This page contains brief details about the drug , it's indication, dosage & administaration, mechanism of action, related brands with strength, warnings and common side effects.

Background and Date of Approval

Pyrimethamine is an antiparasitic drug that belongs to the class of antiprotozoal agents. FDA approved the generic version on February 2020 to treat toxoplasmosis with other groups of antibiotics.

Mechanism of Action of undefined

Pyrimethamine is an antiprotozoal agent that binds to and reversibly inhibits the protozoal enzyme and selectively blocks its conversion, which is essential for DNA synthesis and cell proliferation.

Uses of undefined

Pyrimethamine is available as a tablet. It is used in combination with other antibiotics to treat blood infections caused by a parasite called toxoplasma. These infections can affect the brain and other parts of the body if your immune system is poor. This can be caused due to AIDS or HIV infection. It is also used to treat malarial infections.

undefined Drug administaration and Dosage available

It is an orally available prescription drug. It is an orally available prescription drug. Your doctor will decide the dose and duration of pyrimethamine based on the disease condition and other factors such as body weight and age. Always take this medicine as prescribed by your doctor. Take the tablet at the same time, with or without food. Do not break, chew, crush, or break the tablet. Swallow the whole tablet with a glass of water. 

Warnings, Precautions and Side Effects of undefined


This drug is indicated to cause severe anemia. Routine blood tests will be taken to monitor your complete blood counts. This medicine may cause a severe skin rash. Inform your physician if you develop any rashes, redness, or swelling in the skin after taking pyrimethamine. This medicine is not intended for pregnant and breastfeeding women.


Do not take pyrimethamine if you are allergic to pyrimethamine or any of the other ingredients or if you are pregnant or breastfeeding. This tablet is not recommended in children under five years of age. Inform your physician if you have kidney or liver problems, anemia, and seizures. This medicine will always be given to you with a vitamin supplement. Do not forget to take your vitamin supplements. 

Inform your healthcare provider about all your medicines, including prescription, over-the-counter, nutritional, and supplements and herbal products. Certain medications interact with pyrimethamine and reduce its effectiveness by causing undesirable side effects. 

Side Effects

The common side effects of pyrimethamine are nausea, vomiting, loss of appetite, and skin rash. Other serious side effects include severe skin reactions, and low platelet counts.

Word Of Advice

Store pyrimethamine below 30°C. Protect the medicine from light and excessive moisture. Keep the medicine out of reach of children and pets. If you forgot to take the tablet, take your next dose at the scheduled time. Do not take a double dose to make up for a forgotten dose. Take all of the medicine and complete the course of therapy even if you feel better after the first few doses. Do not take extra doses or medicine to make up for a missed dose. Inform your doctor if you drink alcohol. 

This medicine may make you bleed, bruise, or catch infections more easily. Take precautions to prevent the illness. Take this medicine as prescribed by your doctor. Take this medicine with food to decrease nausea and vomiting. Do not skip the medicine or change the dose without consulting the doctor. Common side effects like nausea, vomiting, and loss of appetite.

Frequently Asked Question


  1. Daraprim Tablets - Summary of Product Characteristics (SmPC) - (emc). Published February 2023. Accessed May 9, 2023.
  2. DARAPRIM ® (Pyrimethamine) 25-Mg Scored Tablets. Accessed May 9, 2023.
  3. Philip J. Rosenthal, Antiprotozoal Drugs, Lange’s Basic and Clinical Pharmacology, 14th Edition, 2018, 917-937.
  4. D.H. Dockrell, S. Sundar, B.J. Angus, R.P. Hobson, Infectious disease, Davidson’s Principles and Practice of Medicine, 22nd Edition, 2014, 293-386.


The drug information on this page is not a substitute for medical advice. It is meant for educational purposes only. For further details, consult your doctor about your medical condition to know if you can receive this treatment.