Bruises, or ecchymoses, commonly refer to bleeding that is confined within a tissue of the body. Healthy people will develop bruising from blunt injury or with sprains and strains. In some cases, individuals may just have naturally fragile blood vessels which cause them to bruise easily. However, there are also a number of diseases that cause excessive bruising.

Bruised tissue changes colors as it resolves and is reabsorbed. Initially dark red or purple, it fades through green to orange and then yellow. Sometimes bleeding that happens in one place will appear in another. For instance, retroperitoneal bleeding (into the back of the abdomen) will eventually appear in the groin, and bleeding into the thigh or knee will work its way down to the ankle.

An abnormal tendency to bruise can be due to hereditary bleeding disorders like hemophilia, to drugs like coumadin, to diseases of the blood-forming organs like leukemia, or to diseases that increase the fragility of blood vessels. When large bruises develop from minor injuries or reoccur frequently in the same place, they may indicate one of these problems. Easy or unusual brusing should be evaluated by a physician to determine the cause.

A bruise by itself needs no treatment. Ice (ideally a bag with ice and water in it) during the first several hours will reduce the amount of bleeding. Rest, elevation of the injured body part, and applying pressure to the bruised area with an elastic bandage will also slow the accumulation of blood. Twenty-four hours after acquiring the bruise, heat, especially moist heat, will promote healing of the injured tissues.

Eating green, leafy vegetables, a principle dietary source of Vitamin K, may help reduce bruising. Infants receive an injection of Vitamin K at birth to prevent their tendency to develop this deficiency at about two weeks of age. Orange-colored and dark-colored bioflavanoids, from fruits and vegetables (especially blueberries and cherries) can assist in strengthening the connective tissue, slowing the spread of bleeding within the tissue. Arnica, a homeopathic remedy, can be used in case of trauma to lessen bruising. Any astringent herb applied to the skin (such as witch hazel) will tighten the tissue, decreasing bruising.

On rare occasions, a bruise is so large the body cannot completely absorb it. It then turns into a lake of old blood that must be surgically removed. Even more rarely, the lake may become subsequently infected and turn into an abscess.