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Pyrimethamine Side Effects

Medically reviewed by Drugs.com. Last updated on Apr 5, 2023.

Applies to pyrimethamine: oral tablet.

Serious side effects of Pyrimethamine

Along with its needed effects, pyrimethamine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking pyrimethamine:

Rare

Incidence not known

Other side effects of Pyrimethamine

Some side effects of pyrimethamine may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Incidence not known

For Healthcare Professionals

Applies to pyrimethamine: compounding powder, oral tablet.

General

Since this drug is coadministered with a sulfonamide, the manufacturer product information for the relevant sulfonamide should be consulted for sulfonamide-related side effects.[Ref]

Gastrointestinal

Very common (10% or more): Nausea, vomiting, diarrhea, colic

Uncommon (0.1% to 1%): Dry mouth, dry throat

Very rare (less than 0.01%): Buccal ulceration

Frequency not reported: Glossitis, atrophic glossitis[Ref]

Nervous system

Precipitation of a grand mal attack in a patient predisposed to epilepsy was reported; clinical significance was not established.[Ref]

Very common (10% or more): Headache

Common (1% to 10%): Dizziness

Very rare (less than 0.01%): Convulsions/seizures

Frequency not reported: Ataxia, tremors, precipitation of grand mal attack[Ref]

Hematologic

Very common (10% or more): Anemia

Common (1% to 10%): Thrombocytopenia, leukopenia

Very rare (less than 0.01%): Pancytopenia

Frequency not reported: Megaloblastic anemia, neutropenia, agranulocytosis[Ref]

Dermatologic

Very common (10% or more): Rash

Uncommon (0.1% to 1%): Abnormal skin pigmentation, dermatitis

Other

Uncommon (0.1% to 1%): Fever, malaise

Psychiatric

Insomnia was reported when this drug was given weekly at higher than recommended doses.

Uncommon (0.1% to 1%): Depression

Very rare (less than 0.01%): Insomnia

Respiratory

Rare (0.01% to 0.1%): Pulmonary eosinophilia

Very rare (less than 0.01%): Pneumonia with cellular and eosinophilic pulmonary infiltration[Ref]

Pneumonia with cellular and eosinophilic pulmonary infiltration was observed when this drug was administered once a week with sulfadoxine.[Ref]

Hypersensitivity

Frequency not reported: Hypersensitivity reactions (included erythema multiforme, Stevens-Johnson Syndrome, toxic epidermal necrolysis, Lyell's syndrome, hepatitis, anaphylaxis, pulmonary reactions, maculopapular rashes)[Ref]

Cardiovascular

Circulatory collapse was reported in patients treated with higher than recommended doses.[Ref]

Very rare (less than 0.01%): Circulatory collapse

Frequency not reported: Disorders of cardiac rhythm, arrhythmias[Ref]

Metabolic

Hyperphenylalaninemia was reported in neonates treated for congenital toxoplasmosis.[Ref]

Very rare (less than 0.01%): Hyperphenylalaninemia

Frequency not reported: Anorexia[Ref]

Genitourinary

Very rare (less than 0.01%): Hematuria

Oncologic

A 51-year-old female developed chronic granulocytic leukemia after taking this drug for 2 years for toxoplasmosis and a 56-year-old patient developed reticulum cell sarcoma after taking this drug for 14 months for toxoplasmosis.[Ref]

Frequency not reported: Chronic granulocytic leukemia, reticulum cell sarcoma[Ref]

References

1. Cerner Multum, Inc. UK Summary of Product Characteristics.

2. Cerner Multum, Inc. Australian Product Information.

3. Product Information. Daraprim (pyrimethamine). Glaxo Wellcome. 2001;PROD.

4. Ree GH. Chemoprophylaxis of malaria in Africa. Br Med J (Clin Res Ed). 1983;286:562.

5. Phillips-Howard PA, West LJ. Serious adverse drug reactions to pyrimethamine-sulphadoxine pyrimethamine-dapsone and to amodiaquine in Britain. J R Soc Med. 1990;83:82-5.

