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Allopurinol (Zyloprim): Uses, Warnings and More

Quick summary: Allopurinol is a medicine used to lower uric acid levels. It is commonly associated with gout and other conditions where uric acid builds up. This article explains its main uses, how it...

Educational content Use this article as a starting point for understanding the topic.
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Safety first Side effects, interactions and risks depend on each person.
Medical disclaimer

This content is for educational purposes only and does not replace medical advice, diagnosis or treatment from a qualified healthcare professional.

Quick summary: Allopurinol is a medicine used to lower uric acid levels. It is commonly associated with gout and other conditions where uric acid builds up. This article explains its main uses, how it works, and the key safety points to review with a healthcare professional.

Medical disclaimer: This content is for general information only and does not replace advice from a doctor, pharmacist, or the official product leaflet. Do not use this page to diagnose a condition or to change any prescribed treatment.

What is allopurinol?

Allopurinol is a medicine used to help lower uric acid in the body. The current content identifies it as being used for acute uric acid and gout, and it notes that the product ingredient is allopurinol sodium.

Brand names listed in the United States include Zyloprim, Lopurin, and Aloprim.

How allopurinol works

Allopurinol lowers uric acid in the blood and urine by inhibiting xanthine oxidase, an enzyme involved in the conversion of hypoxanthine to xanthine and xanthine to uric acid.

In simple terms, it helps reduce uric acid production.

What allopurinol is used for

The original content lists several uses related to urate or uric acid overproduction and deposition. These include:

  • Clinical manifestations of uric acid or urate deposition in idiopathic gout
  • Uric acid lithiasis
  • Acute uric acid nephropathy
  • High urate levels linked to neoplastic and myeloproliferative disease, including after cytotoxic treatment
  • Enzyme-related disorders with urate overproduction, including Lesch-Nyhan syndrome and some glycogen storage disorders
  • 2,8-dihydroxyadenine kidney stones related to deficient adenine phosphoribosyltransferase activity
  • Recurrent mixed renal lithiasis of calcium oxalate when hyperuricosuria is present and other measures have not worked

Dosage information in the source content

The original text includes dose ranges for adults, children, and people with kidney or liver impairment. Because dosing must be individualized, this article does not repeat those numbers as treatment advice.

If you need to verify a dose, check the official leaflet or ask a doctor or pharmacist, especially if there is kidney disease, liver disease, dialysis, or treatment for cancer-related uric acid problems.

Topic What the source says
Main action Reduces uric acid production by inhibiting xanthine oxidase
Common use Gout and uric acid-related conditions
Important caution Hypersensitivity reactions, including rash, are a key warning
Special situations Kidney failure, liver failure, pregnancy, and breastfeeding need careful review

Warnings and precautions

The source content highlights several important precautions:

  • Hypersensitivity to allopurinol is a contraindication.
  • Allopurinol should not be started during an acute gout attack; the source says prophylactic therapy may be started after the attack has fully decreased, with anti-inflammatory treatment also taken.
  • Early treatment may precipitate an acute gouty arthritis attack.
  • Hydration is advised.
  • Rash and other hypersensitivity reactions may require stopping treatment.
  • Serious skin reactions are mentioned in the source, including Stevens-Johnson syndrome and toxic epidermal necrolysis.

If a rash or other allergic-type reaction appears, urgent medical assessment is important.

Liver and kidney impairment

The source advises caution in both liver failure and renal failure.

It also states that liver function tests may be needed during the early stages of treatment, and that dose reduction may be required in liver impairment.

For kidney failure, the source gives specific dose-adjustment guidance and notes special handling for dialysis. Because these decisions depend on the individual patient, they should be confirmed by the prescribing clinician or pharmacist.

Drug interactions listed in the source

Allopurinol may interact with several medicines. The original content lists the following:

  • 6-mercaptopurine, azathioprine, adenine arabinoside, and cyclosporine: increased action and toxicity
  • Theophylline, warfarin, and coumarin anticoagulants: increased effects
  • Ampicillin/amoxicillin: increased frequency of skin rash
  • Probenecid and high doses of salicylates: decreased effect
  • Didanosine: increased plasma exposure

Always review your full medicine list, including over-the-counter products and supplements, with a healthcare professional.

Pregnancy and breastfeeding

The source says there is no human experience in pregnancy and that allopurinol should only be used when there is no safer alternative and when the disease itself poses risks to the mother or fetus.

For breastfeeding, the source says use is not recommended because allopurinol and its metabolites occur in human milk and may cause adverse reactions in infants.

Driving and daily activities

The source notes that drowsiness, vertigo, and ataxia have been reported. Until you know how the medicine affects you, caution is advised with driving, machinery, or other hazardous activities.

Possible side effects mentioned in the source

The original content lists the following adverse reactions:

  • Rash
  • Increased thyroid stimulating hormone
  • Very rare blood-related reactions such as agranulocytosis, thrombocytopenia, and aplastic anemia, especially in renal and/or hepatic insufficiency

Any new or worsening symptom should be discussed with a healthcare professional.

FAQ about allopurinol

▸ What is allopurinol mainly used for?

The source content describes allopurinol as a medicine used for gout and other conditions linked to high uric acid or urate deposition.

▸ How does allopurinol lower uric acid?

It inhibits xanthine oxidase, an enzyme involved in making uric acid.

▸ Can allopurinol cause a rash?

Yes. Rash is listed in the source, and hypersensitivity reactions are an important warning. A rash should be reviewed promptly by a healthcare professional.

▸ Is allopurinol used during an acute gout attack?

The source says treatment should not be started until the acute gout attack has passed.

▸ What should be checked before using allopurinol?

Kidney function, liver function, current medicines, pregnancy or breastfeeding status, and any history of hypersensitivity should be reviewed with a clinician or pharmacist.

▸ Where can I find official product information?

The FDA medication guide and the product leaflet are the best places to confirm approved uses, warnings, and dosing details.

Safety reminder

If you have been prescribed allopurinol, follow the official instructions for your specific product and speak with a healthcare professional if you notice rash, unusual symptoms, or any sign of an allergic reaction. Do not rely on this page for personal treatment decisions.

The original content cites FDA and USP-based ingredient information. Helpful reference links include:

Editorial note Active Ingredients Online Editorial Team This article is prepared as educational medicine information for general readers. It is written to support understanding of active ingredients, medicine uses, possible side effects, precautions and safety-related questions.
Published: June 12, 2019 Updated: August 17, 2026 Educational content

Medical disclaimer

This content is for educational purposes only. It should not be used as a substitute for professional medical advice, diagnosis or treatment. Always ask a doctor, pharmacist or qualified healthcare professional before starting, stopping or changing any medicine.

Sources and verification

The following sources or official references are listed to support verification of the medicine information discussed in this article.

Final note

Medicine information can change and may vary depending on country, product formulation, patient history and professional guidance. Always check official medicine information and ask a healthcare professional for personal medical questions.

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