Trimethoprim and Sulfamethoxazole

ByBrian J. Werth, PharmD, University of Washington School of Pharmacy
Reviewed/Revised May 2024
VIEW PROFESSIONAL VERSION

sulfonamide antibiotic).

Trimethoprim and the combination of trimethoprim and sulfamethoxazole (TMP/SMX) are effective against many gram-positive bacteria and gram-negative bacteria, including susceptible bacteria that are resistant to other antibiotics, such as methicillin-resistant Staphylococcus aureus (MRSA) and some protozoa (Cyclospora and Cystoisospora) and fungi (Pneumocystis

Table

(See also Overview of Antibiotics.)

Use During Pregnancy and Breastfeeding

neural tube defects), such as spina bifida, are a risk. The combination of trimethoprim/sulfamethoxazole should not be used during pregnancy or in newborns because it may cause jaundice and increases the risk of brain damage (kernicterus) in the fetus or in the newborn. (See also Safety of Medications During Pregnancy.)

Use of trimethoprim/sulfamethoxazole during breastfeeding is usually discouraged because sulfamethoxazole passes into breast milk. Use of trimethoprim during breastfeeding is generally considered acceptable. (See also Medication and Substance Use During Breastfeeding.)

Drugs Mentioned In This Article
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