Sulfonamides - Benefits, dosage and side effects

Sulfonamides or sulfas are class of antibiotics used to treat bacterial infections. Sulfa can be used for mentreat various diseases caused by bacterial infections, such as urinary tract infections, bronchitis, bacterial meningitis, pneumonia, and eye or ear infections.

Sulfonamides work by interfering with the formation of folic acid in bacteria. Folic acid is a nutrient needed by bacteria to form nucleic acids, DNA, and RNA, so that bacteria can reproduce. If the process of formation of folic acid is disturbed, bacteria cannot reproduce.

Precautions Before Using Sulfonamides

  • Do not use sulfonamides if you have an allergy to this medicine or to any medicine with a sulfa combination in it.
  • Do not use sulfonamides if you are pregnant or breastfeeding.
  • Sulfonamides should not be used in children under 2 months of age.
  • Talk to your doctor about taking sulfonamides if you are 65 years of age or older.
  • Immediately stop using sulfonamides if a rash appears on the skin. Continued use can make the rash worse.
  • Sulfonamides can make the skin more sensitive to sunlight. Therefore, avoid exposure to direct sunlight or use sunscreen when out of the house, while using this medicine.
  • Tell your doctor if you have a history of asthma, blood diseases (such as agranulocytosis and aplastic anemia), G6PD deficiency, kidney disease, and liver disease.
  • Tell your doctor if you are taking warfarin, cyclosporine, digoxin, methotrexate, valproic acid, pyrimethamine, clozapine, and leucovorin.
  • Call your doctor right away if you experience an allergic reaction or overdose after taking this medicine.

Side Effects and Dangers of Sulfonamides

Side effects that may arise due to the use of sulfonamides can be different for each person. Some of the possible side effects are:

  • Nauseous
  • Throw up
  • Dizzy
  • Headache
  • Diarrhea
  • Rash

Although rare, sulfonamides can also cause serious side effects, including leukopenia, anemia, leukemia, bladder stones, and damage to the liver. Always follow the recommendations and dosages given by the doctor, and do regular check-ups as recommended by the doctor when using this medicine.

Types and Trademarks of Sulfonamides

The following are the types and trademarks of sulfonamides:


Sulfamethoxazole is generally combined with trimethoprim. This combination drug is called cotrimoxazole.

Sulfamethoxazole-trimethoprim trademarks: Bactoprim, Bactrim, Cotrimoxazole, Fasiprim, Novatrim, Pehatrim, Primadex, Primazole, Primavon, Sanprima

To find out the dosage and more information about this drug, please visit the sulfamethoxazole drug page.


Trademarks of sulfisoxazole:-

Drug form: drink

  • Adult dose: 4–8 grams per day, divided into 4–6 doses.
  • Dosage for children >2 months: 75 mg/kg per day, divided into 4–6 doses. Maximum dose: 150 mg/kg body weight per day or equal to 6 grams per day.