Black period blood generally means that the blood is older and has taken longer to leave the uterus, causing it to oxidize and darken in color. This dark or black blood often appears at the beginning or end of a menstrual period when the flow is slower, allowing the blood to linger and oxidize, which is a normal and harmless process

. Common reasons for black period blood include:

• End or start of the menstrual cycle: Blood that stays longer in the uterus oxidizes and appears black or dark brown

• Hormonal fluctuations: Stress, changes in contraception, or conditions like PCOS can delay menstrual flow, causing older blood to be expelled later and appear darker

• Uterine or vaginal issues: Sometimes, black blood may indicate the presence of uterine fibroids, polyps, infections, or retained foreign objects, especially if accompanied by pain, foul odor, or irregular bleeding

• Structural uterine differences or history of cesarean section: These can cause blood to stagnate longer, leading to black menstrual blood

When to see a doctor:

• If black blood lasts longer than usual or is accompanied by severe pain, foul odor, fever, or other unusual symptoms.
• If there are irregular cycles, heavy bleeding, or signs of infection

In summary, black period blood is usually just older, oxidized blood and is typically not a cause for concern unless accompanied by other symptoms or persistent changes in your menstrual cycle. Consulting a healthcare provider is recommended if you experience additional symptoms or irregularities