Omeprazole belongs to the group of drugs that protect the gastric mucosa and can be secreted into breast milk, but there are no clinical data on the effect of omeprazole on breastfed infants or on lactation. It is recommended to take this drug as prescribed by the doctor. Omeprazole mainly has the effect of inhibiting gastric acid secretion, hemostasis and promoting the repair of gastric and duodenal mucosa, clinically, it is mainly used in the treatment of gastric and duodenal ulcers. Omeprazole is mainly digested and absorbed in the stomach, then inactivated by the liver, and finally excreted from the body by the kidneys. While considering breastfeeding for the development and health of infants and young children, the clinical need for the product in the mother and the potential adverse effects of the product or of the underlying maternal disease on breastfed infants and young children should be weighed, and the product should be used only if the benefits outweigh the potential risks. It is recommended that patients with gastrointestinal disorders should be treated as prescribed by their physician and should not take omeprazole without authorization. Breastfeeding women should take the medication in strict accordance with medical advice.