How long should this medication be taken for? ## What has your doctor advised? Daraprim contains the active ingredient Pyrimethamine, which is used to treat protozoal infections and the dosag can vary, depending on how severe the infection is. For instance, it can start with a range anywhere from 50 to 75mgs a day, coupled with other medications and can be taken for a span ranging anywhere from 1 to 3 weeks.