ICD-10-CM 2027
ICD-10 code for esophageal reflux
From the official ICD-10-CM alphabetic index entry “Reflux › esophageal”. Page updated September 29, 2026.
About coding esophageal reflux
The ICD-10-CM code for esophageal reflux is K21.9 (Gastro-esophageal reflux disease without esophagitis). The official index lists 3 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on K21.9.
Within K21, choose K21.9 (without esophagitis) only when documentation doesn't support a more specific option: with esophagitis (K21.0).
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 391 (Esophagitis, Gastroenteritis and Miscellaneous Digestive Disorders with MCC, relative weight 1.2392) and DRG 392 (Esophagitis, Gastroenteritis and Miscellaneous Digestive Disorders without MCC, relative weight 0.7645), in MDC 06 (Diseases and Disorders of the Digestive 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.
More specific esophageal reflux codes (official index)
Common questions about esophageal reflux ICD-10 codes
What is the ICD-10 code for esophageal reflux?
- K21.9 — Gastro-esophageal reflux disease without esophagitis. More specific codes apply when the documentation supports them: K21.00, K21.01, P78.83.
What is the ICD-10 code for newborn esophageal reflux?
- P78.83 — Newborn esophageal reflux.
Is K21.9 billable?
- Yes. K21.9 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can K21.9 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict K21.9 as a principal diagnosis.
Is K21.9 a CC or MCC?
- No. K21.9 is neither a CC nor an MCC under MS-DRG v44.0.