trimethoprim

noun

tri·​meth·​o·​prim trī-ˈme-thə-ˌprim 

: a synthetic antibacterial and antimalarial drug C₁₄H₁₈N₄O₃ used alone or in combination with sulfamethoxazole

Examples of trimethoprim in a Sentence

Recent Examples on the Web

An antibiotic, trimethoprim-sulfamethoxazole (TMP-SMX), may be prescribed if necessary. — Alison Fox, Travel + Leisure, 30 July 2026

He was prescribed Bactrim, a sulfamethoxazole-trimethoprim antibiotic commonly used to treat Cyclosporiasis, and said his symptoms improved within several hours of taking the first pill. — Janelle Mella, Charlotte Observer, 21 July 2026

Cyclospora can be treated with the combination antibiotic trimethoprim-sulfamethoxazole, also known as Bactrim, Septra or Cotrim. — Cindy Krischer Goodman, Sun Sentinel, 17 July 2026

Sulfamethoxazole and trimethoprim are types of antibiotics used to treat bacterial infections, according to the Cleveland Clinic. — Chad Murphy, USA Today, 14 July 2026

Word History

Etymology

tri- + meth- + -prim (by shortening & alteration from pyrimidine)

First Known Use

1964, in the meaning defined above

Medical Definition

trimethoprim

noun

tri·​meth·​o·​prim trī-ˈmeth-ə-ˌprim 

: a synthetic antibacterial drug C₁₄H₁₈N₄O₃ used alone especially to treat urinary tract infections and Pneumocystis carinii pneumonia and in combination with sulfamethoxazole to treat these as well as other infections (as shigellosis or acute otitis media) see bactrim