A green bruise is the color of a contusion as it heals, the University of Rochester Medical Center explains. A bruise changes color as it heals and disappears. Typically, the progression of color change starts from a reddish blush, then a slowly darkening blue or purple, followed by green and a yellow-brown color.
According to the NHS, a bruise is simply a type of bleeding that occurs beneath the skin. It occurs because of trauma to the body that causes blood vessels to break and changes color as days pass by, mainly because white blood cells gradually remove the decayed blood products. The NHS notes that because different components of the blood have various colors, bruises changes in appearance as they reflect the blood’s color. A green bruise shows up due to the green pigment biliverdin.
Dr. William C. Shiel Jr. states in an article on MedicineNet that it is possible to tell how old a bruise is by looking at it. The first appearance of a bruise shows a reddish looking skin. By one to two days, it appears blue or purple. After six days, the color starts to change into green and by eight to nine days, a bruise will look yellowish-brown. Generally, the bruised region returns back to normal within two to three weeks.
The NHS suggests treating bruises by limiting the bleeding. This is done using cold compress to cool the area.