Esomeprazole, sold under the brand name Nexium (or Neksium) among others,[1] is a medication which reduces stomach acid. It is used to treat gastroesophageal reflux disease, peptic ulcer disease, and Zollinger–Ellison syndrome.[9] Its effectiveness is similar to that of other proton pump inhibitors (PPIs).[10] It is taken by mouth or injection into a vein.
Common side effects include headache, constipation, dry mouth, and abdominal pain. Serious side effects may include angioedema, Clostridioides difficile infection, and pneumonia. Use in pregnancy appears to be safe, while safety during breastfeeding is unclear.[11] Esomeprazole is the (S)-(−)-enantiomer (or less specifically the S-isomer) of omeprazole. It works by blocking H+/K+-ATPase