Alphabetic Index FY2027

G43.C1

Periodic headache syndromes in child or adult, intractable

FY2027Chapter 6: Diseases of the nervous system/G40–G47 Episodic and paroxysmal disorders

BillableComplete code, valid to report
Care settingsHome Health Primary · MMTA - Other

G43.C1 (also written G43C1) is a billable ICD-10-CM diagnosis code for periodic headache syndromes in child or adult, intractable. It is part of the FY2027 code set, effective October 1, 2026. It is one of the 48 codes in category G43 (Migraine). The Alphabetic Index lists it under 2 entries. Its coding notes include a Use additional code instruction, 1 Excludes1 entry and 10 Excludes2 entries.

Use additional code

Add the listed code as a secondary code, if known.

Inherited from G43 Migraine
  • code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)

Excludes1

Not coded here. The listed conditions generally should not be reported together.

Inherited from G43 Migraine

Excludes2

Not included here. Both codes may be reported if the patient has both conditions.

Inherited from G43 Migraine
Also from chapter/block level (8 notes)
Inherited from Chapter 6 Diseases of the nervous system
  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)

Care settings

How CMS programs treat this code. These are CMS claim edits and list entries, not coverage or eligibility rules.

Home Health Primary

Accepted as the primary (principal) diagnosis on a home health claim. The Home Health Grouper assigns it to the MMTA - Other clinical group.

Source: CMS Home Health Grouper Software v07.2.26, effective October 1, 2026

Inclusion terms

Conditions classified to this code.

This code
  • Periodic headache syndromes in child or adult, with refractory migraine

Notes

Inherited from G43 Migraine
  • the following terms are to be considered equivalent to intractable: pharmacoresistant (pharmacologically resistant), treatment resistant, refractory (medically) and poorly controlled

Alphabetic Index terms

Terms the official Alphabetic Index lists for this code. 2 entries