Contact urticaria and related conditions

Contact urticaria (CoU) is an immediate contact reaction occurring within minutes to an hour after exposure to specific proteins or chemicals. CoU is categorised into non-immunologic (NI-CoU) and immunologic (I-CoU) types, with I-CoU potentially leading to anaphylaxis. Both forms of CoU can be associated with protein contact dermatitis and the CoU syndrome. Patients with I-CoU may also have other type I (immediate) allergic diseases, such as allergic conjunctivitis, rhinitis, asthma or food allergy. This review provides a detailed overview of CoU and related conditions, focusing on triggers, diagnostic methods and management strategies. NI-CoU is typically triggered by low molecular weight chemicals, while I-CoU involves IgE-mediated hypersensitivity to both high molecular weight proteins and low molecular weight chemicals. Early diagnosis is crucial, though CoU is often underrecognized. The diagnostic approach includes a thorough medical history, physical examination, evaluation of photographs, (non)invasive skin tests and in vitro assessments. Management strategies prioritise trigger avoidance and pharmacological treatments when avoidance is not fully possible. For I-CoU, second-generation H1-antihistamines are the first-line treatment. Severe cases of I-CoU may benefit from anti-IgE therapy (omalizumab). Patients at risk of anaphylaxis should carry an adrenaline auto-injector and wear a medical alert bracelet.