What causes black blood?

What causes black blood? Black. Black blood can appear at the beginning or end of a person’s period. The color is typically a sign of old blood or blood that has taken longer to leave the uterus and has had time to oxidize, first turning brown or dark red and then eventually becoming black.

Black. Black blood can appear at the beginning or end of a person’s period. The color is typically a sign of old blood or blood that has taken longer to leave the uterus and has had time to oxidize, first turning brown or dark red and then eventually becoming black.