why is my period blood black and thick

Black and thick period blood is typically caused by older blood that has taken longer to exit the uterus and has oxidized, which darkens the blood's color. The thickness can be due to clot formation during slower menstrual flow or heavier bleeding. This is usually a normal part of the menstrual cycle, commonly occurring at the start or end of a period when the flow is slower, allowing the blood to darken and thicken naturally. However, black and thick blood can sometimes indicate hormonal fluctuations, conditions like polycystic ovary syndrome (PCOS), or underlying issues such as fibroids, endometriosis, or infections. Dehydration may also contribute to thicker menstrual blood. If the black blood is accompanied by symptoms like severe pain, foul odor, heavy or prolonged bleeding, or other unusual signs, it is advisable to consult a healthcare professional for evaluation. In summary, black and thick period blood is mostly due to older, oxidized blood and slower flow but should be monitored if accompanied by concerning symptoms.