Other antimicrobial allergies


Patients who have an allergic reaction to a sulfonamide antibiotic should not be labelled as ‘allergic to sulfur’. 

There is no cross-reactivity between sulfonamide antibiotics and non-antibiotic sulfonamides (e.g. sulfonylurea anti-diabetic drugs or diuretics such as frusemide). The only exception is sulfasalazine (Salazopyrin, Pyralin) – avoid sulfonamide antibiotics in patients with a history of hypersensitivity to sulfasalazine, and vice versa.

Cross-reactivity between antibiotic sulfonamides is estimated to be approximately 10%.

Sulfonamide antibiotics

Generic name - Common brands

  • Sulfamethoxazole - Resprim, Septrim, Septrim Forte, Bactrim DS (in combination with trimethoprim)
  • Sulfadiazine - Flamazine (silver sulfadiazine cream) - No oral or IV formulations marketed in Australia
  • Sulfacetamide - Bleph-10 eye drops

More information on sulfonamide allergies is available from Australian Society of Clinical Immunology and Allergy (ASCIA) website


Carbapenems available in Australia include:

  • meropenem
  • ertapenem
  • doripenem
  • imipenem.

The beta-lactam core structure of carbapenems is significantly different to penicillins and the risk of cross-reactive allergy to carbapenems in those who are allergic to penicillins is negligible.

Due to their broad spectrum, carbapenems are usually administered in the hospital setting where a drug challenge can be considered if required.