Allergic Drug Reaction (ADR) and Allergy Testing

Skin testing plays an important role in the diagnosis of allergy. Prick and intradermal test reactions are read and interpreted after 15 min. In the case of rash eruptions, late readings after 24, 48 or 72 hour may be necessary (e.g., when investigating amoxicillin eruptions). Sometimes, skin test reactions can even occur after more than 1 week.

Blood tests to measure specific IgE antibodies to a limited range of drugs (e.g. penicillin, amoxicillin) are available. However, it is not possible to conclusively detect or exclude drug allergy solely on the basis of blood tests.

Blood test results can only be interpreted together with patient history/clinical findings and possibly skin testing.

Provocation tests are necessary when the drug allergy cannot be identified with sufficient reliability on the basis of history, skin testing, and blood test investigations; and when the benefit of result obtained from provocation testing outweighs the risks. In cases of suspected and low likelihood of reactions to drugs that are essential (e. g., pain killers, antibiotics, local anesthetics), provocation tests are necessary and useful. In-patient medical supervision is required when provocation tests have the potential to trigger systemic reactions.