Taking an omeprazole capsule three to five days may be harmful. Omeprazole belongs to proton pump inhibitors, which can be used to treat acid reflux, heartburn, epigastric pain and other symptoms caused by diseases of the upper gastrointestinal tract such as gastric ulcers, duodenal ulcers, reflux esophagitis, Helicobacter pylori infections, upper gastrointestinal bleeding and other diseases of the upper gastrointestinal tract by inhibiting the secretion of gastric acid. Omeprazole may lead to allergies, liver and kidney function damage, headache, nausea, vomiting, diarrhea, constipation and other side effects, so three or five days of omeprazole may have a certain harm, and personal constitution and disease conditions also have a certain relationship. If there is a stomach disease is not recommended to take omeprazole on their own, it is recommended to check the gastroscopy and other items, follow the doctor’s instructions to take medication.