Inflammation of the mucous membrane of the oesophagus, often caused by chronic gastric acid irritation; the stomach is not affected by this acid, but the oesophagal mucous membrane is. Normally there is no gastric juice in the oesophagus, but if the valve mechanism at the entrance to the stomach is not functioning properly, some acid may flow back (so-called reflux), when the condition is known as reflux inflammation of the oesophagus. Inflammation also occurs as a result of tumours or stricture, and after accidentally drinking corrosive liquids. Gastric acid reflux causes heartburn and pain behind the breastbone, sometimes associated with regurgitation of food. Discomfort increases with lying, bending, straining and lifting, and also in cases of overweight, pregnancy, and excessive smoking.