M79.7: Fibromyalgia

The ICD-10-CM code for fibromyalgia, fibrositis, fibromyositis or myofibrositis when the provider diagnoses the condition, rather than recording muscle pain, myalgia or myofascial pain alone.

Billable

FY2027

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At a glance

Code Family

M79: Other and unspecified soft tissue disorders, not elsewhere classified.

DRG Grouping

MS-DRG 555 or 556, Signs and symptoms of musculoskeletal system and connective tissue, when M79.7 is the principal diagnosis under the FY2027 MS-DRG v44 grouper.

HCC Mapping (v28)

None. M79.7 does not map to a payment HCC in the CMS-HCC v28 crosswalk.

Family Specificity

Fifty-two billable codes sit in M79, counting M79.7. M79.7 is a complete code with no site, laterality or severity axis.

Billable

Yes. M79.7 is a complete code in the FY2027 billable code list.

Effective Date

Valid in the FY2026 code set and unchanged in the FY2027 update.

Which M79 code do I assign?

Category M79 splits other soft tissue disorders by the condition the provider names, with site and laterality added for limb pain, myalgia and compartment syndrome. Fibromyalgia takes the single code M79.7, which the neighboring rheumatism, myalgia and compartment syndrome codes each exclude by an Excludes1 note.

When documentation says…

Code

Fibromyalgia

M79.7

Fibromyalgia. The Alphabetic Index sends Fibromyalgia here with no subterms. The note must state fibromyalgia as the provider's diagnosis. Guideline I.A.19 bases code assignment on that statement, not on the clinical criteria behind it.

Fibrositis, fibromyositis or myofibrositis

M79.7

Fibromyalgia. All three terms are M79.7 inclusion terms. The Index sends each one here. The Index has two exceptions. Myofibrositis, scapulohumeral says see Lesion, shoulder, specified NEC. Fibrositis, nodular, chronic says see Arthropathy, postrheumatic, chronic.

Muscle pain or myalgia, no fibromyalgia diagnosis

M79.10

Myalgia, unspecified site. The Index sends Myalgia here, with M79.11, M79.12 and M79.18 for named sites. Subcategory M79.1 carries an Excludes1 note for fibromyalgia (M79.7).

Myofascial pain syndrome

M79.18

Myalgia, other site. The Index sends Syndrome, myofascial pain and Pain, myofascial here. Myofascial pain syndrome is an inclusion term at M79.1, which excludes fibromyalgia.

Rheumatism, no further detail

M79.0

Rheumatism, unspecified. The Index sends Rheumatism (articular) (neuralgic) (nonarticular) here. M79.0 carries an Excludes1 note for fibromyalgia (M79.7) and palindromic rheumatism.

Soft tissue pain the provider calls psychogenic

F45.41

Pain disorder exclusively related to psychological factors. Category M79 carries an Excludes1 note for soft tissue pain, psychogenic (F45.41). The Index sends Pain, psychogenic here.

Chronic fatigue syndrome or ME/CFS

G93.32

Myalgic encephalomyelitis/chronic fatigue syndrome. The Index sends Syndrome, fatigue, chronic here. No Excludes note links G93.32 and M79.7. Both are reported when the provider diagnoses both conditions.

Tabular notes

INCLUSION TERMS

M79.7 lists three inclusion terms: fibromyositis, fibrositis and myofibrositis.

The Alphabetic Index sends Fibromyalgia, Fibromyositis, Fibrositis (periarticular) and Myofibrositis to M79.7.

EXCLUDES1

M79.7 carries no Excludes1 note of its own.

Category M79 carries an Excludes1 note for psychogenic rheumatism (F45.8) and soft tissue pain, psychogenic (F45.41). Neither is reported together with M79.7 for the same condition.

Four notes run in the other direction. M79.0, subcategory M79.1, subcategory M79.A and subcategory T79.A each carry an Excludes1 note for fibromyalgia (M79.7).

Guideline I.A.12.a allows both codes of an Excludes1 pair when the two conditions are unrelated. If it is not clear whether they are related, query the provider.

EXCLUDES2

M79.7 and category M79 carry no Excludes2 note. The M70-M79 block carries none either.

Chapter 13 carries an Excludes2 note for certain infectious and parasitic diseases (A00-B99), endocrine, nutritional and metabolic diseases (E00-E88), neoplasms (C00-D49) and injury, poisoning and certain other consequences of external causes (S00-T88).

The same note lists arthropathic psoriasis (L40.5-), compartment syndrome (traumatic) (T79.A-), certain conditions originating in the perinatal period (P04-P96) and complications of pregnancy, childbirth and the puerperium (O00-O9A).

