Why Do Bruises Change Colors?
Have you ever wondered why your bruises change color, or if those colors signify something? Bruises, also known as hematomas, get their signature dark purple-bluish color from the presence of blood under the skin. Injury to the site where the bruise forms causes red blood cells to break down, and with each new stage of breakdown comes a slightly different bruise color.
Though the red blood cells undergo breakdown, the area itself under the site of injury is going through a process of healing. When you see your bruise start to change colors, rest assured that your body is performing the appropriate processes to heal your wound.
What Is a Bruise?
A bruise develops at the site of an injury on the skin, typically when some sort of trauma causes bleeding under the surface of the skin without actually breaking the surface. With minor injuries, such as bumping your arm or pinching your finger, the bleeding is usually confined to your skin. The bruise will likely appear within minutes to hours.
With more forceful trauma, such as twisting your ankle, running into the corner of a table or getting hit with a baseball, bleeding typically occurs in the deeper tissues of your body. The blood then gradually seeps into your skin over a period of hours to days. This is why you might not see a bruise for a day or two after you’ve had a fall or other injury.
The size of a bruise depends on what caused your injury and the amount of force involved in creating it. The more forceful the injury is, the greater the amount of bleeding and the larger your bruise will be. The closer to your skin’s surface the bruise is, the more intense the colors of the bruise will likely be, too.
What Are the Early Colors of Bruises?
Fresh bruises can develop anywhere from minutes to days after an injury, depending on how deep below your skin’s surface the bleeding is. Typically, a new bruise progresses from red to blue to purple within the first few days after an injury.
Red Bruises: When you first get a bruise — especially one near the surface of your skin — it usually appears red. The color comes from fresh blood leaking into your tissues. Fresh blood is bright red because it contains a protein called hemoglobin, which carries oxygen from your lungs to other parts of your body.
Blue Bruises: Within a few hours, blood that has leaked from your injured blood vessels loses the oxygen it was carrying. As this occurs, the blood becomes darker and the bruise begins to look more bluish or purple.
Purple Bruises: Typically, over one to three days (depending on the severity of your injury), a bruise becomes more intensely purple and may even appear black. This occurs as red blood cells break down and iron is released into the injured area.
Note that, if you have a deep bruise, the red stage may have already passed by the time you’re first able to see the bruise. In this case, the first color you see may be blue or purple.
Do Bruises Change Color as They Heal?
As mentioned, when red blood cells break down, they release an iron-rich protein called hemoglobin. While your bruise begins to heal, your body converts the hemoglobin into other pigmented proteins. The presence of these proteins causes your bruise to change color as it heals.
Green Bruises: A green bruise indicates that the site of injury has entered its final stages of healing. The bruise may transition from purple to green at the edges or center of the injury site. The green color is due to the presence of a hemoglobin breakdown product called biliverdin. The last part of the word, "verdin," comes from the Latin word for "green."
Yellow Bruises: The final step of healing involves the bruise turning a yellowish color. This is from the final breakdown product of hemoglobin appearing in your skin; it’s known as bilirubin. As your body clears the remaining cellular and other debris from the bruised area, the yellow pigment fades and your skin returns to its original tone.
You may have noticed that many bruises tend to be multicolored. This is because the amounts of blood in different areas of the bruise vary, so the stages of healing overlap.
How Should You Care for a Bruise?
There are a few things you can do to limit the extent of a bruise and help it heal quickly. The most commonly suggested technique involves a process known as RICE, which stands for "rest, ice, compress and elevate":
- Rest. Once you notice your injury, try to rest the affected area. For example, if you’ve sustained a blow to your elbow, try not to use that arm when possible.
- Ice. Wrap an ice pack or a bag of frozen vegetables in a clean towel prior to applying it to the affected area to minimize skin irritation. Do not leave the ice pack on for longer than 20 minutes at a time. You can repeat your icing sessions throughout the day to help prevent swelling.
- Compress. Compression of the area can help reduce swelling and limit the amount of bleeding under your skin. This can lessen the severity of your developing bruise. Compression involves applying slight pressure without cutting off circulation or blood flow.
- Elevate. If possible, keep the injured area above the level of your heart to minimize swelling.
You should see a healthcare professional if any of the following apply to you:
- You seem to find bruises all over your body and cannot account for injuries that would’ve caused them.
- You’ve sustained trauma to your face (particularly in the case of a black eye).
- Your bruise continues to become larger or stays painful even after following the RICE method for three days.
- You have a family history of bleeding or clotting disorders.
- You cannot functionally use the area affected by the bruise, such as not being able to walk on a bruised ankle.
Though bruises can be painful, they’re signs of healing and indicate your body is working hard to mend your injury. The next time you get a bruise, you’ll know how to interpret the changing colors of your injury and can tell exactly where you are in the healing process.
Medical content reviewed by Dr Samantha Miller, MBChB