If severe enough to require admission and/or recurrent. Single episodes of urticaria that have resolved and there is no obvious trigger are unlikely to benefit from further investigation.
Drug reaction:
Where symptoms are severe (e.g., anaphylaxis, serum sickness, Stevens-Johnson Syndrome) or likely to compromise necessary treatment (e.g., history of penicillin reaction in a patient with enterococcal endocarditis). Patients with reactions during anaesthesia are reviewed by the Anaesthetic Department.
Immunodeficiency:
Patients with a history of severe infections, recurrent infections, and/or infections with unusual organisms.