It also lists congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99) and symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94).

Excludes2 means the patient may have both conditions at the same time.

USE ADDITIONAL

M79.7, category M79 and the M70-M79 block carry no use additional code, code first or code also instruction.

Chapter 13 carries a note to use an external cause code following the code for the musculoskeletal condition, if applicable, to identify the cause.

No tabular note ties M79.7 to a depression, anxiety, fatigue or sleep code.

FY2027: EFFECTIVE 1 OCTOBER 2026

The FY2027 codes addenda make no addition, deletion or revision in category M79. M79.7 is in the FY2027 billable code list and is unchanged in the FY2027 update.

The M79, M79.0, M79.1, M79.7 and M79.A notes read the same in the FY2027 tabular as in the April 2026 release.

Operational & financial impact

Why specificity matters beyond the chart: risk adjustment, DRG assignment and denial exposure all follow from which code is selected.

CMS-HCC v28 (PY2024+)

No code in category M79 appears in the CMS-HCC v28 diagnosis crosswalk. G89.4, G89.29, F45.41 and the M60 myositis codes are absent from it as well.

G93.32 is absent from the bundled FY2022 to FY2023 crosswalk file, which omits some recent codes. Its v28 mapping is indeterminate.

MS-DRG v44 (FY2027)

MS-DRG 555: Signs and symptoms of musculoskeletal system and connective tissue with MCC.

MS-DRG 556: Signs and symptoms of musculoskeletal system and connective tissue without MCC.

M79.7 as principal diagnosis groups to one of these two DRGs in MDC 08, per the CMS MS-DRG v44.0 Definitions Manual, Appendix B.

M62.838, M79.671 and M79.672 group to the same two DRGs as principal diagnosis. G89.29 groups to MS-DRG 091 to 093, Other disorders of nervous system. G93.32 groups to MS-DRG 947 and 948, Signs and symptoms.

WHERE SPECIFICITY IS LOST

Reporting a myalgia code for pain the provider diagnoses as fibromyalgia conflicts with the M79.1 Excludes1 note.

Reporting R52 or a pain by site code for pain the provider attributes to fibromyalgia replaces the diagnosis with a symptom. Guideline I.B.5 says signs and symptoms routinely associated with a disease process are not coded additionally.

Reporting M79.7 for fibromyalgia documented only as probable or suspected in an outpatient note conflicts with Section IV.H. The symptoms are coded instead.

SEVERITY DESIGNATION (MS-DRG V44, FY2027)

M79.7 is on neither list. It carries no CC or MCC designation as a secondary diagnosis.

In category M79, only the nontraumatic compartment syndrome codes in subcategory M79.A are CCs.

Per Table 6I (Complete MCC List) and Table 6J (Complete CC List) of the FY2027 IPPS final rule (CMS-1849-F), MS-DRG v44.

Documentation checklist to support M79.7

Chart elements that support code selection and reduce specificity-driven denials.

The provider's diagnostic statement of fibromyalgia, fibrositis, fibromyositis or myofibrositis. Guideline I.A.19 makes that statement sufficient for code assignment.

For outpatient encounters, a confirmed diagnosis. Fibromyalgia documented as probable, suspected or rule out is not coded. The symptoms are coded instead (Section IV.H).

Whether the provider describes localized muscle pain or myofascial pain syndrome rather than fibromyalgia, which moves the code to M79.10 or M79.18.

Whether the provider calls the soft tissue pain psychogenic, which moves the code to F45.41 under the M79 Excludes1 note.

Whether the provider specifically documents chronic pain syndrome, which supports G89.4 (Guideline I.C.6.b.6).

Whether the encounter is for pain control or pain management, which decides whether a G89 code may be added (Guideline I.C.6.b.1).

A separate diagnosis of chronic fatigue syndrome or ME/CFS, which adds G93.32.

Any other condition the provider documents as a separate diagnosis that affects care, each coded on its own documentation (Section IV.J).

For inpatient stays, a diagnosis documented as probable or suspected at discharge is coded as if established (Sections II.H and III.C).

FAQ

Is M79.7 a billable code?

Yes. M79.7 is a complete code with no further characters. It appears in the FY2027 billable code list. Its parent, category M79, is a header and cannot be reported.

What is the ICD-10 code for fibromyalgia?

M79.7, Fibromyalgia. The Alphabetic Index sends Fibromyalgia to M79.7 with no subterms. Fibrositis, fibromyositis and myofibrositis are M79.7 inclusion terms and code here as well.

