Ranitidine and omeprazole are both drugs that inhibit the secretion of gastric acid, and are mainly used in the treatment of acute gastritis, chronic gastritis and peptic ulcer. Ranitidine is an H2 receptor antagonist and omeprazole is a proton pump inhibitor, which is stronger in inhibiting the effect of gastric acid, including other proton pump inhibitors. Omeprazole is preferred for the treatment of peptic ulcers, because omeprazole or other proton pump inhibitors promote ulcer healing faster than H2 receptor antagonists, and the healing rate of ulcers is higher, so it is more suitable for the treatment of refractory ulcers, or ulcers caused by non-steroidal anti-inflammatory drugs. In the eradication of H. pylori, proton pump inhibitors, such as omeprazole, have a better synergy with antibiotics than ranitidine, so the use of PPIs is recommended as the basic drug in the eradication of HP regimen.