GERD is K21 — the last digit tells you if there's damage
In ICD-10, gastro-esophageal reflux disease lives under K21 in the "diseases of the esophagus, stomach and duodenum" chapter. The number after the dot answers one question: has the reflux visibly inflamed your esophagus?
Reflux disease diagnosed from symptoms (frequent heartburn, regurgitation) with no confirmed inflammation — either no endoscopy yet, or a normal-looking esophagus (NERD, non-erosive reflux disease). The most common GERD code.
An endoscopy or biopsy has shown reflux esophagitis: inflammation, erosions or mucosal breaks in the esophageal lining. In ICD-10-CM (US) it splits into K21.00 without bleeding and K21.01 with bleeding.
My experience: after years of "just acidity" my endoscopy report read K21.0 — GERD with esophagitis, with a severe mucosal break at the esophagus–stomach junction. The code was the moment it stopped being a nuisance and became a diagnosis. Read the full story →
Related ICD-10 codes you may see
- R12 — Heartburn as a symptom only, before any reflux diagnosis. Heartburn explained →
- K20 — Esophagitis from causes other than reflux (K20.0 eosinophilic, K20.8 other, K20.9 unspecified).
- K22.1 — Ulcer of esophagus (K22.10 without bleeding, K22.11 with bleeding).
- K22.2 — Esophageal obstruction / stricture, a possible GERD complication.
- K22.7 — Barrett's esophagus (K22.70 without dysplasia, K22.71 with dysplasia).
- K44 — Diaphragmatic (hiatal) hernia, often coded alongside GERD (K44.9 without obstruction or gangrene).
- K30 — Functional dyspepsia (indigestion), sometimes used when reflux isn't confirmed.
Is there an ICD-10 code for acid reflux?
Not a separate one. Occasional acid reflux that's bothersome enough to code is recorded as K21.9. If only the symptom is documented, R12 (heartburn) may be used instead.
Why the code matters to you
- Treatment intensity: K21.0 usually means a full healing course of medicine and a follow-up scope; K21.9 often starts with lifestyle changes and a trial of medicine. GERD treatment →
- Insurance and referrals: the code justifies endoscopy, specialist visits and ongoing treatment.
- Your own records: knowing your code helps you ask the right questions — "was there esophagitis?", "what grade?", "do I need a repeat endoscopy?"
Note: codes are assigned by clinicians and coders; this page is for understanding your paperwork, not for self-diagnosis or billing. Systems differ slightly between ICD-10 (WHO), ICD-10-CM (US) and national variants.
What to do next
Whichever code is on your report, the cause is the same: acid reaching the esophagus too often. Why that happens → · GERD symptoms → · GERD diet →
This page shares personal experience and general information. It is not medical advice — please consult your doctor about your own condition.