ICD-10-CM 2027 diagnosis code
G43.C1Periodic headache syndromes in child or adult, intractable
G43.C1 is a valid, billable ICD-10-CM code for periodic headache syndromes in child or adult, intractable. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.
Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data
About G43.C1
G43.C1 is the ICD-10-CM diagnosis code for periodic headache syndromes in child or adult, intractable. It belongs to category G43 (migraine), block G40-G47 (episodic and paroxysmal disorders) and chapter 6 (diseases of the nervous system). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.
Within G43.C (periodic headache syndromes in child or adult), G43.C1 is specifically for periodic headache syndromes in child or adult, intractable. Related codes cover not intractable (G43.C0).
Use an additional code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5).
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
In MS-DRG v44.0, it is part of the grouping logic for DRG 102 (Headaches with MCC, relative weight 1.1201) and DRG 103 (Headaches without MCC, relative weight 0.822), in MDC 01 (Diseases and Disorders of the Nervous System), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.
Before ICD-10, this condition was coded in ICD-9-CM as 346.21 (variants of migraine, not elsewhere classified, with intractable migraine, so stated, without mention of status migrainosus).
Coding notes
- Periodic headache syndromes in child or adult, with refractory migraine
Notes that apply from higher levels
Instructions written at a parent level also apply to G43.C1.
› From G43 Migraine
- the following terms are to be considered equivalent to intractable: pharmacoresistant (pharmacologically resistant), treatment resistant, refractory (medically) and poorly controlled
- lower half migraine (G44.00)
Broader instructions also apply from Chapter 6: Diseases of the nervous system.
Alphabetic index entries
2 entriesTerms in the official ICD-10-CM index that lead to G43.C1.
MS-DRG v44.0 grouping
All DRGs →Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.
MDC 01 · Diseases and Disorders of the Nervous System
ICD-9-CM equivalent
Converter →- 346.21Variants of migraine, not elsewhere classified, with intractable migraine, so stated, without mention of status migrainosusapproximate
From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.
Code history
- 2016
- 2017
- 2018
- 2019
- 2020
- 2021
- 2022
- 2023
- 2024
- 2025
- 2026
- 2027
- FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
- No changes since FY2016.
Common questions about G43.C1
Is G43.C1 billable?
- Yes. G43.C1 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can G43.C1 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict G43.C1 as a principal diagnosis.
Is G43.C1 a CC or MCC?
- No. G43.C1 is neither a CC nor an MCC under MS-DRG v44.0.
What DRG does G43.C1 group to?
- G43.C1 is used in the MS-DRG v44.0 logic for MS-DRG 102 (Headaches with MCC) and MS-DRG 103 (Headaches without MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.
What is the ICD-9 code for G43.C1?
- The CMS General Equivalence Mappings map G43.C1 to ICD-9-CM 346.21.