Allopurinol for Gout: Side Effects and Indications

You must note that allopurinol doesn't cure a gout attack, people mainly use it as a prevention method when a person is undergoing treatment with other drugs.
Allopurinol for Gout: Side Effects and Indications
María Vijande

Reviewed and approved by the pharmacist María Vijande.

Written by María Vijande

Last update: 27 May, 2022

Allopurinol is a medication for the treatment of gout and for controlling high levels of uric acid in the body. It’s prescribed in cases where the gout is due to side effects caused by other drugs. For instance, those used for the treatment of cancer and kidney stones.

It owes its action to its ability to reduce the synthesis of uric acid, which is responsible for triggering the clinical symptoms of gout. This way, Allopurinol belongs to the family of drugs known as xanthine oxidase inhibitors. This is an enzyme necessary for the synthesis of uric acid. In this article, you’ll learn more about this process in more detail.

However, you must keep in mind that Allopurinol doesn’t exactly cure gout attacks. Instead, it’s merely a method of prevention for patients undergoing treatment with other drugs, such as those we mentioned above.

What’s gout?

A person looking at their feet.
Patients with gout, a well-known disease, usually experience acute inflammation, especially in their big toe.

Gout usually manifests as acute joint-type inflammation, usually in the big toe. In other words, gout causes an asymptomatic inflammation in a joint as it swells and causes pain for a short amount of time.

This inflammation happens due to the presence of monosodium urate crystals. This substance is an excess of uric acid in the blood. Elevated levels of this acid usually have to do with bad lifestyle habits, such as poor diet and alcohol intake. When these levels normalize in a sustained manner, the crystals usually dissolve without a problem.

Hyperuricemia is the condition of a person who has high uric acid levels. However, although this condition is common (it afflicts 7% of men), only a minority of people develop the characteristic gout crystals.

When a gout attack is over, some monosodium urate crystals remain in their joints. So, even if the treatment is over, the person could have another gout attack at any time.

Allopurinol – side effects

Side effects are more common in patients with renal or hepatic impairment. And the reason for this is that Allopurinol metabolizes in the liver and is excreted by the kidneys. Thus, due to these changes, drug concentrations in the body could either increase or decrease.

Their effect increases together with those concentrations. So, it’s easier for a patient to experience side effects. Let’s look at the most common unwanted effects this medication produces.

Skin reactions due to Allopurinol

A person scratching their arm.
One of the adverse effects of allopurinol is pruritus. But other skin reactions may also occur.

These are the most common and may appear at any time during treatment with Allopurinol. Among them:

  • Pruritus
  • Skin peeling
  • Purpuric lesions
  • Exfoliation
  • Skin rashes

If the first four of these occur, you should discontinue treatment with this medication. You could restart and gradually increase the dose after recovering. But if you get a rash then you must discontinue it permanently.

Generalized hypersensitivity reactions

Even though it doesn’t happen frequently, there might be some hypersensitivity reactions such as:

  • Fever
  • Stevens-Johnson or Lyell syndromes
  • Lymphadenopathy
  • Vasculitis (this can manifest in various ways including hepatitis, nephritis, and epilepsy)

If these reactions occur, you must stop treatment with Allopurinol immediately and forever. In these cases, your doctor will most likely prescribe corticosteroids in order to reverse these generalized hypersensitivity symptoms.

Gastrointestinal disorders

A person vomiting after taking Allopurinol.
Nausea and vomiting are the most frequent digestive manifestations after ingesting this medication.

The most common reactions in the digestive system are nausea and vomiting. To avoid this, you must never take Allopurinol after a meal.

Granulomatous hepatitis due to Allopurinol

This adverse reaction seldom happens without the obvious evidence of a more generalized hypersensitivity. Once you interrupt treatment its side effects seem to reverse.


Allopurinol is a very effective drug for preventing gout attacks caused by the intake of other drugs. This is because it’s a medication subject to medical prescription. So, you shouldn’t self-medicate. Mainly because the misuse of this medicine can lead to serious health problems.

Consult your doctor or pharmacist for any questions you may have or for information about any side effects.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

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  • Domínguez J, Trindade C, Alonso A, Castellano A et al. Hipersensibilidad al alopurinol: Eficacia de un protocolo de desensibilización en tres casos. An. Med. Interna (Madrid). 2001;18(1):27-28.
  • Rødevand E, Sletvold O, Kvande KT. Side effects off allopurinol. Tidsskr Nor Laegeforen. 2004 Oct 21;124(20):2618-9.
  • Childs L, Dow C. Allopurinol-induced hepatomegaly. BMJ Case Rep. 2012 Oct 19;2012:bcr2012007283.
  • Iqbal U, Siddiqui HU, Anwar H, Chaudhary A et al. Allopurinol-Induced Granulomatous Hepatitis: A Case Report and Review of Literature. J Investig Med High Impact Case Rep. 2017 Sep 8;5(3):2324709617728302.
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This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.