Classification Scheme for Adverse Drug Reactions Described by Gell and Coombs31

ClassificationTime of Onset, hMediator(s)Clinical SignsSkin Testing UsefulComments
Allergic immediate (type I)<1Antibiotic-specific IgE antibodiesAnaphylaxis and/or hypotension, laryngeal edema, wheezing, angioedema, or urticariaYesMuch more likely with parenteral than oral administration; fatal outcome in 1 per 50 000 to 1 per 100 000 treatment courses with penicillin; accelerated reactions occurring 1–72 h after exposure may be IgE mediated
Late (type II)>72IgG, complementIncreased clearance of red blood cells and platelets by lymphoreticular systemNoIgE not involved
Type III>72IgG and IgM immune complexesSerum sickness, tissue injuryNoTissue lodging of immune complexes; drug fever; IgE not involved
Type IV≥72Contact dermatitisNoIgE not involved
Other (idiopathic)Usually >72Maculopapular or morbilliform rashesNo1–4% of all patients receiving penicillins and cephalosporins