Merck Manual

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Trimethoprim and Sulfamethoxazole

Trimethoprim and Sulfamethoxazole


Common Uses

Some Potential Side Effects


Trimethoprim/sulfamethoxazole (TMP/SMX)

Bladder infections in women

Treatment and prevention of pneumonia due to Pneumocystis jirovecii Causes (a fungus)

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.