It is possible to take folic acid during menstruation. If the patient is using folic acid to prepare for pregnancy, she should take folic acid at a dose of 0.4 mg/d during the first trimester of pregnancy, and she should take it every day without stopping it during menstruation. If the patient is using folic acid to treat anemia caused by folic acid deficiency, it is not necessary to stop taking it during menstruation, but during the entire menstrual period and the entire period of anemia, without interruption, until the patient’s blood count is determined to have returned to normal. However, further examination must be done to determine the cause of folic acid deficiency and then systematically treat the cause, as anemia will soon appear again if not treated.