Metformin can be taken during menstruation without much effect on the body. Metformin is mostly used clinically for the treatment of type 2 diabetes, in addition to diabetes, metformin is mainly used in obstetrics and gynecology for the treatment of polycystic ovary syndrome, by improving insulin resistance, and then improve the symptoms of hirsutism and menstrual irregularities in insulin patients. In addition, metformin has the effect of inducing ovulation and increasing the chance of conception, and has become the first-line drug for the treatment of polycystic ovary syndrome in clinical practice. The most common adverse effects of metformin are gastrointestinal reactions, including nausea, vomiting, diarrhea, and abdominal distention. Metformin can be taken normally during menstruation without adverse effects on the body, but it is not recommended when there are: 1, moderate to severe renal insufficiency; 2, hypoxic diseases; 3, severe infections and trauma; 4, allergy to metformin; 5, acute and chronic metabolic acidosis; 6, alcoholics; 7, patients receiving intravascular injections of iodinated contrast media; 8, vitamin B12, folic acid deficiency, uncorrected patients.