What is sulfamethoxazole/trimethoprim?
Sulfamethoxazole/trimethoprim is an antibacterial prescription medicine approved by the U.S.(FDA) to treat certain infections, such as:
- Acute exacerbations (worsening) of chronic bronchitis
- Urinary tract and acute ear infections
- Pneumocystis jirovecii (PCP)
Sulfamethoxazole/trimethoprim is also FDA-approved to prevent PCP in people who are immunosuppressed and are at risk of developing PCP.
Shigellosis and community-acquired PCP are opportunistic infections (OIs) of HIV. An OI is an What is an Opportunistic Infection? fact sheet.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 sulfamethoxazole/trimethoprim used in people with HIV?
The Guidelines for the Prevention and Treatment of Opportunistic Infections in Adults and Adolescents with HIV include recommendations on the uses of sulfamethoxazole/trimethoprim in people with HIV to:Treat:
- Community-acquired PCP
- Certain bacterial infections, including shigellosis and salmonellosis (also known as infection)
- Isosporiasis (also called Isospora belli infection)
- Toxoplasma gondii (also called )
- Community-acquired PCP from occurring the first time (called ) and from recurring (called secondary or )
- Toxoplasmosis (used for both primary and secondary prophylaxis)
- Isosporiasis (used for secondary prophylaxis)
The recommended uses may not always be consistent with FDA-approved uses of sulfamethoxazole/trimethoprim. See the guidelines for complete information on recommended uses of sulfamethoxazole/trimethoprim in adults and adolescents with HIV. Some recommended uses, such as uses in certain rare circumstances, may have been omitted above.
What should I tell my health care provider before taking sulfamethoxazole/trimethoprim?
Before taking sulfamethoxazole/trimethoprim, tell your health care provider:
- If you are allergic to sulfonamides (including sulfamethoxazole), trimethoprim, or any other medicines.
- About any medical conditions you have or have had, for example, or problems.
- About anything that could affect your ability to take medicines, such as difficulty swallowing pills, difficulty remembering to take pills, or any health conditions that may prevent your use of medicines.
- If you are pregnant or plan to become pregnant. Sulfamethoxazole/trimethoprim should not be used by pregnant women because sulfonamides (including sulfamethoxazole) may cause . Sulfamethoxazole/trimethoprim should be used during pregnancy only if the potential benefit justifies the potential risk to the . Talk to your health care provider about the risks of taking sulfamethoxazole/trimethoprim during pregnancy.
- 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. Sulfamethoxazole/trimethoprim may affect the way other medicines or products work, and other medicines or products may affect how sulfamethoxazole/trimethoprim works. Ask your health care provider if there are interactions between sulfamethoxazole/trimethoprim and the other medicines you take.
Ask your health care provider about possible side effects from sulfamethoxazole/trimethoprim. Your health care provider will tell you what to do if you have side effects.
How should I take sulfamethoxazole/trimethoprim?
Take sulfamethoxazole/trimethoprim according to your health care provider’s instructions. Your health care provider will tell you how much sulfamethoxazole/trimethoprim to take and when to take it. Before you start sulfamethoxazole/trimethoprim and each time you get a refill, read any printed information that comes with your medicine.
How should sulfamethoxazole/trimethoprim be stored?
- Store sulfamethoxazole/trimethoprim oral suspension at room temperature, 68°F to 77°F (20°C to 25°C). Protect the oral suspension from light.
- Store sulfamethoxazole/trimethoprim tablets at room temperature, 68°F to 77°F (20°C to 25°C).
- Store sulfamethoxazole/trimethoprim injection solution at room temperature, 68°F to 77°F (20°C to 25°C). Do not refrigerate the injection solution.
- Do not use sulfamethoxazole/trimethoprim if the original seal of the container is broken or missing.
- Throw away sulfamethoxazole/trimethoprim that is no longer needed or expired (out of date). Follow FDA guidelines on how to safely dispose of unused medicine.
- Keep sulfamethoxazole/trimethoprim and all medicines out of reach of children.
Where can I find more information about sulfamethoxazole/trimethoprim?
More information about sulfamethoxazole/trimethoprim is available:
- Recommendations on the HIV-related uses of sulfamethoxazole/trimethoprim, from the Guidelines for the Prevention and Treatment of Opportunistic Infections in Adults and Adolescents with HIV, prepared by the , the , and the HIV Medicine Association of the Diseases Society of America
- Sulfamethoxazole/trimethoprim-related research studies, from
Last Reviewed: January 10, 2019