Ferrous sulfate is a clinically used iron-containing drug, mainly for iron supplementation, which can be used for patients with iron deficiency anemia caused by various reasons. The side effects of oral ferrous sulfate mainly include the following: 1. Gastrointestinal irritation symptoms, some patients may experience nausea, vomiting, epigastric pain and discomfort after taking ferrous sulfate, which can be started in small doses and taken during or after meals to reduce Gastrointestinal reactions. 2, oral administration of ferrous sulfate will cause patients to reduce intestinal motility, constipation, black stool symptoms. 3, allergic reactions, a small number of patients taking ferrous sulfate may experience allergic reactions, such as itchy skin, rashes and other drug allergies. 4, aggravated liver and kidney damage, liver and kidney insufficiency in patients after oral administration of ferrous sulfate, may aggravate the symptoms of liver and kidney damage.