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Sulfamethoxazole / Trimethoprim

Sulfamethoxazole / Trimethoprim

Other Names: Bactrim, Bactrim DS, SMX-TMP, Septra, Sulfamethoprim, Sulfamethoprim-DS, Sulfatrim, TMP-SMX Drug Class: Opportunistic Infections and Coinfections
What is sulfamethoxazole/trimethoprim?

What is sulfamethoxazole/trimethoprim?

Sulfamethoxazole/trimethoprim is an antibacterial prescription medicine approved by the U.S. Food and Drug Administration (FDA) to treat certain infections, such as:

  • Acute exacerbations (worsening) of chronic bronchitis
  • Urinary tract and acute ear infections
  • Shigellosis
  • Diarrhea
  • Pneumocystis carinii pneumonia (PCP)

Sulfamethoxazole/trimethoprim is also FDA-approved to prevent PCP in people who are immunosuppressed and are at risk of developing PCP.

Shigellosis and PCP are opportunistic infections (OIs) 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 AIDSinfo What is an Opportunistic Infection? fact sheet.

How is sulfamethoxazole/trimethoprim used in people with HIV?

How is sulfamethoxazole/trimethoprim used in people with HIV?

The Guidelines for the Prevention and Treatment of Opportunistic Infections in HIV-Infected Adults and Adolescents include recommendations on uses of sulfamethoxazole/trimethoprim in people with HIV.

Using a medicine as indicated on the medicine label is called on-label use; using the medicine in a different way is called off-label use. 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 sulfamethoxazole/trimethoprim:

On-label uses:

Off-label uses:
  • Prevent:
    • Toxoplasmosis (used for both primary and secondary prophylaxis)
    • Isosporiasis (used for secondary prophylaxis)
The above list may not include all of the HIV-related uses of sulfamethoxazole/trimethoprim 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 sulfamethoxazole/trimethoprim?

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, diabetes or liver 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 intravenous 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 kernicterus. Sulfamethoxazole/trimethoprim should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Talk to your health care provider about possible risks with taking sulfamethoxazole/trimethoprim 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. 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?

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?

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?

Where can I find more information about sulfamethoxazole/trimethoprim?

More information about sulfamethoxazole/trimethoprim is available:

The above Patient Version drug summary is based on the following FDA label(s): Injection; Suspension; Tablet, tablet (double strength).

Last Reviewed: January 10, 2019