Losec is used to treat diseases that are related to excess acid in the stomach. These include:

• Gastroesophageal reflux disease or GERD (backflow of acid from the stomach into the oesophagus), causing heartburn and oesophagitis (inflammation of the swallowing pipe).
  
  
• Stomach ulcers (see peptic ulcers) and acid-related indigestion (dyspepsia), which is discomfort following meals.
  
  
• Losec is also used in combination with antibiotics to treat and help to heal ulcers associated with stomach infection by the microscopic bug (bacterium) called Helicobacter pylori.
  
  
• It is used to treat a rare illness called Zollinger-Ellison syndrome (a disease associated with ulcers and severely increased production of acid in the stomach).