Brown menstrual flow that occurs towards the end of a woman's menstrual cycle is normal, according to WebMD. The brown color means that it is old blood coming from the womb lining. During the menstrual cycle, it is common for there to be changes in the color of the blood and its consistency.
The menstrual cycle can last from 2 to 7 days. During that time, the blood color can change from bright red to dark brown, which is normal. The consistency of the blood can also vary throughout the cycle. At the beginning of the cycle, blood flow can be thicker, heavier and contain some clots. A reason for concern is when there are many large clots or regular heavy periods, which is when a physician should be consulted, states WebMD.