Nexium contains the active ingredient esomeprazole. This belongs to a group of medicines called ‘proton pump inhibitors’ (PPI\'s). They work by reducing the amount of acid that your stomach produces and thus protecting the oesophagus from exposure to excess acid. Nexium is the original branded version of esomeprazole which is now available as a generic. It is effective in treating GERD symptoms including heartburn and indigestion. It is also used in patients who have stomach ulcers caused by NSAID uses and Helicobacter Pylori infection.