When scarlet fever is confirmed by a positive rapid antigen detection test (RADT), nucleic acid amplification test (NAAT), or throat culture, antibiotic treatment is required regardless of patient age. In patients with a penicillin allergy, the standard first-choice regimen cannot be used and an alternative must be selected carefully.
A patient with scarlet fever has a confirmed positive streptococcal test — by rapid antigen detection, NAAT, or throat culture — and a documented penicillin allergy. The allergy status changes which antibiotic regimens are appropriate, and the specific nature of the allergy (including whether immediate-type hypersensitivity is present) further narrows the options.
Multiple alternative antibiotic regimens are recommended — the appropriate choice depends on the type of penicillin allergy present, as certain options must be avoided in patients with immediate-type hypersensitivity reactions.
The complete regimen options, selection criteria, and full clinical decision pathway are in the protocol below.