tri·​meth·​o·​prim trī-ˈme-thə-ˌprim How to pronounce trimethoprim (audio)
: a synthetic antibacterial and antimalarial drug C14H18N4O3 used alone or in combination with sulfamethoxazole

Example Sentences

Recent Examples on the Web Next came Macrobid, a combination treatment of trimethoprim and sulfamethoxazole. Natalie Ma, STAT, 31 Oct. 2021 Antibiotics are used to treat donovanosis, including azithromycin, doxycycline, ciprofloxacin, erythromycin and trimethoprim-sulfamethoxazole. Scott Gleeson, USA TODAY, 26 Oct. 2021 Treatment of nocardia of the lung in people with normal immune systems usually involves trimethoprim and sulfamethoxazole; since that seemed not to do well for you, minocycline is a reasonable option. Dr. Keith Roach, oregonlive, 1 July 2021 Seeing a doctor is important not only because the infection can be diagnosed by stool exams, but also because the parasite is treatable with trimethoprim-sulfamethoxazole, an antibiotic combination, according to Dr. Sears. Colleen Murphy,, 29 June 2021 The usual treatment is trimethoprim/sulfamethoxazole, an antibiotic combination. Sarah Jacoby, SELF, 9 July 2018 And, of those patients, nearly 35 percent filled a prescription for nitrofurantoin and nearly 8 percent filled a prescription for trimethoprim-sulfamethoxazole, per the CDC data. Korin Miller, SELF, 18 Jan. 2018 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'trimethoprim.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Word History


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

First Known Use

1964, in the meaning defined above

Time Traveler
The first known use of trimethoprim was in 1964

Dictionary Entries Near trimethoprim

Cite this Entry

“Trimethoprim.” Dictionary, Merriam-Webster, Accessed 30 Nov. 2022.

Medical Definition



tri·​meth·​o·​prim trī-ˈmeth-ə-ˌprim How to pronounce trimethoprim (audio)
: 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

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