Bruises often change colors as they heal. Bruises typically turn yellow or green roughly five to 10 days after your injury and do so because the body produces specific compounds to break down the blood that has gathered in the area. These compounds are known as biliverdin and bilirubin and are actually pigments that occur naturally when they break down blood. When the bruise turns yellow, it’s because more bilirubin is responsible for breaking down the blood and when it turns green, it is the action of biliverdin.