MSD Manual

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Trimethoprim and Sulfamethoxazole

Trimethoprim and Sulfamethoxazole

Drug

Common Uses

Some Side Effects

Trimethoprim*

Trimethoprim/sulfamethoxazole (TMP/SMX)

Bladder infections in women

Nausea, vomiting, and diarrhea

Crystals in urine (rare)

A decrease in white blood cell and platelet counts

Sensitivity to sunlight

Possibly increased tendency to bleed if used with warfarin

Kidney failure in people who have kidneys that are not functioning well

* Trimethoprim has side effects similar to those of sulfamethoxazole, but they are less common.