K21.0: Gastro-oesophageal reflux disease with oesophagitis

There is gastric acid in your gullet. Your gullet has thus become inflamed as a result.

The oesophagus or gullet connects the mouth with the stomach. It is a muscular tube. The muscles in the oesophagus move food into the stomach. The oesophagus is usually closed by a sphincter muscle at the junction to the stomach. This is meant to prevent the stomach contents and gastric acid being regurgitated into the oesophagus. Only during swallowing does the oesophagus briefly open its sphincter muscle to the stomach.

The sphincter muscle between your gullet and stomach is not properly tight. Due to the leaky closure, gastric acid from the stomach is sometimes being regurgitated into the gullet. That may get worse when you are lying down or doing physical exertion.

The inside of the gullet is lined with mucous membrane. The gastric acid attacks the mucous membrane of the gullet. Your gullet has been inflamed by the gastric acid. As a result, you may have heartburn or a feeling of pressure in your chest. You may also have discomfort when swallowing or have to burp often.

If a lot of gastric acid is being produced it can also make the symptoms worse. Certain foodstuffs favor the formation of more gastric acid. Foodstuffs include coffee and alcohol, for example. More gastric acid can also be formed as a result of smoking or stress.

Additional indicator

On medical documents, the ICD code is often appended by letters that indicate the diagnostic certainty or the affected side of the body.

  • G: Confirmed diagnosis
  • V: Tentative diagnosis
  • Z: Condition after
  • A: Excluded diagnosis
  • L: Left
  • R: Right
  • B: Both sides

Further information


This information is not intended for self-diagnosis and does not replace professional medical advice from a doctor. If you find an ICD code on a personal medical document, please also note the additional indicator used for diagnostic confidence.
Your doctor will assist you with any health-related questions and explain the ICD diagnosis code to you in a direct consultation if necessary.


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