Esomeprazole is a proton pump inhibitor (PPI) medication used to treat gastroesophageal reflux disease (GERD), a condition where stomach acid flows back into the esophagus and causes heartburn. It works by reducing the amount of acid produced in the stomach. It is also used to treat other conditions such as Zollinger-Ellison syndrome, a rare condition where the stomach produces too much acid. Esomeprazole is available as a prescription drug and can be taken orally, usually once a day before a meal. 

Common side effects of esomeprazole include headaches, nausea, and diarrhoea. It is important to take esomeprazole exactly as prescribed by a doctor, as overuse or misuse of this medication can lead to serious health problems.

Further information about the medication:

https://www.nhs.uk/medicines/esomeprazole/