Pyrimethamine: uses, dosing, side effects & brands
Pyrimethamine is a dihydrofolate reductase inhibitor antimalarial sold in the U.S. under 2 brand and generic names, for toxoplasmosis, falciparum malaria and aids-related opportunistic infections. Below: what the FDA label says, every product that contains it, what the pills look like, and its recall record.
Key facts
- Drug class
- Dihydrofolate Reductase Inhibitor Antimalarial
- Treats
- Toxoplasmosis, Falciparum Malaria and Aids-Related Opportunistic Infections
- Available as
- Tablet
- Sold as
- 2 products — Pyrimethamine and Daraprim
- Prescription?
- Prescription only
- Generic available?
- Yes
- What the pharmacy pays
- about $4110 for a 30-count supply — not your price
How pyrimethamine is dosed
From the FDA label for Pyrimethamine (application ANDA216983). Other pyrimethamine products — different forms, different strengths — are dosed differently. Follow the label for the one you were prescribed.
For Treatment of Toxoplasmosis: The dosage of pyrimethamine tablets for the treatment of toxoplasmosis must be carefully adjusted so as to provide maximum therapeutic effect and a minimum of side effects. At the dosage required, there is a marked variation in the tolerance to the drug. Young patients may tolerate higher doses than older individuals. Concurrent administration of folinic acid is strongly recommended in all patients. The adult starting dose is 50 to 75 mg of the drug daily, together with 1 to 4 g daily of a sulfonamide of the sulfapyrimidine type, e.g. sulfadoxine. This dosage is ordinarily continued for 1 to 3 weeks, depending on the response of the patient and tolerance to therapy. The dosage may then be reduced to about one half that previously given for each drug and continued for an additional 4 to 5 weeks. The pediatric dosage of pyrimethamine tablets is 1 mg/kg/day divided into 2 equal daily doses; after 2 to 4 days this dose may be reduced to one half and continued for approximately 1 month. The usual pediatric sulfonamide dosage is used in conjunction with pyrimethamine tablets.
Pyrimethamine side effects
Hypersensitivity reactions, occasionally severe (such as Stevens-Johnson syndrome, toxic epidermal necrolysis, erythema multiforme, and anaphylaxis), and hyperphenylalaninemia, can occur particularly when pyrimethamine is administered concomitantly with a sulfonamide. Consult the complete prescribing information for the relevant sulfonamide for sulfonamide-associated adverse events. With doses of pyrimethamine used for the treatment of toxoplasmosis, anorexia and vomiting may occur. Vomiting may be minimized by giving the medication with meals; it usually disappears promptly upon reduction of dosage. Doses used in toxoplasmosis may produce megaloblastic anemia, leukopenia, thrombocytopenia, pancytopenia, neutropenia, atrophic glossitis, hematuria, and disorders of cardiac rhythm. Hematologic effects, however, may also occur at low doses in certain individuals (see PRECAUTIONS ; General ). Pulmonary eosinophilia has been reported rarely.
Who shouldn’t take pyrimethamine
Use of pyrimethamine tablets are contraindicated in patients with known hypersensitivity to pyrimethamine or to any component of the formulation. Use of the drug is also contraindicated in patients with documented megaloblastic anemia due to folate deficiency.
Pyrimethamine drug interactions
Pyrimethamine may be used with sulfonamides, quinine and other antimalarials, and with other antibiotics. However, the concomitant use of other antifolic drugs or agents associated with myelosuppression including sulfonamides or trimethoprim-sulfamethoxazole combinations, proguanil, zidovudine, or cytostatic agents (e.g., methotrexate), while the patient is receiving pyrimethamine, may increase the risk of bone marrow suppression. If signs of folate deficiency develop, pyrimethamine should be discontinued. Folinic acid (leucovorin) should be administered until normal hematopoiesis is restored (see WARNINGS ). Mild hepatotoxicity has been reported in some patients when lorazepam and pyrimethamine were administered concomitantly.
