Zocdoc Answers

Medical questions & health advice by licensed doctors

"Why do I see black blood in the middle of my cycle?"

ZocdocAnswersWhy do I see black blood in the middle of my cycle?


Sometimes there are stains on my underwear midcycle. Is this normal? I am on birth control if that helps.


A healthy vagina secretes normal discharges that regulate and keep infections at bay. These discharges can range from clear to yellowish or cloudy white. One of the most frequently experienced gynecological symptoms is abnormal vaginal discharge. A vaginal discharge varies due to such things as the menstrual cycle, birth control pills, nutrition and pregnancy. Variation from normal can indicate an infection or disease. Although birth control is not 100 percent preventing pregnancy, let us exclude the possibility of an early pregnancy that is associated with implantation bleeding which releases a dark brown or black discharge. You have stated that you are on birth control. When you start on a new form of birth control, spotting between periods can be a normal occurrence only if it is in the first few months. Another totally normal possibility for the black discharge is the old endometrial tissues or uterine lining that for whatever reason during your last period failed to make a timely exit. Such spotting blood stays long enough inside your uterus to be oxidized to black blood which is expelled as a way of "cleaning out" your vagina. On the other hand, persistent abnormal vaginal discharge can be a sign of a serious condition. Bacterial vaginosis occurs when bacteria that normally live in the vagina overgrow, causing a milky or grey discharge. Some other common conditions causing brown or black discharge include cervical cancer, pelvic inflammatory disease, sexually transmitted diseases (i.e., gonorrhea, chlamydia or vaginal warts), or simply a forgotten tampon. As with any medical concern it is best to visit a gynecologist to evaluate if the problem is serious or due to a non-issue such as left-over endometrial tissues or an effect of birth control pills.

Zocdoc Answers is for general informational purposes only and is not a substitute for professional medical advice. If you think you may have a medical emergency, call your doctor (in the United States) 911 immediately. Always seek the advice of your doctor before starting or changing treatment. Medical professionals who provide responses to health-related questions are intended third party beneficiaries with certain rights under Zocdoc’s Terms of Service.