The stomach makes acid which helps digest your food. Sometimes acid from your stomach flows back into your gullet or oesophagus. This can lead to conditions known as heartburn and acid indigestion that cause pain, a burning sensation in the chest and throat, an unsettled stomach or stomach pain.
Simple antacid medicines contain ingredients which neutralise the excess acid. Their effect does not last long and you may need to take them frequently and regularly to keep your symptoms under control.
Another form of treatment are H2-antagonists, also known as H2-blockers. They are a different way of treating the problems of heartburn and acid indigestion. Instead of just neutralising the excess acid, they work by preventing your stomach from producing too much acid in the first place.