Urticaria due to cold and heat

This diagnosis code represents a form of physical urticaria where hives, angioedema, or both, are triggered by exposure to either cold or heat stimuli. This reaction is non-allergic and typically presents as transient, itchy wheals on the skin. It encompasses both cold-induced and heat-induced urticaria that are not hereditary.

Assign this code when documentation specifies urticaria caused by exposure to cold temperatures (e.g., cold air, water, or objects) or heat (e.g., hot water, exercise, or sun exposure). Look for physician notes indicating "cold urticaria," "heat urticaria," or "physical urticaria due to temperature changes." This code is appropriate for acquired forms of these conditions.

• Differentiate from familial cold urticaria (M04.2), which is a distinct genetic condition and is excluded from this code.
• Ensure the documentation clearly links the urticaria to either cold or heat exposure, not other physical triggers like pressure or vibration.
• Consider sequencing this code as a primary diagnosis if it is the reason for the encounter, or as a secondary diagnosis if it's a co-morbidity.