2027 ICD-10-CM Diagnosis Code G43.A1Cyclical vomiting, in migraine, intractable

ICD-10-CM Codes›G00–G99›G40-G47›G43

ICD-10-CM G43.A1
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

G43.A1 is a billable ICD-10-CM diagnosis code for cyclical vomiting, in migraine, intractable. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 102 through 103. Coders also document this condition as cyclical vomiting syndrome. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Headache; including migraine and Nausea and vomiting.

G43.A1 does not risk-adjust for Medicare Advantage under the CMS-HCC V28 model. It still risk-adjusts in the RxHCC Part D (V08) category 166 for payment year 2027.

Code Identity

ICD-10-CM Code
G43.A1
Billable Status
Yes — Valid for Submission
Code Describes
Cyclical vomiting, in migraine, intractable
Short Description
Cyclical vomiting, in migraine, intractable
Same as the full description in the CMS dataset.
Parent Code
G43.A
Cyclical vomiting

Code Classification

ChapterG00–G99Diseases of the nervous system
SectionG40-G47Episodic and paroxysmal disorders
CategoryG43Migraine
This CodeG43.A1Cyclical vomiting, in migraine, intractable

Medicare Risk Adjustment (HCC)Billing

G43.A1 does not risk-adjust for Medicare Advantage under the CMS-HCC V28 model, but it maps to payment categories in the other CMS models shown below.

CMS-HCC V28 (Medicare Advantage Payment Model)
Not mapped
no payment category in the model that pays 100% of MA risk scores
Prior Model (CMS-HCC V24)
Not mapped under V24
this diagnosis newly risk-adjusts under the V28 model
Part D (RxHCC)
RxHCC 166 — Migraine Headaches
also risk-adjusts in the Part D prescription drug model (V08)

Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Cyclical vomiting syndrome
  • Intractable cyclical vomiting syndrome

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to G43.A1: its own notes plus those printed at G43.A, G43, and Chapter 6. A note printed at a category, block or chapter applies to every code under it.

Applicable To

Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.

  • Cyclical vomiting, with refractory migraine

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From G43.A Cyclical vomiting applies to 2 codes
  • cyclical vomiting syndrome unrelated to migraine (R11.15)
From G43 Migraine applies to 48 codes

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From G43 Migraine applies to 48 codes
From Chapter 6 (G00-G99) Diseases of the nervous system applies to 700 codes
  • 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)

Use Additional Code

Add a second code, after this one, to fully describe the condition.

From G43 Migraine applies to 48 codes
  • code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)

Notes

General instructions on how these codes are used.

From G43 Migraine applies to 48 codes
  • the following terms are to be considered equivalent to intractable: pharmacoresistant (pharmacologically resistant), treatment resistant, refractory (medically) and poorly controlled

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name G43.A1, its category, or a range that includes it.

Excludes1 2

These codes carry an Excludes1 note naming G43.A1: they are not reported together with it, unless the two conditions are unrelated.

  • R11 Nausea and vomiting
    cyclical vomiting associated with migraine (G43.A-) names G43.A-, which includes this code
  • R11.15 Cyclical vomiting syndrome unrelated to migraine
    cyclical vomiting in migraine (G43.A-) names G43.A-, which includes this code

Excludes2 4

These codes carry an Excludes2 note naming G43.A1: its condition is not part of those codes, and both may be reported when the patient has both.

  • G44 Other headache syndromes
    migraines (G43.-) names G43.-, which includes this code
  • G44.1 Vascular headache, not elsewhere classified
    migraine (G43.-) names G43.-, which includes this code
  • G89 Pain, not elsewhere classified
    migraines (G43.-) names G43.-, which includes this code
  • R51 Headache
    migraine and other headache syndromes (G43-G44) names G43-G44, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

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

CCSR NVS010
Headache; including migraine
Default principal diagnosis: inpatient Yes · outpatient Yes
CCSR SYM004
Nausea and vomiting
Default principal diagnosis: inpatient No · outpatient No

Clinical InformationClinical

  • Cyclical Vomiting

    a condition characterized by recurrent, self-limiting episodes of vomiting associated with intense nausea, pallor, and lethargy. it is commonly a migraine precursor.

  • Migraine Disorders

    a class of disabling primary headache disorders, characterized by recurrent unilateral pulsatile headaches. the two major subtypes are common migraine (without aura) and classic migraine (with aura or neurological symptoms). (international classification of headache disorders, 2nd ed. cephalalgia 2004: suppl 1)

Patient EducationClinical

Nausea and Vomiting

Nausea is when you feel sick to your stomach, as if you are going to throw up. Vomiting is when you throw up.

The full article covers:

  • What are nausea and vomiting?
  • What causes nausea and vomiting?
  • When do I need to see a health care provider for nausea and vomiting?
  • How is the cause of nausea and vomiting diagnosed?
  • What are the treatments for nausea and vomiting?

Read the full article at MedlinePlus

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

Convert G43.A1 to ICD-9-CMHistory

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

ICD-9-CM
346.21 Vrnt mgrn w ntrc mgr NEC
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About G43.A1Overview

What is the ICD-10 code for cyclical vomiting, in migraine, intractable?

The ICD-10-CM code for cyclical vomiting, in migraine, intractable is G43.A1 (sometimes written as G43A1). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is G43.A1 (Cyclical vomiting) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report cyclical vomiting, in migraine, intractable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does G43.A1 group to?

When cyclical vomiting, in migraine, intractable is the principal diagnosis on an inpatient stay, it groups to MS-DRG 102, 103, with relative weights from 0.8219 to 1.1200 depending on complications. Higher weights mean higher Medicare reimbursement.

Can G43.A1 be reported with R11.15?

Not as a rule. The Excludes1 note at G43.A, which applies to G43.A1, lists "cyclical vomiting syndrome unrelated to migraine (R11.15)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).

Does G43.A1 need an additional code?

When the condition applies, yes. The Use Additional Code note at G43, which applies to G43.A1, reads: code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5). The additional code is reported after G43.A1.

Does G43.A1 risk-adjust for Medicare Advantage payment?

Not for Medicare Advantage: G43.A1 maps to no category in the CMS-HCC V28 model. It still risk-adjusts in the RxHCC Part D (V08) category 166 (Migraine Headaches).