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Pyrimethamine oral

Important Note

The following information is intended to supplement, not substitute for, the expertise and judgment of your physician, pharmacist or other healthcare professional. It should not be construed to indicate that use of the drug is safe, appropriate, or effective for you. Consult your healthcare professional before using this drug.





This medication is used in the treatment and prevention of malaria or the treatment of toxoplasmosis (a parasitic infection). Pyrmethamine is often taken in combination with other antimalaria medication.

How To Use

Take this medication by mouth with food or meals as directed. For preventing malaria, this is usually taken once a week. For treatment of a malarial attack, this is taken once a day for 2 days, then given once a week. In the treatment of toxoplasmosis, this may be given once or twice a day for up to 5 weeks. Take this medication for the full time prescribed. Stopping therapy too soon may result in ineffective treatment.

Side Effects

Nausea, stomach upset or loss of appetite may occur especially the first several days as your body adjusts to the medication. Other effects reported include headache, lightheadedness, dry mouth, diarrhea, trouble sleeping. If any of these effects continue or become bothersome, inform your doctor. Notify your doctor if you develop a skin rash, sore throat, unusual bruising, pale skin, swelling of the tongue, depression, irregular heartbeat. Use caution driving or operating machinery if this medication makes you lightheaded. This medication may cause blood disorders. It is important that lab tests be done periodically while taking this medication to monitor for this. If you notice other effects not listed above, contact your doctor or pharmacist.


Tell your doctor if you have any: pre-existing kidney disease, liver disease, blood disorders, allergies. This medication should be used only if clearly needed during pregnancy. Discuss the risks and benefits with your doctor. This medication appears in breast milk. Consult your doctor before breast-feeding.

Drug Interactions

Tell your doctor of any over-the-counter or prescription medication you may take including: sulfa antibiotics, phenytoin, methotrexate. Do not start or stop any medicine without doctor or pharmacist approval.


If overdose is suspected, contact your local poison control center or emergency room immediately. Symptoms of overdose may include vomiting, temporary stop in breathing, fever, fast heartbeat, and seizures.


Laboratory tests will be done periodically while taking this medication to monitor its effects.

Missed Dose

If you miss a dose, take it as soon as remembered; do not take it if it is near the time for the next dose, instead, skip the missed dose and resume your usual dosing schedule. Do not "double-up" the dose to catch up.


Store at room temperature between 59 and 86 degrees F (15 to 30 degrees C) away from heat and light. Do not store in the bathroom.