Coombs and Gell Classification

Coombs and Gell Classification

Mediator: IgE antibodies

Onset: Less than 1hr (Rarely up to 72 hours)

Clinical Reaction: Anaphylaxis, urticaria, angioedema, hypotension, bronchospasm, stridor, pruritis


  • Penicillins: 0.015 – 0.2%

  • Cephalosporins: 0.0001 – 0.1%

Avoid the offending agent and side chain related agents

Mediator: IgG and IgM antibodies

Onset: Greater than 72 hours

Clinical Reaction: Hemolytic anemia, thrombocytopenia, neutropenia

Comments: Drug specific, avoid the offending agent

Mediator: IgG and IgM complexes

Onset: Greater than 72 hours

Clinical Reaction: Serum sickness, glomerulonephritis, small vessel vasculitis, drug fever

Comments: Antibody-antigen complexes precipitate in tissues and potentially affect any end organ

Mediator: T-Cells

Onset: Greater than 72 hours

Clinical Reaction: Contact dermatitis, pustulosis

Comments: Incidence is low

  • Ex: Eosinophilia, bullous exanthems, severe exfoliative dermatoses (ex. SJS/TEN), interstitial nephritis, immune hepatitis and some morbilliform or maculopapular rashes

Mediator: Unknown

Onset: Usually greater than 72 hours

Clinical Reaction: Maculopapular or morbilliform rashes

Comments: 1 – 4% of patients receiving beta-lactams. Not a contraindication to future use of beta-lactam antibiotics

More Information

Defined as serious hypersensitivity reaction that is rapid in onset and may cause death, typically involving the skin, mucosal tissue or both and either respiratory compromise (e.g. dyspnea, wheeze-bronchospasm, stridor, reduced peak expiratory flow, hypoxemia) or reduced blood pressure or the associated symptoms and signs of end-organ dysfunction