AbstractBackgroundAlthough unexpected and paradoxical, allergic hypersensitivity to corticosteroids is a common finding, delayed‐type reactions being much more frequently encountered than the immediate‐type ones. Although the skin is the main sensitization and elicitation route, other routes, amongst them systemic administration of corticosteroids may exceptionally be involved.ObjectiveTo determine the frequency, clinical presentation and cross‐reactivity patterns for allergic reactions following systemic administration of corticosteroids amongst patients with identified and investigated ‘contact allergy’ to corticosteroids.MethodsWe reviewed clinical data, patch test results and sensitization sources in patients who reacted positively to corticosteroids tested in the K.U. Leuven Dermatology department during an 18‐year period.ResultsSixteen subjects (out of 315 with CS delayed‐type hypersensitivity) presented with allergic manifestations due to systemic administration of corticosteroids. Most patients reacted to molecules from the three groups of the recently reappraised classification.ConclusionThe reactions observed seem to be in most cases ‘systemic contact dermatitis’ due to oral or parenteral re‐exposure of sensitized individuals with the respective corticosteroids previously applied topically. Moreover, most patients seem to be able to react to any corticosteroid molecules and therefore need a systematic individualized evaluation of their sensitization/tolerance profile.