2026 ICD-10-CM Diagnosis Code A36.1Nasopharyngeal diphtheria

ICD-10-CM Codes›A00–B99›A30-A49›A36

ICD-10-CM A36.1
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

A36.1 is a billable ICD-10-CM diagnosis code for nasopharyngeal diphtheria. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 11 through 13, 154 through 156. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 12 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Bacterial infections and Other specified upper respiratory infections.

Code Identity

ICD-10-CM Code
A36.1
Billable Status
Yes — Valid for Submission
Code Describes
Nasopharyngeal diphtheria
Short Description
Nasopharyngeal diphtheria
Same as the full description in the CMS dataset.
Parent Code
A36
Diphtheria

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionA30-A49Other bacterial diseases
CategoryA36Diphtheria
This CodeA36.1Nasopharyngeal diphtheria

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Nasopharyngeal diphtheria
  • Pharyngeal diphtheria
  • Respiratory diphtheria

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR INF003
Bacterial infections
Default principal diagnosis: inpatient No · outpatient No
CCSR RSP006
Other specified upper respiratory infections
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Nasopharyngeal Diphtheria

    infection of the nasopharynx by corynebacterium diphtheriae.

Patient EducationClinical

Diphtheria

Diphtheria is a serious bacterial infection. You can catch it from a person who has the infection and coughs or sneezes. You can also get infected by coming in contact with an object, such as a toy, that has bacteria on it.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert A36.1 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
032.1 Nasopharynx diphtheria
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About A36.1Overview

What is the ICD-10 code for nasopharyngeal diphtheria?

The ICD-10-CM code for nasopharyngeal diphtheria is A36.1 (sometimes written as A361). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Is A36.1 (Diphtheria) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report nasopharyngeal diphtheria on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does A36.1 group to?

When nasopharyngeal diphtheria is the principal diagnosis on an inpatient stay, it groups to MS-DRG 11, 12, 13, 154, 155, 156, with relative weights from 0.6911 to 5.4541 depending on complications. Higher weights mean higher Medicare reimbursement.

Is A36.1 a CC or MCC?

CMS lists A36.1 as a CC (complication or comorbidity) for FY 2026. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 12 closely related codes in its exclusion list.

What is the ICD-9 equivalent of A36.1?

Under the General Equivalence Mappings, nasopharyngeal diphtheria converts to ICD-9-CM 032.1 (nasopharynx diphtheria). The mapping is a direct match.