Table 1. Antibiotic allergy classifications.

Type	Mechanism	Clinical examples	Common antibiotic examples	Antibiotic recommendation
Type A adverse drug reactions – non-immune-mediated
Non-severe	Pharmacologically predictable reactions	Nausea, vomiting, diarrhoea, pruritis (without rash), headache	Beta-lactams	Use all antibiotics
Severe		Encephalitis, renal impairment, tendinopathy	Cefepime, aminoglycosides, fluoroquinolones	Only avoid the implicated drug or dose
Type B adverse drug reactions – immune-mediated
1	IgE-mediated	Urticaria, angioedema, bronchospasm, anaphylaxis	Penicillins, cephalosporins	Avoid implicated drug. Caution with drugs in the same class and structurally related drugs
2	Antibody (usually IgG)-mediated cell destruction	Haemolytic anaemia, thrombocytopenia, vasculitis	Penicillins, cephalosporins
3	IgG or IgM and complement	Fever, rash, arthralgia	Penicillin, amoxicillin, cefaclor
4	T-cell mediated	Maculopapular exanthema, drug reaction with eosinophilia and systemic symptoms (DRESS), Stevens-Johnson syndrome, toxic epidermal necrolysis, acute generalised exanthematous pustulosis	Beta-lactams, glycopeptides, sulfonamides	Avoid implicated drug, drugs in the same class and structurally related drugs
Anaphylactoid reactions – non-immune-mediated
Non-IgE-mediated	Direct mast-cell stimulation or basophil activation	Flushing, itching, urticaria, angioedema	Vancomycin, macrolides, fluoroquinolones	Manage the reaction, either by slowing the infusion or premedication (with antihistamines or corticosteroids)