Cutaneous allergy encompasses a broad spectrum of clinical presentations with complex underlying immunological mechanisms. Allergy may be considered to play a role in disorders that include atopic dermatitis, contact dermatitis, urticaria, angioedema, anaphylaxis and adverse drug reactions. The skin phenotypes associated with allergy are more commonly exhibited in non-allergic disease and so a high proportion of patients who consider themselves allergic in truth have other, nonallergic explanations for their presentation. Investigations may help to delineate those individuals who are more likely to have true allergy, but tests currently available have significant limitations and are open to easy misinterpretation. As a consequence, any investigations are best carried out by someone experienced in managing patients with potentially allergic disorders.