How Do Sulfonamides Work?

Sulfonamides or sulfa drugs are a class of antibiotics that target bacteria causing infections. These classes of drugs are generally broad-spectrum antibiotics that act on a wide range of bacterial types and are therefore employed in treating many kinds of bacterial infections. Sulphonamides do not kill bacteria, but it interferes with the ability of bacteria to grow and multiply (bacteriostatic).

Folic acid is a key component of bacteria that it uses for growth and multiplication. Sulfa drugs block the ability of the bacteria to use folic acid, thereby inhibiting the growth process. As a result, the bacteria fail to reproduce and spread. Because humans do not make folic acid and completely rely on diet for getting their folic acid, they remain safe against the adverse effects of inhibition of folate production.

Sometimes, sulfa drugs are given in combination with trimethoprim because it kills the bacteria (bactericidal). Hence, the combination of sulfonamides and trimethoprim stops the bacteria from multiplying and kills them as well.

Sulfonamides are mainly used to treat bacterial infections and some fungal infections. As they tend to concentrate more in the urine, they are most effective against urinary tract infections.

Some of the side effects of sulfonamides include:

• Lethargy
• Diarrhea
• Anorexia
• Nausea
• Vomiting
• Dizziness
• Headache
• Photosensitivity (sunburn after exposure to sunlight)
• Serious skin rashes
  • Serious skin rashes include:
    • Steven-Johnson Syndrome, which causes aching joints and muscles, redness, blistering, and skin peeling.
    • Toxic epidermal necrolysis causes difficulty in swallowing; peeling, redness, loosening, and blistering of the skin.

Rare side effects include:

• Hepatotoxicity (liver damage)
• Low white blood cell count
• Thrombocytopenia (low platelet count)
• Anemia

The information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

Names of Sulfonamides include:

• Bactrim
• Bactrim DS
• Cotrim
• Cotrimoxazole
• Erythromycin/sulfisoxazole
• Pediazole
• Septra
• Septra DS
• Sulfadiazine
• Sulfatrim
• Trimethoprim/sulfamethoxazole