2026 ICD-10-CM Diagnosis Code M79.12Myalgia of auxiliary muscles, head and neck

ICD-10-CM Codes›M00–M99›M70-M79›M79

ICD-10-CM M79.12
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M79.12 is a billable ICD-10-CM diagnosis code for myalgia of auxiliary muscles, head and neck. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 555 through 556. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Musculoskeletal pain, not low back pain.

Code Identity

ICD-10-CM Code
M79.12
Billable Status
Yes — Valid for Submission
Code Describes
Myalgia of auxiliary muscles, head and neck
Short Description
Myalgia of auxiliary muscles, head and neck
Same as the full description in the CMS dataset.
Parent Code
M79.1
Myalgia

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM70-M79Other soft tissue disorders
CategoryM79Other and unspecified soft tissue disorders, not elsewhere classified
This CodeM79.12Myalgia of auxiliary muscles, head and neck

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.

    • Myalgia
      • auxiliary muscles, head and neck

Clinical ClassificationClinical

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

CCSR MUS010
Musculoskeletal pain, not low back pain
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Myalgia

    painful sensation in the muscles.

  • Myotoxicity

    damage to the muscle or its function secondary to toxic substances such as drugs used in chemotherapy; immunotherapy; or radiation.

  • Pleurodynia, Epidemic

    an acute, febrile, infectious disease generally occurring in epidemics. it is usually caused by coxsackieviruses b and sometimes by coxsackieviruses a; echoviruses; or other enteroviruses.

Patient EducationClinical

Muscle Disorders

Your muscles help you move and help your body work. Different types of muscles have different jobs. There are many problems that can affect muscles. Muscle disorders can cause weakness, pain or even paralysis.

Read the full article at MedlinePlus

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

Code History & ChangesHistory

Replacement M79.12 replaces the following previously assigned code(s):

  • M79.1 - Myalgia
FY 2019AddedAdded to the ICD-10-CM code setEffective October 1, 2018.
FY 2020–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About M79.12Overview

Is M79.12 (Myalgia) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report myalgia of auxiliary muscles, head and neck on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M79.12 group to?

When myalgia of auxiliary muscles, head and neck is the principal diagnosis on an inpatient stay, it groups to MS-DRG 555, 556, with relative weights from 0.8306 to 1.3218 depending on complications. Higher weights mean higher Medicare reimbursement.

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.