Zyloprim Side Effects Center

Last updated on RxList: 8/29/2022
Zyloprim Side Effects Center

Medical Editor: John P. Cunha, DO, FACOEP

What Is Zyloprim?

Zyloprim (allopurinol) is a xanthine oxidase inhibitor that reduces the production of uric acid. Zyloprim is used to prevent gout attacks by reducing uric acid production; high levels of uric acid may cause gout or kidney stones. Zyloprim is available as a generic termed allopurinol.

What Are Side Effects of Zyloprim?

Side effects of Zyloprim include:

Tell your doctor if you experience rare but very serious side effects of Zyloprim including:

  • numbness or tingling of arms or legs,
  • easy bleeding or bruising,
  • signs of infection (e.g., fever, persistent sore throat),
  • unusual tiredness,
  • painful or bloody urination,
  • change in the amount of urine,
  • yellowing eyes or skin,
  • severe stomach or abdominal pain,
  • persistent nausea or vomiting,
  • dark urine,
  • unusual weight loss,
  • eye pain, or
  • vision changes.

Seek medical care or call 911 at once if you have the following serious side effects:

  • Serious eye symptoms such as sudden vision loss, blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights;
  • Serious heart symptoms such as fast, irregular, or pounding heartbeats; fluttering in your chest; shortness of breath; and sudden dizziness, lightheartedness, or passing out;
  • Severe headache, confusion, slurred speech, arm or leg weakness, trouble walking, loss of coordination, feeling unsteady, very stiff muscles, high fever, profuse sweating, or tremors.

This document does not contain all possible side effects and others may occur. Check with your physician for additional information about side effects.

Dosage for Zyloprim?

Zyloprim is available in 100 and 300 mg strength tablets. The usual doses start at 200 - 300 mg per day; dosage for children with hyperuricemia under 6 years old is 150 mg per day. Zyloprim is usually recommended to be taken after a meal.

What Drugs, Substances, or Supplements Interact with Zyloprim?

Zyloprim may interact with azathioprine, chlorpropamide, cyclosporine, mercaptopurine, antibiotics, blood thinners, or diuretics (water pills). Tell your doctor all medications and supplements you use.

Zyloprim During Pregnancy and Breastfeeding

Tell your doctor if you are pregnant or plan to become pregnant while using Zyloprim; it is unknown if Zyloprim will harm a fetus. Zyloprim passes into breast milk and may harm a nursing baby. Consult your doctor before breastfeeding.

Additional Information

Our Zyloprim Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

QUESTION

Gout is a form of arthritis. See Answer
Zyloprim Consumer Information

Stop using this medicine and get emergency medical help if you have signs of an allergic reaction (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Seek medical treatment if you have a serious drug reaction that can affect many parts of your body. Symptoms may include: skin rash, fever, swollen glands, muscle aches, severe weakness, unusual bruising, or yellowing of your skin or eyes.

Stop using allopurinol and call your doctor at once if you have:

  • any skin rash, no matter how mild;
  • painful urination, blood in the urine;
  • little or no urination;
  • easy bruising, unusual bleeding;
  • numbness, tingling, burning pain;
  • worsening gout symptoms; or
  • liver problems--loss of appetite, weight loss, stomach pain (upper right side), itching, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).

Common side effects may include:

  • an increase in gout attacks when you first starting taking allopurinol oral;
  • rash;
  • drowsiness;
  • fever, chills;
  • abnormal liver function tests;
  • nausea, diarrhea; or
  • joint pain.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

SLIDESHOW

Gout Attack Symptoms, Causes, Treatment, and Diet See Slideshow
Zyloprim Professional Information

SIDE EFFECTS

Data upon which the following estimates of incidence of adverse reactions are made are derived from experiences reported in the literature, unpublished clinical trials and voluntary reports since marketing of ZYLOPRIM (allopurinol) began. Past experience suggested that the most frequent event following the initiation of allopurinol treatment was an increase in acute attacks of gout (average 6% in early studies). An analysis of current usage suggests that the incidence of acute gouty attacks has diminished to less than 1%. The explanation for this decrease has not been determined but may be due in part to initiating therapy more gradually (see PRECAUTIONS and DOSAGE AND ADMINISTRATION).

