ICD-10 Code A36.1 – Nasopharyngeal diphtheria (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code A36.1 – Nasopharyngeal diphtheria
What it is
A36.1 identifies diphtheria infection involving the nasopharynx, the upper airway behind the nose. Use it when documentation specifies nasopharyngeal diphtheria rather than another diphtheria site.
Clinical signs
Clinical features may include sore throat, nasal discharge, and a grayish membrane in the upper airway. Check documentation for respiratory obstruction, cervical swelling, or other site-specific findings.
When to use this code
Use A36.1 when the provider documents nasopharyngeal diphtheria, including confirmed or clinically diagnosed cases tied to that location. It is appropriate when the record clearly distinguishes the nasopharynx from laryngeal, pharyngeal, or cutaneous diphtheria. If the site is unclear, check documentation.
Do not use for
Do not use this code for diphtheria at another anatomic site or for suspected exposure without diagnosed infection. If the chart only says “diphtheria” without location, check documentation before assigning A36.1.
Coding tip
Code the documented site exactly; nasopharyngeal involvement must be stated or clearly supported in the record.