Sulfonamides

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

Sulfonamides are a class of antibiotics that are effective against many gram-positive bacteria and gram-negative bacteria. Some sulfonamides are applied directly to the skin (topically) to treat burns and skin, vaginal, and eye infections.

Sulfonamides include the following:

  • Sulfadoxine

  • Sulfamethizole

  • Sulfisoxazole

Sulfamethoxazole (SMX) is commonly used in combination with (TMP). The combination is called TMP/SMX.

Table

(See also Overview of Antibiotics.)

Use of Sulfonamides During Pregnancy and Breastfeeding

Sulfonamides should be used during pregnancy only when the benefits of treatment outweigh the risks. However, they should not be used when the due date is near because, if taken at that time, they may cause jaundice that may be severe enough to cause brain damage (kernicterus) in the fetus or in the newborn. (See also Safety of Medications During Pregnancy.)

Sulfonamides should not be taken during breastfeeding. (See also Medication and Substance Use During Breastfeeding.)

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