2026 ICD-10-CM Diagnosis Code A37.90Whooping cough, unspecified species without pneumonia

ICD-10-CM Codes›A00–B99›A30-A49›A37

ICD-10-CM A37.90
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

A37.90 is a billable ICD-10-CM diagnosis code for whooping cough, unspecified species without pneumonia. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 202 through 203. 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 8 closely related codes. Coders also document this condition as acute bacterial bronchitis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Bacterial infections.

Code Identity

ICD-10-CM Code
A37.90
Billable Status
Yes — Valid for Submission
Code Describes
Whooping cough, unspecified species without pneumonia
Short Description
Whooping cough, unspecified species without pneumonia
Same as the full description in the CMS dataset.
Parent Code
A37.9
Whooping cough, unspecified species

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionA30-A49Other bacterial diseases
CategoryA37Whooping cough
This CodeA37.90Whooping cough, unspecified species without pneumonia

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute bacterial bronchitis
  • Infection caused by Bordetella
  • Meningitis caused by Bordetella pertussis
  • Pertussis
  • Whooping cough-like syndrome

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 Yes · outpatient Yes

Patient EducationClinical

Whooping Cough

Whooping cough, or pertussis, is a respiratory infection that can cause coughing fits. In serious cases, the coughing can become violent and rapid. You may cough so hard that you vomit. The name of the disease comes from the whooping noise you might make when you try to breathe in after coughing.

The full article covers:

  • What is whooping cough?
  • What causes whooping cough?
  • What are the symptoms of whooping cough?
  • How is whooping cough diagnosed?
  • What are the treatments for whooping cough?
  • Can whooping cough be prevented?

Read the full article at MedlinePlus

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

Convert A37.90 to ICD-9-CMHistory

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

ICD-9-CM
033.9 Whooping cough NOS
Approximate The match is approximate rather than exact.

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 A37.90Overview

What is the ICD-10 code for whooping cough, unspecified species without pneumonia?

The ICD-10-CM code for whooping cough, unspecified species without pneumonia is A37.90 (sometimes written as A3790). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Is A37.90 (Whooping cough, unspecified species) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report whooping cough, unspecified species without pneumonia on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does A37.90 group to?

When whooping cough, unspecified species without pneumonia is the principal diagnosis on an inpatient stay, it groups to MS-DRG 202, 203, with relative weights from 0.6700 to 0.9712 depending on complications. Higher weights mean higher Medicare reimbursement.

Is A37.90 a CC or MCC?

CMS lists A37.90 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 8 closely related codes in its exclusion list.

What is the ICD-9 equivalent of A37.90?

Under the General Equivalence Mappings, whooping cough, unspecified species without pneumonia converts to ICD-9-CM 033.9 (whooping cough NOS). The mapping is approximate, so confirm the match fits the documentation.