Physical urticarias: diagnosis and testing

Physical urticaria is a subtype of chronic inducible urticaria in which a physical stimulus induces urticaria and/or angioedema. The most common physical urticaria subtype is symptomatic dermographism, where wheals develop within minutes of a skin friction stimulus. Testing for dermographism can be performed with instruments commonly found in a physician office, such as a tongue blade. The second most common type of physical urticaria is cold-contact urticaria for which there are three subtypes: primary acquired, secondary acquired, and hereditary. Hereditary forms should be considered when patients have characteristic symptoms but negative ice cube provocation testing. Testing modalities also exist for delayed pressure, heat contact, vibratory, and solar urticaria, less common but still significant forms of physical urticaria.