Gout  

Allopurinol is a long-term, preventive treatment for gout. It is regularly prescribed to stop gout attacks and prevent joint damage.  

Gout commonly occurs because of high uric acid levels in the blood. Typically, the body rids itself of uric acid through urine. But if too much uric acid is produced, the body cannot get rid of it properly, and urate crystals will start forming around the joints.

This uric acid buildup can occur over many years without a person ever knowing it. Once crystals have formed, they make their way into the synovial lining (joint lining), causing inflammation and pain.                                                              ,

Allopurinol works by reducing the amount of uric acid in the blood. Once uric acid is low or normal, crystals stop forming, and existing crystals will slowly dissolve. Urate crystals might take many years to dissolve, but gout attacks and joint damage no longer occur once levels are low enough.

For uric acid levels to remain normal, you must keep taking allopurinol. But because it takes many months or even years for this to happen, you might still have gout attacks. The longer you have had high uric acid levels, the longer it will be before you stop experiencing gout attacks and for your uric acid levels to become normal.

A healthcare provider will likely prescribe allopurinol as soon as you are diagnosed with gout to prevent future gout attacks and joint damage. They might also prescribe allopurinol if your blood work shows high uric acid levels (even if you have not yet experienced gout attacks) or if your skin shows firm, white lumps called tophi.

Allopurinol is an oral pill and is taken once or twice daily. You should take it with a meal and at the same time every day. Take allopurinol exactly as prescribed. Do not miss doses or take more or less than prescribed.

Allopurinol Side Effects  

Side effects are unwanted results from taking a medication. Most drug side effects are mild, but a few can be serious. The research on allopurinol shows it to be well-tolerated by most people, and any adverse or severe reactions are rare.

You likely will not experience any severe side effects with allopurinol, and mild side effects will resolve once your body gets used to the drug.

Common side effects of allopurinol include: 

  • Rash
  • Headache
  • Upset stomach
  • Diarrhea
  • Dizziness
  • Feeling drowsy
  • Feeling sick
  • Changes to your sense of taste

You should immediately reach out to your healthcare provider if you develop a rash or flu-like symptoms while on allopurinol. You should also speak to your healthcare provider if you develop symptoms or side effects that cause you concern. 

Allopurinol can sometimes trigger a gout attack at the start of treatment. This reaction might occur because the crystals find their way into the synovial linings of joints due to their smaller size.  

Your healthcare provider might prescribe another medication, such as Colcrys (colchicine), an anti-inflammatory drug that reduces gout swelling and pain. Colchicine is recommended in the first few months of using allopurinol.

Allopurinol Interactions

A drug interaction might change how a medication works or increase the risk for serious side effects. According to the Food and Drug Administration (FDA), if you experience a drug interaction, it would fall under three categories.

These categories are: 

  • Drug-to-drug interactions in which two or more drugs react with each other
  • Drug to food or beverage interactions in which drugs respond to being used with certain foods or beverages
  • Drug condition reactions where a drug reacts to an existing health condition and causes harm 

Some medications can interact with allopurinol and increase the potential for side effects. According to the FDA's package insert for Zyloprim (allopurinol), medicines that might interact with allopurinol include:

There are no specific foods or drinks that you need to avoid with allopurinol. However, consider your alcohol intake because alcohol is a gout attack trigger.

Some people shouldn't take allopurinol. This includes people with kidney problems or a history of kidney disease, pregnant people, those who are breastfeeding, and children and youth under age 18.  

To avoid drug interactions, keep a list of all the medicines, vitamins, and supplements you use and share it with your healthcare provider or pharmacist. Do not start, stop, or change the dose of any medication without first talking with your healthcare provider. 

Summary  

Allopurinol is a drug that reduces uric acid production in the body. Your healthcare provider might prescribe allopurinol to prevent future gout attacks and joint damage. It is given as an oral pill and taken once or twice a day.  

For your uric acid levels to remain normal, you must take allopurinol daily and as prescribed by your healthcare provider. The medication might take some time to start working, so your healthcare provider will prescribe a medication like colchicine in the first few months of treatment.  

The research on allopurinol shows it to be well-tolerated, and adverse and severe reactions are rare. Even so, you should let your healthcare provider or pharmacist know about all the medications you take, including vitamins and supplements. Never make changes to your treatment plan without first talking to your healthcare provider.  

A Word From Verywell

Gout is a treatable and manageable condition. Medications like allopurinol can improve your outlook and quality of life.

Work with a healthcare provider to find additional ways to lower your uric acid levels, improve joint function, and prevent tophi. They can recommend lifestyle and diet changes to help ease your symptoms and reduce the frequency and severity of gout attacks.

Frequently Asked Questions

  • How long does it take for allopurinol to lower uric acid levels?

    It might take a month or two to experience the effects of allopurinol, and it is possible to have gout attacks during this time. Your healthcare provider can prescribe an anti-inflammatory treatment like colchicine to prevent these attacks. Do not stop taking allopurinol without talking to your healthcare provider.

  • What are the common side effects of allopurinol?

    Common side effects of allopurinol include rash, headache, upset stomach, dizziness, and drowsiness. You should immediately reach out to a healthcare provider if you develop a rash, flu-like symptoms, or any side effects that cause you concern.

  • Does allopurinol cause weight gain?

    Weight loss is more common with allopurinol than weight gain. You should reach out to a healthcare provider if you experience any unexplained weight loss or weight gain.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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