What is pyrimethamine?
Pyrimethamine is an antiparasitic prescription medicine approved by the U.S.(FDA) for the treatment of Toxoplasma gondii ( ). Pyrimethamine is usually used together with a sulfonamide (sulfa medicine) to treat toxoplasmosis.
Toxoplasmosis of the brain (also called Toxoplasma gondii What is an Opportunistic Infection? fact sheet.) is an (OI) of HIV. An OI is an infection that occurs more frequently or is more severe in people with weakened immune systems—such as people with HIV—than in people with healthy immune systems. To learn more about OIs, read the HIVinfo
How is pyrimethamine used in people with HIV?
The Guidelines for the Prevention and Treatment of Opportunistic Infections in HIV-Infected Adults and Adolescents include recommendations on the uses of pyrimethamine in people with HIV.
Using a medicine as indicated on the medicine label is called; using the medicine in a different way is called . Off-label use, for example, can include using a drug for a different disease or medical condition. Good medical practice and the best interests of a patient sometimes require that a medicine be used off-label.
The guidelines include recommendations on the following uses of pyrimethamine:On-label use:
- Treat Toxoplasma gondii encephalitis
- Treat isosporiasis (also called )
- Pneumocystis Jirovecii (PCP) from occurring the first time and from recurring
- Toxoplasma gondii encephalitis from occurring the first time and from recurring
- Isosporiasis from recurring
The above list may not include all of the HIV-related uses of pyrimethamine recommended in the guidelines. Some recommended uses, such as uses in certain rare circumstances, may have been omitted.
What should I tell my health care provider before taking pyrimethamine?
Before taking pyrimethamine, tell your health care provider:
- If you are allergic to pyrimethamine, sulfonamides (sulfa medicines), or any other medicines.
- About any medical conditions you have or have had.
- About anything that could affect your ability to take medicines, such as difficulty swallowing or remembering to take tablets.
- If you are pregnant or plan to become pregnant. Whether pyrimethamine can harm an unborn baby is unknown. Pyrimethamine should be used during pregnancy only if the potential benefits outweigh the risks. Talk to your health care provider about possible risks with taking pyrimethamine when pregnant.
- If you are breastfeeding or plan to breastfeed. Do not breastfeed if you have HIV.
- About other prescription and nonprescription medicines, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Pyrimethamine may affect the way other medicines or products work, and other medicines or products may affect how pyrimethamine works. Ask your health care provider if there are interactions between pyrimethamine and the other medicines you take.
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.
How should I take pyrimethamine?
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.
How should pyrimethamine be stored?
- Store pyrimethamine tablets in a dry place between 59°F and 77°F (15°C to 25°C).
- Keep pyrimethamine in the container that it came in and keep the container tightly closed. Protect pyrimethamine tablets from light.
- Do not use pyrimethamine if the original seal over the container opening is broken or missing.
- Throw away pyrimethamine that is no longer needed or expired (out of date). Follow FDA guidelines on how to safely dispose of unused medicine.
- Keep pyrimethamine and all medicines out of reach of children.
Where can I find more information about pyrimethamine?
More information about pyrimethamine is available:
- Recommendations on the HIV-related uses of pyrimethamine, from the Guidelines for the Prevention and Treatment of Opportunistic Infections in HIV-Infected Adults and Adolescents, prepared by the , the , and the HIV Medicine Association of the Diseases Society of America
- Pyrimethamine-related research studies, from
The above Patient Version drug summary is based on the following FDA label(s): Tablet.
Last Reviewed: December 31, 2018