Gastro-oesophageal reflux is stomach acid flowing from the stomach back into the food pipe (oesophagus). Various conditions can cause reflux as a result of the pressure they exert on the stomach, for example, pregnancy and hiatus hernia. Reflux can cause symptoms such as indigestion, acid regurgitation, or the painful burning sensation of heartburn. Over long periods of time the acid can also damage and inflame the lining of the foodpipe. This condition is known as reflux oesophagitis.