Allergy testing to confirm trimethoprim+sulfamethoxazole hypersensitivity in adults

Many patients who report a ‘sulfur’ allergy do not have a reproducible immune-mediated allergy (immediate or delayed hypersensitivity) on testing.

Recent international and local data have demonstrated that in patients with low-risk trimethoprim+sulfamethoxazole allergy, direct oral challenge (ie oral challenge without prior skin testing) can be performed to enable the use of trimethoprim+sulfamethoxazole – this is particularly useful for patients with immune compromiseRose, 2021Krantz, 2020.

For allergy testing in patients with severe (immediate or delayed) or nonsevere delayed hypersensitivity, seek expert advice.