6. Olsen VV, Loft S, Christensen KD. Serious reactions during malaria prophylaxis with pyrimethamine- sulfadoxine. Lancet. 1982;2:994.

7. Nicholls MD, Concannon AJ. Maloprim-induced agranulocytosis and red-cell aplasia. Med J Aust. 1982;2:564-6.

8. Booth F, Barker LC, Barton CJ, Naik RB. Agranulocytosis during malaria prophylaxis with Maloprim (pyrimethamine and dapsone). Postgrad Med J. 1984;60:566-7.

9. Bowcock SJ, Linch DC, Machin SJ, Stewart JW. Pyrimethamine in the myeloproliferative disorders: a forgotten treatment? Clin Lab Haematol. 1987;9:129-36.

10. Whitehead S. Agranulocytosis associated with maloprim. Br Med J (Clin Res Ed). 1983;286:1515.

11. Iaccheri B, Fiore T, Papadaki T, et al. Adverse drug reactions to treatments for ocular toxoplasmosis: A retrospective chart review. Clin Ther. 2008;30:2069-74.

12. Zitelli BJ, Alexander J, Taylor S, Miller KD, Howrie DL, Kuritsky JN, Perez TH, Van Thiel DH. Fatal hepatic necrosis due to pyrimethamine-sulfadoxine (Fansidar). Ann Intern Med. 1987;106:393-5.

13. Davidson AC, Bateman C, Shovlin C, Marrinan M, Burton GH, Cameron IR. Pulmonary toxicity of malaria prophylaxis. BMJ. 1988;297:1240-1.

14. Selby CD, Ladusans EJ, Smith PG. Fatal multisystemic toxicity associated with prophylaxis with pyrimethamine and sulfadoxine (Fansidar). Br Med J (Clin Res Ed). 1985;290:113-4.

15. Svanbom M, Rombo L, Gustafsson L. Unusual pulmonary reaction during short term prophylaxis with pyrimethamine-sulfadoxine (Fansidar). Br Med J (Clin Res Ed). 1984;288:1876.

16. Whitfield D. Presumptive fatality due to pyrimethamine-sulfadoxine. Lancet. 1982;2:1272.

17. Phillips-Howard PA, Behrens RH, Dunlop J. Stevens-Johnson syndrome due to pyrimethamine/sulfadoxine during presumptive self-therapy of malaria. Lancet. 1989;2:803-4.

18. Fansidar-associated fatal reaction in an HIV-infected man. MMWR Morb Mortal Wkly Rep. 1988;37:571-2.

19. Hornstein OP, Ruprecht KW. Fansidar-induced Stevens-Johnson Syndrome. N Engl J Med. 1982;307:1529-30.

20. Jeffrey RF. Transient lupus anticoagulant and fansidar therapy. Postgrad Med J. 1986;62:893-4.

21. Adams SJ, Broadbent J, Clayden LM, Ridley CM. Erythema multiforme (Stevens-Johnson) precipitated by Fansidar. Postgrad Med J. 1985;61:263-4.

22. McCormack D, Morgan WK. Fansidar hypersensitivity pneumonitis. Br J Dis Chest. 1987;81:194-6.

23. Ward DJ, Krzeminska EC, Tanner NS. Treatment of toxic epidermal necrolysis and a review of six cases. Burns. 1990;16:97-104.

24. Ortel B, Sivayathorn A, Honigsmann H. An unusual combination of phototoxicity and Stevens-Johnson syndrome due to antimalarial therapy. Dermatologica. 1989;178:39-42.

25. Bamber MG, Elder AT, Gray JA, Minns RA. Fatal Stevens-Johnson syndrome associated with Fansidar and chloroquine. J Infect. 1986;13:31-3.

26. Pang JA. Non-cardiogenic pulmonary oedema associated with pyrimethamine. Respir Med. 1989;83:247-8.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.