The most frequent adverse reaction to ZYLOPRIM is skin rash. Skin reactions can be severe and sometimes fatal. Therefore, treatment with ZYLOPRIM should be discontinued immediately if a rash develops (see WARNINGS). Some patients with the most severe reaction also had fever, chills, arthralgias, cholestatic jaundice, eosinophilia and mild leukocytosis or leukopenia. Among 55 patients with gout treated with ZYLOPRIM for 3 to 34 months (average greater than 1 year) and followed prospectively, Rundles observed that 3% of patients developed a type of drug reaction which was predominantly a pruritic maculopapular skin eruption, sometimes scaly or exfoliative. However, with current usage, skin reactions have been observed less frequently than 1%. The explanation for this decrease is not obvious. The incidence of skin rash may be increased in the presence of renal insufficiency. The frequency of skin rash among patients receiving ampicillin or amoxicillin concurrently with ZYLOPRIM has been reported to be increased (see PRECAUTIONS).

Drug rash with eosinophilia and systemic symptoms (DRESS) syndrome or drug hypersensitivity syndrome (DHS) has been reported in association with allopurinol use. The syndrome includes many of the severe reactions described above, and is potentially life-threatening and fatal. The syndrome is often characterized by fever, severe and profuse skin rash, elevated leukocyte counts and in particular, elevated eosinophil counts, lymphadenopathy, and multi-organ pathologies. Systemic symptoms often included, but were not limited to, the hepatic and renal systems. Symptoms involving the cardiac, gastrointestinal, lymphatic, pulmonary, and ophthalmic systems were also reported as occurring as part of the syndrome. It has been reported that symptoms may develop in approximately 1 week from initiating allopurinol therapy, but longer latency periods have also been reported.

To report SUSPECTED ADVERSE REACTIONS, contact Casper Pharma LLC at 1-844-5­CASPER (1-844-522-7737) or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

Most Common Reactions* Probably Causally Related

Gastrointestinal: Diarrhea, nausea, alkaline phosphatase increase, SGOT/SGPT increase.

Metabolic and Nutritional: Acute attacks of gout.

Skin and Appendages: Rash, maculopapular rash.

*Early clinical studies and incidence rates from early clinical experience with ZYLOPRIM suggested that these adverse reactions were found to occur at a rate of greater than 1%. The most frequent event observed was acute attacks of gout following the initiation of therapy. Analyses of current usage suggest that the incidence of these adverse reactions is now less than 1%. The explanation for this decrease has not been determined, but it may be due to following recommended usage (see ADVERSE REACTIONS introduction, INDICATIONS AND USAGE, PRECAUTIONS, and DOSAGE AND ADMINISTRATION).

Incidence Less Than 1% Probably Causally Related

Body As a Whole: Ecchymosis, fever, headache.

Cardiovascular: Necrotizing angiitis, vasculitis.

Gastrointestinal: Hepatic necrosis, granulomatous hepatitis, hepatomegaly, hyperbilirubinemia, cholestatic jaundice, vomiting, intermittent abdominal pain, gastritis, dyspepsia.

Hemic and Lymphatic: Thrombocytopenia, eosinophilia, leukocytosis, leukopenia.

Musculoskeletal: Myopathy, arthralgias.

Nervous: Peripheral neuropathy, neuritis, paresthesia, somnolence.

Respiratory: Epistaxis.

Skin and Appendages: Erythema multiforme exudativum (Stevens-Johnson syndrome), toxic epidermal necrolysis (Lyell's syndrome), hypersensitivity vasculitis, purpura, vesicular bullous dermatitis, exfoliative dermatitis, eczematoid dermatitis, pruritus, urticaria, alopecia, onycholysis, lichen planus.

Special Senses: Taste loss/perversion.

Urogenital: Renal failure, uremia (see PRECAUTIONS).

Incidence Less Than 1% Causal Relationship Unknown

Body As a Whole: Malaise.

Cardiovascular: Pericarditis, peripheral vascular disease, thrombophlebitis, bradycardia, vasodilation.

Endocrine: Infertility (male), hypercalcemia, gynecomastia (male).

Gastrointestinal: Hemorrhagic pancreatitis, gastrointestinal bleeding, stomatitis, salivary gland swelling, hyperlipidemia, tongue edema, anorexia.

Hemic and Lymphatic: Aplastic anemia, agranulocytosis, eosinophilic fibrohistiocytic lesion of bone marrow, pancytopenia, prothrombin decrease, anemia, hemolytic anemia, reticulocytosis, lymphadenopathy, lymphocytosis.

