Bruises occur when some type of trauma or injury crushes tiny blood vessels (known as capillaries), but doesn't break the skin. They usually take about two weeks to heal, but some bruises can last months. AdvertisementEnd of the Rainbow\"Right after the injury, bruises are usually red or purple as it's the color of the blood that has pooled underneath the skin,\" Mysore says. \"As the bruise heals, the body breaks down the blood that has accumulated under the skin from the broken vessels. Vitamin C is also important to protect your blood vessels.