2026 ICD-10-CM Diagnosis Code J16.0Chlamydial pneumonia

ICD-10-CM Codes›J00–J99›J09-J18›J16

ICD-10-CM J16.0
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

J16.0 is a billable ICD-10-CM diagnosis code for chlamydial pneumonia. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 193 through 195. Coders also document this condition as Chlamydia pneumoniae infection. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Bacterial infections and Pneumonia (except that caused by tuberculosis).

Code Identity

ICD-10-CM Code
J16.0
Billable Status
Yes — Valid for Submission
Code Describes
Chlamydial pneumonia
Short Description
Chlamydial pneumonia
Same as the full description in the CMS dataset.
Parent Code
J16
Pneumonia due to other infectious organisms, not elsewhere classified

Code Classification

ChapterJ00–J99Diseases of the respiratory system
SectionJ09-J18Influenza and pneumonia
CategoryJ16Pneumonia due to other infectious organisms, not elsewhere classified
This CodeJ16.0Chlamydial pneumonia

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Chlamydia pneumoniae infection
  • Pneumonia caused by Chlamydia pneumoniae
  • Pneumonia caused by Chlamydiaceae

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Pneumonia(acute) (double) (migratory) (purulent) (septic) (unresolved)
      • chlamydial
    • Pneumonia(acute) (double) (migratory) (purulent) (septic) (unresolved)
      • in (due to)
        • Chlamydia

Clinical ClassificationClinical

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

CCSR INF003
Bacterial infections
Default principal diagnosis: inpatient No · outpatient No
CCSR RSP002
Pneumonia (except that caused by tuberculosis)
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Chlamydial Pneumonia

    pneumonia caused by infections with the genus chlamydia; and chlamydophila, usually with chlamydophila pneumoniae.

Patient EducationClinical

Pneumonia

Pneumonia is an infection in one or both of your lungs. It causes the air sacs of your lungs to fill up with fluid or pus. Pneumonia can range from mild to severe, depending on what caused it, your age, and your overall health.

The full article covers:

  • What is pneumonia?
  • What causes pneumonia?
  • Who is more likely to develop pneumonia?
  • What are the symptoms of pneumonia?
  • What other problems can pneumonia cause?
  • How is pneumonia diagnosed?
  • What are the treatments for pneumonia?
  • Can pneumonia be prevented?

Read the full article at MedlinePlus

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

Convert J16.0 to ICD-9-CMHistory

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

ICD-9-CM
483.1 Pneumonia d/t chlamydia
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 J16.0Overview

Is J16.0 a billable code?

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

What MS-DRG does J16.0 group to?

When chlamydial pneumonia is the principal diagnosis on an inpatient stay, it groups to MS-DRG 193, 194, 195, with relative weights from 0.6285 to 1.3144 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of J16.0?

Under the General Equivalence Mappings, chlamydial pneumonia converts to ICD-9-CM 483.1 (pneumonia d/t chlamydia). The mapping is a direct match.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.