Antacids are used to relieve gastric pain. Antacids, an alkali, neutralizes the gastric acids present in the stomach and raises the gastric pH. They contain aluminum hydroxide, magnesium carbonate and magnesium trisilicate. Antacids can also be used to reduce the symptoms of acid reflux which may cause heartburn or inflammation of the oesophagus. They can also relieve some of the symptoms caused by ulcers in the duodenum.