ICD-10 Code L50.1 – Idiopathic Urticaria (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code L50.1 – Idiopathic urticaria
What it is
L50.1 identifies urticaria, or hives, when no specific cause is documented. Use it for spontaneous wheals and itching that are not explained by an allergen, infection, medication, or another known trigger.
Clinical signs
Clinical features vary; refer to documentation. Typical findings include transient raised wheals, pruritus, and occasional swelling. The record should show that the condition is idiopathic or that no cause has been established.
When to use this code
Use L50.1 when the provider documents idiopathic urticaria, chronic hives of unknown origin, or urticaria without an identified trigger. It is also appropriate when workup is incomplete and the note clearly states the cause is unknown. If a specific trigger is documented, code that condition instead.
Do not use for
Do not use this code for allergic urticaria, contact urticaria, or other urticaria with a documented cause. Check documentation if the rash is described as a different skin disorder.
Coding tip
Code L50.1 only when the chart supports “idiopathic” or “unknown cause”; otherwise, select the more specific urticaria code.