Dyspepsia and reflux. Artwork of the effects of antacids in preventing acid reflux and dyspepsia (indigestion). The stomach is seen as a wire-frame model. Antacids (white arrows) are drugs which neutralise stomach acid. Gastro-oesophageal acid reflux (inset, upper left) occurs when stomach juices escape from the mucus-lined stomach into the oesophagus, causing pain from the chest to the throat. It may be due to a hiatus hernia, in which part of the stomach protrudes through the oesoph- agus' opening in the diaphragm. The inset at lower right shows a secretory cell, which may produce acid or mucus. Drugs affecting the production of these may also be used to treat stomach pain.