2026 ICD-10-CM Diagnosis Code J45.31Mild persistent asthma with (acute) exacerbation

ICD-10-CM Codes›J00–J99›J40-J4A›J45

ICD-10-CM J45.31
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

J45.31 is a billable ICD-10-CM diagnosis code for mild persistent asthma with (acute) exacerbation. 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 29 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Asthma.

J45.31 does not risk-adjust for Medicare Advantage under the CMS-HCC V28 model. It still risk-adjusts in the RxHCC Part D (V08) category 229 for payment year 2026.

This medical diagnosis code is frequently used in Pediatrics medical specialties to designate conditions such asthma.

Code Identity

ICD-10-CM Code
J45.31
Billable Status
Yes — Valid for Submission
Code Describes
Mild persistent asthma with (acute) exacerbation
Short Description
Mild persistent asthma with (acute) exacerbation
Same as the full description in the CMS dataset.
Parent Code
J45.3
Mild persistent asthma

Code Classification

ChapterJ00–J99Diseases of the respiratory system
SectionJ40-J4AChronic lower respiratory diseases
CategoryJ45Asthma
This CodeJ45.31Mild persistent asthma with (acute) exacerbation

Medicare Risk Adjustment (HCC)Billing

J45.31 does not risk-adjust for Medicare Advantage under the CMS-HCC V28 model, but it maps to payment categories in the other CMS models shown below.

CMS-HCC V28 (Medicare Advantage Payment Model)
Not mapped
no payment category in the model that pays 100% of MA risk scores
Prior Model (CMS-HCC V24)
Not mapped under V24
this diagnosis newly risk-adjusts under the V28 model
Part D (RxHCC)
RxHCC 229 — Chronic Obstructive Pulmonary Disease, Bronchiectasis, and Other Asthma
also risk-adjusts in the Part D prescription drug model (V08)

Source: CMS Payment Year 2026 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute exacerbation of allergic asthma
  • Acute exacerbation of asthma co-occurrent with allergic rhinitis
  • Acute severe exacerbation of allergic asthma
  • Acute severe exacerbation of asthma co-occurrent with allergic rhinitis
  • Acute severe exacerbation of immunoglobin E-mediated allergic asthma
  • Acute severe exacerbation of mild persistent allergic asthma
  • Acute severe exacerbation of mild persistent allergic asthma co-occurrent with allergic rhinitis
  • Acute severe exacerbation of mild persistent asthma
  • Exacerbation of mild persistent asthma
  • Mild asthma
  • Mild persistent allergic asthma
  • Mild persistent allergic asthma uncontrolled
  • Mild persistent asthma
  • Mild persistent asthma co-occurrent with allergic rhinitis
  • Mild persistent asthma uncontrolled

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 RSP009
Asthma
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Asthma

Asthma is a chronic (long-term) lung disease. It affects your airways, the tubes that carry air in and out of your lungs. When you have asthma, your airways can become inflamed and narrowed. This can cause wheezing, coughing, and tightness in your chest. When these symptoms get worse than usual, it is called an asthma attack or flare-up.

The full article covers:

  • What is asthma?
  • What causes asthma?
  • Who is at risk for asthma?
  • What are the symptoms of asthma?
  • How is asthma diagnosed?
  • What are the treatments for asthma?

Read the full article at MedlinePlus

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

Convert J45.31 to ICD-9-CMHistory

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

ICD-9-CM
493.02 Ext asthma w(acute) exac
Approximate The match is approximate rather than exact.
ICD-9-CM
493.12 Int asthma w (ac) exac
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 J45.31Overview

What is the ICD-10 code for mild persistent asthma with (acute) exacerbation?

The ICD-10-CM code for mild persistent asthma with (acute) exacerbation is J45.31 (sometimes written as J4531). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Is J45.31 (Mild persistent asthma) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report mild persistent asthma with (acute) exacerbation on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does J45.31 group to?

When mild persistent asthma with (acute) exacerbation 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 J45.31 a CC or MCC?

CMS lists J45.31 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 29 closely related codes in its exclusion list.

What is the ICD-9 equivalent of J45.31?

Under the General Equivalence Mappings, mild persistent asthma with (acute) exacerbation converts to ICD-9-CM 493.02 (ext asthma w(acute) exac) and 493.12 (int asthma w (ac) exac). The mapping is approximate, so confirm the match fits the documentation.

Does J45.31 risk-adjust for Medicare Advantage payment?

Not for Medicare Advantage: J45.31 maps to no category in the CMS-HCC V28 model. It still risk-adjusts in the RxHCC Part D (V08) category 229 (Chronic Obstructive Pulmonary Disease, Bronchiectasis, and Other Asthma).