When you take folic acid, you bleed brown stuff. This brown stuff may be vaginal bleeding, which is usually not related to taking folic acid. Generally women who take folic acid will not vaginal bleeding, bleeding may be related to menstruation, pre-menstrual abortion, gynecological diseases. 1. Menstruation: If a woman takes folic acid and bleeds brown stuff, she may just meet her menstruation period, and the brown stuff is a small amount of menstrual blood. 2. Pre-eclampsia: pregnant women eat folic acid on the flow of brown stuff, may be pre-eclampsia, at this time there are abdominal pain and other symptoms, need to pay attention. 3. Gynecological diseases: not pregnant nor menstruation, women who take folic acid and then flow brown stuff, can consider gynecological diseases, such as vaginitis, endometrial hyperplasia and other causes of vaginal bleeding. If a woman takes folic acid and bleeds brown stuff, she needs to go to the hospital in time.