Dark period blood is often perfectly normal and usually isn't a cause for concern. The color of your menstrual blood can vary throughout your cycle, and several factors contribute to its darkness.
Why Does My Period Blood Appear Dark?
The primary reason for dark or brown period blood is oxidation. As blood sits in your uterus and vagina, it's exposed to oxygen. This exposure causes the blood to oxidize, changing its color from bright red to darker shades of red, brown, or even black. The longer the blood remains in your body, the darker it becomes. This is especially common at the beginning and end of your period because the blood flow is slower during these times. [1, 5, 8, 9, 10] The blood may also be leftover from your previous period. [1, 6]
When Should I Be Concerned About Dark Period Blood?
While dark period blood is usually normal, certain circumstances warrant medical attention. For example, consistently black blood could indicate a vaginal blockage. [4] If the dark color is unexpected, accompanied by other symptoms like intense pain, or if it's a significant change from your usual menstrual pattern, it's best to consult a healthcare professional. [4, 7]
What Other Factors Affect Period Blood Color?
Besides oxidation, other factors can influence the color of your period blood, including:
- Time of the Period: The beginning and end of your period frequently have darker blood due to slower flow. [1, 5, 9]
- Blood Flow: A heavier flow might mean the blood doesn't have as much time to oxidize and may appear brighter red.
- Individual Variations: The natural color variation of blood can differ from person to person. [7]
In Summary
Dark period blood, often brown or even black, is frequently a consequence of oxidized blood and is usually nothing to worry about, particularly if it occurs at the beginning or end of your period. However, always consult a doctor if you have concerns or notice unexpected changes in your menstrual blood color or other symptoms. [4, 7]
