Diagnosis of penicillin allergy

A history of penicillin allergy is relatively common in hospital patients, and is in most not due to type I hypersensitivity reactions.

A diagnosis of penicillin allergy crucially requires a detailed history of the drug reaction, and can be confirmed by a positive skin prick test to the major and minor determinants of penicillin. Skin prick testing is carried out if there is a clinical need for penicillin treatment e.g. treatment of infective endocarditis. A patient is unlikely to develop anaphylaxis with a negative penicillin skin prick test. The detection of penicillin specific IgE in the serum is unreliable.

Further Reading

• Diagnosis and management of penicillin allergy.