Brand Names:

Drug Type: Antiprotozoal, Dewormer, Antimalarial, Antiparasitic


Pyrimethamine is an antiparasitic drug used against Toxoplasma gondii (Toxoplasmosis), Atoxoplasma, and Sarcocystis (Sarcocystosis). It may be effective for Leucocytozoon.

Pyrimethamine is a thiamine (vitamin B1) antagonist, meaning that the side effect of taking this drug, is that similar to amprolium, it reduces the amount of thiamine in the body.

Warning: Overdose may cause liver damage.
  • 0.5 mg/kg PO q12 x 30 days
  • Decreases thiamine levels, and can result in a thiamine deficiency-like status.