ICD-10 Code A36 – Diphtheria (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code A36 – Diphtheria
What it is
A36 identifies diphtheria, an acute bacterial infection caused by toxin-producing Corynebacterium diphtheriae. It can affect the throat, skin, or other sites and may cause serious systemic illness.
Clinical signs
Clinical features vary; refer to documentation. Typical findings include sore throat, fever, and a gray pseudomembrane in the throat or tonsils, with possible neck swelling and breathing difficulty.
When to use this code
Use A36 when the record documents diphtheria as the confirmed diagnosis, whether respiratory, cutaneous, or another specified form. Apply it only when the provider identifies the infection as diphtheria, not merely suspected exposure or carrier status. Check documentation for site and toxin-related details.
Do not use for
Do not use A36 for simple sore throat, tonsillitis, or other infections without documented diphtheria. Do not assign it for exposure, immunization, or carrier states unless the provider documents active disease.
Coding tip
Look for the organism, anatomic site, and whether the record confirms active diphtheria before coding A36.