- Antimicrobial that inhibits the reduction of dihydrofolic to tetrahydrofolic acid
- Indications include toxoplasmosis and malaria
- Major adverse effects is bone marrow suppression, so need to monitor CBC
- Pancytopenia, which is reversible with leucovorin
- GI intolerance
- Other: rash, hepatitis, headache, dizziness, insomnia
