Urticaria (Hives) ICD-10-CM codes

L50.9 (urticaria, unspecified) is the default when hives are documented without a cause. When the trigger is stated, use the specific 4th character: L50.0 allergic urticaria, L50.1 idiopathic urticaria (the usual code for chronic spontaneous urticaria), L50.2 cold or heat urticaria, L50.3 dermatographic urticaria, L50.5 cholinergic urticaria, and L50.6 contact urticaria. Solar urticaria is classified with the radiation-related skin disorders as L56.3.

Angioedema is coded separately as T78.3XXA when it occurs with or without hives; report both L50.- and T78.3XXA if both are documented. Urticaria from a correctly taken drug is L50.0 plus a T36-T50 adverse effect code (5th or 6th character 5) for the drug. Anaphylaxis takes precedence: assign T78.2XXA or the specific T78.0- food anaphylaxis code, with urticaria as a secondary code only if the provider lists it separately.

Chronic versus acute duration does not change the L50 code. Allergic contact dermatitis (L23.-) and dermatitis due to substances taken internally (L27.-) are excluded from L50 and should be used when the eruption is eczematous rather than wheals.