Pyrimethamine is an antiparasitic prescription medicine approved by the U.S. Food and Drug Administration(FDA) for the treatment of toxoplasmosis (infection caused by the parasite Toxoplasma gondii) and acute malaria. When used to treat these diseases, pyrimethamine is usually used together with a sulfonamide medicine. Pyrimethamine is also FDA-approved for the prevention of certain types of malaria.
Toxoplasmosis of the brain (also called Toxoplasma gondii encephalitis) and malaria are opportunistic infections. An opportunistic infection is an infection that occurs more frequently or is more severe in people with weakened immune systems—such as those infected with HIV—than in people with healthy immune systems. To learn more about opportunistic infections, read the AIDSinfo What is an Opportunistic Infection? fact sheet.
Pyrimethamine can also be used “off-label” to prevent and treat other opportunistic infections of HIV infection. “Off-label” use refers to use of an FDA-approved medicine in a manner different from that described on the medicine label. Good medical practice and the best interests of a patient sometimes require that a medicine be used “off-label.”
The Guidelines for the Prevention and Treatment of Opportunistic Infections in HIV-Infected Adults and Adolescents, prepared by the Centers for Disease Control and Prevention (CDC), the National Institutes of Health (NIH), and the HIV Medicine Association of the Infectious Diseases Society of America (IDSA-HIVMA), includes recommendations on the HIV-related uses of pyrimethamine to:
The above list may not include all of the HIV-related uses of pyrimethamine recommended in the Guidelines for the Prevention and Treatment of Opportunistic Infections in HIV-Infected Adults and Adolescents. Some recommended uses, such as uses in certain rare circumstances, may have been omitted.
Before taking pyrimethamine, tell your health care provider:
Ask your health care provider about possible side effects from pyrimethamine. Your health care provider will tell you what to do if you have side effects.
Take pyrimethamine according to your health care provider’s instructions. Your health care provider will tell you how much pyrimethamine to take and when to take it. Before you start pyrimethamine and each time you get a refill, read any printed information that comes with your medicine.
More information about pyrimethamine is available:
Last Reviewed: August 11, 2016