Causes of Black Menstrual Blood

Normal menstrual blood is dark red in color and occurs regularly each month. Menstruation begins at puberty and continues for several decades throughout a woman’s life. However, menstrual cycles are highly susceptible to abnormalities, with abnormal coloration being one of the most common manifestations. In daily life, some women notice that their menstrual blood appears black—significantly different from its usual appearance—prompting natural concern about the underlying cause. Below, we address this issue.

Why Is Menstrual Blood Black?

Black menstrual blood is commonly associated with qi stagnation and blood stasis—a leading cause of menstrual irregularities among modern women. Excessive life stress, irregular lifestyle habits, introverted personality traits, anxiety, depression, and other negative emotions that remain unexpressed can all contribute to liver qi stagnation and impaired blood circulation, resulting in menstrual disorders and dysmenorrhea—conditions that are extremely prevalent.

If menstrual blood remains consistently dark red throughout the entire period and is accompanied by an unusually large number of clots, this is considered abnormal. Similarly, the presence of symptoms such as nausea, vomiting, abdominal pain, or even shock during menstruation also indicates abnormal menstruation. Occasional deviations from normal patterns may be harmless; however, persistent abnormalities occurring for two consecutive months or longer warrant medical attention.

Knowledge Extension: What Should Be Done If Menstrual Blood Appears Black?

Black menstrual blood typically suggests inadequate warmth in the lower abdomen during menstruation, leading to cold invasion—or excessive consumption of raw, cold foods during the period—which causes blood stasis and darkening of menstrual flow. It is essential to keep the lower abdomen warm and avoid cold exposure. Drinking ginger and brown sugar tea regularly may help alleviate symptoms; alternatively, under a physician’s guidance, motherwort (Leonurus japonicus) and brown sugar tea may also be beneficial.

In some cases, black menstrual blood may indicate underlying gynecological inflammation—for example, endometritis, salpingo-oophoritis (adnexitis), or cervicitis. Women experiencing this symptom should consult a gynecologist 3–5 days after menstruation ends. A comprehensive evaluation—including gynecological examination and pelvic ultrasound—is recommended to confirm or rule out inflammatory conditions. Once diagnosed, targeted treatment should be initiated under medical supervision. For confirmed endometritis or adnexitis, appropriate antibiotics (based on sensitivity testing) combined with herbal preparations such as Jinji Capsules may be prescribed.

The above outlines the primary causes of black menstrual blood. We hope this information proves helpful to you.