Opioids are the gold standard for treatment of chronic and acute pain; however, their use may result in significant gastrointestinal side effects, including nausea, vomiting, and constipation. The reasons behind these side effects are not well understood. A new study reports on how opioids like morphine cause gastric inflammation and how this condition can be reversed through treatment with proton pump inhibitor drugs like omeprazole, an over-the-counter medication commonly used to reduce stomach acid.