Musculoskeletal: Myalgia.

Nervous: Optic neuritis, confusion, dizziness, vertigo, foot drop, decrease in libido, depression, amnesia, tinnitus, asthenia, insomnia.

Respiratory: Bronchospasm, asthma, pharyngitis, rhinitis.

Skin and Appendages: Furunculosis, facial edema, sweating, skin edema.

Special Senses: Cataracts, macular retinitis, iritis, conjunctivitis, amblyopia.

Urogenital: Nephritis, impotence, primary hematuria, albuminuria.

DRUG INTERACTIONS

In patients receiving mercaptopurine or IMURAN (azathioprine), the concomitant administration of 300 to 600 mg of ZYLOPRIM per day will require a reduction in dose to approximately one third to one fourth of the usual dose of mercaptopurine or azathioprine. Subsequent adjustment of doses of mercaptopurine or azathioprine should be made on the basis of therapeutic response and the appearance of toxic effects (see CLINICAL PHARMACOLOGY).

It has been reported that ZYLOPRIM prolongs the half-life of the anticoagulant, dicumarol. The clinical basis of this drug interaction has not been established but should be noted when ZYLOPRIM is given to patients already on dicumarol therapy.

Since the excretion of oxipurinol is similar to that of urate, uricosuric agents, which increase the excretion of urate, are also likely to increase the excretion of oxipurinol and thus lower the degree of inhibition of xanthine oxidase. The concomitant administration of uricosuric agents and ZYLOPRIM has been associated with a decrease in the excretion of oxypurines (hypoxanthine and xanthine) and an increase in urinary uric acid excretion compared with that observed with ZYLOPRIM alone. Although clinical evidence to date has not demonstrated renal precipitation of oxypurines in patients either on ZYLOPRIM alone or in combination with uricosuric agents, the possibility should be kept in mind.

The reports that the concomitant use of ZYLOPRIM and thiazide diuretics may contribute to the enhancement of allopurinol toxicity in some patients have been reviewed in an attempt to establish a cause-and-effect relationship and a mechanism of causation. Review of these case reports indicates that the patients were mainly receiving thiazide diuretics for hypertension and that tests to rule out decreased renal function secondary to hypertensive nephropathy were not often performed. In those patients in whom renal insufficiency was documented, however, the recommendation to lower the dose of ZYLOPRIM was not followed. Although a causal mechanism and a cause-and-effect relationship have not been established, current evidence suggests that renal function should be monitored in patients on thiazide diuretics and ZYLOPRIM even in the absence of renal failure, and dosage levels should be even more conservatively adjusted in those patients on such combined therapy if diminished renal function is detected.

An increase in the frequency of skin rash has been reported among patients receiving ampicillin or amoxicillin concurrently with ZYLOPRIM compared to patients who are not receiving both drugs. The cause of the reported association has not been established.

Enhanced bone marrow suppression by cyclophosphamide and other cytotoxic agents has been reported among patients with neoplastic disease, except leukemia, in the presence of ZYLOPRIM. However, in a well-controlled study of patients with lymphoma on combination therapy, ZYLOPRIM did not increase the marrow toxicity of patients treated with cyclophosphamide, doxorubicin, bleomycin, procarbazine, and/or mechlorethamine.

Tolbutamide's conversion to inactive metabolites has been shown to be catalyzed by xanthine oxidase from rat liver. The clinical significance, if any, of these observations is unknown.

Chlorpropamide's plasma half-life may be prolonged by ZYLOPRIM, since ZYLOPRIM and chlorpropamide may compete for excretion in the renal tubule. The risk of hypoglycemia secondary to this mechanism may be increased if ZYLOPRIM and chlorpropamide are given concomitantly in the presence of renal insufficiency.

Rare reports indicate that cyclosporine levels may be increased during concomitant treatment with ZYLOPRIM. Monitoring of cyclosporine levels and possible adjustment of cyclosporine dosage should be considered when these drugs are co-administered.

Drug/Laboratory Test Interactions

ZYLOPRIM is not known to alter the accuracy of laboratory tests.

Read the entire FDA prescribing information for Zyloprim (Allopurinol)

© Zyloprim Patient Information is supplied by Cerner Multum, Inc. and Zyloprim Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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