What causes bruises to shift in color as they heal?

Bruises can either be awkward reminders of clumsy accidents or symbols of personal pride. Regardless of how you view them, their intriguing range of colors on the skin makes them worth learning more about. Everyone has had their share of these painful, odd marks at one point or another.

A bruise, or contusion, is a skin discoloration caused by blood trapped beneath the surface. This happens when trauma or injury crushes capillaries (tiny blood vessels), but without breaking the skin. The damaged capillaries leak red blood cells, which accumulate under the skin, forming the familiar blue, purple, red, or black marks.

"A bruise is a patch of discolored skin caused by ruptured blood vessels beneath the surface due to impact or trauma," explains Dr. Navya Mysore, a primary care provider based in New York City.

When a bruise first appears, it can be sore and swollen. Generally, bruises heal within two weeks, though some can persist for months. As the body reabsorbs the trapped blood, the color of the bruise changes, fading from dark shades to lighter ones, often showing a range of striking hues.

End of the Rainbow

"Immediately after an injury, bruises are typically red or purple due to the blood pooling underneath the skin," says Mysore. "As the body breaks down the accumulated blood from the damaged vessels, the bruise undergoes a color shift, changing from black and blue to green and yellow as it heals."

To explain further: when a bruise first forms, it appears red, reflecting the fresh blood just below the skin. Over the next couple of days, hemoglobin—the protein responsible for transporting oxygen—gives the bruise its blue, purple, or black hues. This happens because the oxygen is lost as the hemoglobin breaks down, causing the blood's color to darken and shift.

As a few more days pass, the bruise typically shifts to green or yellow, sometimes even showing hints of brown before completely fading away. This color change happens as the body recycles the iron from hemoglobin to create new red blood cells. The leftover hemoglobin breaks down into a green pigment called biliverdin, which then transforms into bilirubin, a yellow or light brown compound. As these byproducts are either absorbed or eliminated, the bruise gradually fades and disappears.

Who's a Bruiser?

Pretty much everyone gets bruises, but some people are more susceptible than others. For example, elderly individuals are more prone to bruising because of thinner skin and more delicate tissue. Other factors, such as specific medical conditions, illnesses, and medications, can also heighten one's tendency to bruise.

So, what do you do when you get a bruise, a black eye, or any other type of contusion? Typically, time is the best healer.

"Generally, minor bruises heal within a week," says Mysore. "Moderate to severe bruises can take anywhere from two weeks to a month to fully heal. If the injury is severe enough, it could lead to a hematoma, a painful collection of clotted blood within the tissues, which might take several months to resolve—but it will eventually clear up on its own."

While there are many myths and quick-fix tales about how to instantly get rid of bruises, the most effective remedy is simple: rest and ice. "After an injury, rest the affected area as much as possible and apply ice right away," advises Mysore. If that doesn't seem to speed up the healing, you can try using heat to boost circulation and help the healing process along.