Contact Urticaria and Related Conditions: Clinical Review.

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.