The goal of this clinical trial is to identify the most effective way to take acid-blocking medications to treat stomach ulcers in patients who have undergone gastric bypass surgery. The main questions it aims to answer are:

• is taking an acid-blocking medication by opening the capsule and only taking the contents of the capsule (open-capsule) more or less effective than taking the capsule as a whole (intact-capsule) for treating ulcers in patients who have a history of gastric bypass surgery?
• does taking the open versus intact medication decrease the number of procedures and complications from untreated ulcers?

Participants with ulcers will be instructed to take acid-blocking medications (called proton-pump inhibitors) either by opening the capsule and taking only the contents or by taking the capsule whole. These medications are the gold standard for treatment of stomach ulcers. Participants will be asked to undergo an upper endoscopy (EGD) every 3 months to monitor the healing of the ulcers.

Researchers will compare how quickly the ulcers heal depending on which way the medications are taken (opened up or as a whole).

Marginal ulcers (ulcers formed at the surgery site between the stomach and the intestines) are a common complication of bariatric surgery, ranging in frequency from 0.6-25% of patients. Furthermore, roughly 17% of patients with marginal ulcers require repeat procedures or surgery for severe complications such as bleeding, perforation, stricture, and fistulas.

Proton pump inhibitors (PPIs), which act by block acid secretion from the stomach, are the gold standard for treatment of ulcers. There is limited data showing that opening the PPI capsule and taking only the contents greatly improves healing of marginal ulcers after gastric bypass surgery. This is likely due to the much smaller stomach, faster passage through the stomach and decreased ability of the intact PPI medication to be broken down and absorbed.

This would be the first clinical trial to confirm whether this is true, which would support all patients who get ulcers after gastric bypass surgery to be treated with open-capsule PPI medications.

Inclusion Criteria:

• Subjects diagnosed with marginal ulceration post-gastric bypass on upper endoscopy

Exclusion Criteria:

• Refusal to start PPI medication OR current open-capsule PPI use at the time of diagnosis of the marginal ulcer

Endoscopists diagnosing and surveying healing of marginal ulcers will be blinded to the subject's treatment arm. A single, unmasked provider will be responsible for randomizing and prescribing either open- or intact-capsule PPI after subjects are enrolled in the study. This unmasked provider will not take part in diagnosis, monitoring or assessment of ulcer healing, or in data analysis.