What is the difference between M79.7 and the myalgia codes in M79.1?

M79.1 holds myalgia by site. Its inclusion term is myofascial pain syndrome. The Index sends Myalgia to M79.10 and Syndrome, myofascial pain to M79.18. Subcategory M79.1 carries an Excludes1 note for fibromyalgia (M79.7). The two are not reported together for the same condition.

Does M79.7 map to an HCC under CMS-HCC v28?

No. M79.7 does not appear in the CMS-HCC v28 diagnosis crosswalk. No other M79 code appears in it either.

Can M79.7 be reported with G89.4 or G89.29?

No Excludes note links M79.7 with either code. Guideline I.C.6.b.6 allows G89.4 only when the provider specifically documents chronic pain syndrome. Guideline I.C.6.b.1 bars a G89 code when the underlying diagnosis is known, unless the encounter is for pain control or management.

Is there a code for fibromyalgia with depression, fatigue or sleep problems?

No. The Index lists Fibromyalgia with no subterms. No combination code exists for it. No tabular note ties M79.7 to a depression, fatigue or sleep code. A coexisting condition that requires or affects care is coded separately (Section IV.J). Chronic fatigue syndrome takes G93.32.

Can M79.7 be an inpatient principal diagnosis, and what changes in the outpatient setting?

As principal diagnosis, M79.7 groups to MS-DRG 555 or 556 under the FY2027 v44 grouper. On the inpatient side, a diagnosis documented as probable at discharge is coded as if established (Section II.H). In the outpatient setting it is not coded. The symptoms are reported instead (Section IV.H).

Did M79.7 change in FY2027?

No. The FY2027 codes addenda, effective 1 October 2026, make no addition, deletion or revision in category M79. The M79.7 inclusion terms and the M79 Excludes1 note read the same as in the April 2026 release.

Related codes

Codes in the same family as M79.7. Only codes with a published page render as links.

Sibling codes in the M79 family

M79.0: Rheumatism, unspecified, which excludes fibromyalgia.
M79.10: Myalgia, unspecified site, for muscle pain without a fibromyalgia diagnosis.
M79.11: Myalgia of mastication muscle.
M79.12: Myalgia of auxiliary muscles, head and neck.
M79.18: Myalgia, other site, where the Index sends myofascial pain syndrome.
M79.2: Neuralgia and neuritis, unspecified.
M79.89: Other specified soft tissue disorders, where polyalgia is an inclusion term.
M79.9: Soft tissue disorder, unspecified.
M79.609: Pain in unspecified limb.

Additional codes to consider

Codes outside the M79 family considered alongside M79.7.

Consider instead

M79.10: Myalgia, unspecified site, when the provider documents muscle pain or myalgia without diagnosing fibromyalgia.
M79.18: Myalgia, other site, when myofascial pain syndrome is documented.
M79.89: Other specified soft tissue disorders, when the provider documents polyalgia.
M60.9: Myositis, unspecified, when the provider documents myositis, which M79.1 also excludes.
M35.3: Polymyalgia rheumatica, when the provider documents polymyalgia rheumatica.
F45.41: Pain disorder exclusively related to psychological factors, when psychogenic soft tissue pain is documented.
F45.8: Other somatoform disorders, when psychogenic rheumatism is documented.
G93.32: Myalgic encephalomyelitis/chronic fatigue syndrome, when the provider diagnoses chronic fatigue syndrome.
G89.4: Chronic pain syndrome, only when the provider specifically documents chronic pain syndrome.

Sources

All claims on this page derive from government and professional-standards sources.

National Center for Health Statistics. (2026). International classification of diseases, tenth revision, clinical modification (ICD-10-CM) FY2027 files. https://www.cdc.gov/nchs/icd/icd-10-cm/files.html
Centers for Medicare & Medicaid Services and National Center for Health Statistics. (2026). ICD-10-CM official guidelines for coding and reporting FY2027. https://ftp.cdc.gov/pub/Health_Statistics/NCHS/Publications/ICD10CM/2027/ICD-10-CM-October-1-2026-FY27-Guidelines.pdf
Centers for Medicare & Medicaid Services. (2025). 2026 model software/ICD-10 mappings. https://www.cms.gov/medicare/payment/medicare-advantage-rates-statistics/risk-adjustment/2026-model-software-icd-10-mappings
Centers for Medicare & Medicaid Services. (2026). MS-DRG classifications and software, version 44. https://www.cms.gov/medicare/payment/prospective-payment-systems/acute-inpatient-pps/ms-drg-classifications-and-software