2026 ICD-10-CM Diagnosis Code S03.42XASprain of jaw, left side, initial encounter

ICD-10-CM Codes›S00–T88›S00-S09›S03

ICD-10-CM S03.42XA
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

S03.42XA is a billable ICD-10-CM diagnosis code for sprain of jaw, left side, initial encounter. The 7th character A marks it as an initial encounter code, used while the patient is receiving active treatment. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 157 through 159, 963 through 965. Coders also document this condition as left jaw sprain. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Any dental condition including traumatic injury; and Sprains and strains, initial encounter.

Code Identity

ICD-10-CM Code
S03.42XA
Billable Status
Yes — Valid for Submission
Code Describes
Sprain of jaw, left side, initial encounter
Short Description
Sprain of jaw, left side, initial encounter
Same as the full description in the CMS dataset.
Parent Code
S03.42
Sprain of jaw, left side

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionS00-S09Injuries to the head
CategoryS03Dislocation and sprain of joints and ligaments of head
This CodeS03.42XASprain of jaw, left side, initial encounter

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Left jaw sprain
  • Sprain of jaw

Coding GuidelinesGuidance

The appropriate 7th character is to be added to each code from block Dislocation and sprain of joints and ligaments of head (S03). Use the following options for the applicable episode of care:

  • A - initial encounter
  • D - subsequent encounter
  • S - sequela

Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026, published by CMS and the National Center for Health Statistics.

Clinical ClassificationClinical

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

CCSR DEN001
Any dental condition including traumatic injury
Default principal diagnosis: inpatient No · outpatient No
CCSR INJ024
Sprains and strains, initial encounter
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Jaw Injuries and Disorders

Your jaw is a set of bones that holds your teeth. It includes:

Read the full article at MedlinePlus

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

Convert S03.42XA to ICD-9-CMHistory

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

ICD-9-CM
848.1 Sprain of jaw
Approximate The match is approximate rather than exact.

Code History & ChangesHistory

Replacement S03.42XA replaces the following previously assigned code(s):

  • S03.4XXA - Sprain of jaw, initial encounter
FY 2018AddedAdded to the ICD-10-CM code setEffective October 1, 2017.
FY 2019–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About S03.42XAOverview

Is S03.42XA (Sprain of jaw, left side) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report sprain of jaw, left side, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character A in S03.42XA mean?

The final character A marks the initial encounter: use it while the patient is receiving active treatment for sprain of jaw, left side, such as an emergency visit or first evaluation.

What MS-DRG does S03.42XA group to?

When sprain of jaw, left side, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 157, 158, 159, 963, 964, 965, with relative weights from 0.7085 to 2.7338 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of S03.42XA?

Under the General Equivalence Mappings, sprain of jaw, left side, initial encounter converts to ICD-9-CM 848.1 (sprain of jaw). The mapping is approximate, so confirm the match fits the documentation.

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.