Every pyrimethamine product we track (2)
Same active ingredient — different manufacturer, form, price and FDA recall record. That last one is what our independent score measures.
| # | Drug | Rating | Type | Form | Generic? | Pharmacy pays | |
|---|---|---|---|---|---|---|---|
| 1 | 68/100 | Prescription | Tablet | Generic | $4110 | View → | |
| 2 | Not yet rated | Prescription | Tablet | Generic | $4110 | View → |
What pyrimethamine pills look like
Imprint codes, colour and shape from the FDA’s labelling data. Match the imprint on your pill — or search any imprint.
| Imprint | Strength | Colour | Shape | Maker |
|---|---|---|---|---|
| L;25 | 25 mg | white | round | — |
| L;25 | 25 mg | white | round | — |
| DARAPRIM;A3A | 25 mg | white | round | — |
Pyrimethamine and breastfeeding
From LactMed, the US National Library of Medicine’s Drugs and Lactation Database — quoted, not rewritten.
Full LactMed record for pyrimethamine: levels in milk, effects in breastfed infants, and the drugs it would consider insteadNo adverse reactions in breastfed infants have been reported during maternal pyrimethamine use. It is acceptable to use in nursing mothers. In HIV-infected women, elevated viral HIV loads in milk were decreased after treatment with chloroquine to a greater extent than other women who were treated with the combination of sulfadoxine and pyrimethamine. It has been suggested that maternal pyrimethamine clearance might be increased during lactation, but data are insufficient to make a definitive conclusion.
National Institute of Child Health and Human Development, record revised May 15, 2025. LactMed states its information is not a substitute for professional judgement.
What people report to the FDA about pyrimethamine
The FDA Adverse Event Reporting System (FAERS) collects reports from patients and clinicians. It holds 1,186 reports naming pyrimethamine, and the FDA flagged 97% of those reports as serious. The effects reported most often — leaving out reports about overdose, misuse or the condition being treated, which dominate the raw list for common medicines:
- pancytopenia118 reports
- neutropenia88 reports
- pyrexia70 reports
- small for dates baby57 reports
- cerebral toxoplasmosis54 reports
- thrombocytopenia50 reports
- vomiting46 reports
- diarrhoea45 reports
Read these as a signal, not a rate. A report does not mean pyrimethamine caused the effect — anyone can file one, and many describe people taking several medicines for several conditions. Crucially there is no denominator: FAERS does not record how many people took the drug, so these counts cannot be turned into “X% of patients” — a bigger number often just means a more widely used or more talked-about drug. Duplicates exist, and publicity drives reporting. For what is actually established, read the FDA label section above.
Source: openFDA drug/event (FAERS), retrieved August 26, 2026.
Related calculators
Frequently asked questions
What is pyrimethamine?
Pyrimethamine is a dihydrofolate reductase inhibitor antimalarial used to treat Toxoplasmosis, Falciparum Malaria, Aids-Related Opportunistic Infections.
What kind of drug is pyrimethamine?
The FDA classifies pyrimethamine as a dihydrofolate reductase inhibitor antimalarial. If you are checking whether it is safe to combine with something else, the class is what matters — two drugs from the same class usually should not be stacked.
Can you take pyrimethamine with other medicines?
It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run pyrimethamine against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.
What brand names is pyrimethamine sold under?
We track 2 pyrimethamine-containing products in the U.S.: Pyrimethamine and Daraprim. They are the same active ingredient; they differ in form, manufacturer, price and FDA recall record.
What forms does pyrimethamine come in?
Across the brands we track, pyrimethamine is currently marketed as tablet, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.
Is there a generic pyrimethamine?
Yes. Our catalog lists 1 generic pyrimethamine product alongside the brand versions. A generic has the same active ingredient and must meet the FDA's bioequivalence standard; it usually costs less. Ask your pharmacist which one your plan covers.
Cite this page
- APA
- pharmaranks. (2026, July 24). Pyrimethamine: uses, dosing, side effects & brands. https://pharmaranks.com/drugs/pyrimethamine
- MLA
- “Pyrimethamine: uses, dosing, side effects & brands.” pharmaranks, 24 July 2026, https://pharmaranks.com/drugs/pyrimethamine.
We summarise public FDA and NIH sources — for a clinical claim, cite the primary source we link to as well.
Sources: FDA openFDA drug label, National Drug Code Directory, and Enforcement (recall) database. This page reproduces public FDA data and is not medical advice. Dosing is set by your prescriber.
Read the full FDA label for pyrimethamine on DailyMed (NIH) ↗.