Algorithm to identify patients at low risk for penicillin allergy

What was the timing of this reaction?

Acute

Symptoms occurred < 2 hours after the last dose of antibiotics AND on the first day of therapy with this course of antibiotics

Delayed

Symptoms occurred >2 hours after the last dose of antibiotics AND after the first day of therapy

Unclear

The timing is not clear (inadequate details from history), or timing does not fit into above.