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Definition of Sulfonamides

  • Medical Author:
    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

Sulfonamides: The sulfa-related group of antibiotics, which are used to treat bacterial infection and some fungal infections.

Examples of sulfonamides includes sulfadiazine, sulfamethizole (brand name: Thiosulfil Forte), sulfamethoxazole (Gantanol), sulfasalazine (Azulfidine), sulfisoxazole (Gantrisin), and various high-strength combinations of three sulfonamides.

Sulfa drugs kill bacteria and fungi by interfering with cell metabolism. They were the wonder drugs before penicillin and are still used today. Because sulfa drugs concentrate in the urine before being excreted, treating urinary tract infections is one of their most common uses.

Sulfa drugs can have a number of potentially dangerous interactions with prescription and over-the-counter drugs (including PABA sunscreens), and are not appropriate for patients with some health conditions. Many people are allergic to sulfa medications. Be sure your doctor knows about any other medications you take, your medication allergies and your full health history before taking sulfonamides.

Reviewed on 12/27/2018

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