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Why Do Bruises Change Color?

Published in Bruise Healing 2 mins read

Bruises change color due to the breakdown of blood under the skin after an injury. Here's a breakdown of the process:

The Science Behind Bruise Color Change

When you get a bruise, it’s actually blood that has leaked out of damaged blood vessels and settled under the skin. The color changes you observe are due to the hemoglobin, which carries oxygen in the blood, changing its chemical structure.

The Color Progression of a Bruise

Stage Timeframe Color Cause
Initial 0-1 days Red Fresh blood is released from damaged blood vessels.
Early 1-2 days Bluish-Purple/Black Hemoglobin in the blood begins to break down. The chemical structure of hemoglobin changes, causing the red color to change to bluish-purple or even black.
Later 5-10 days Green/Yellow Further breakdown of hemoglobin turns the bruise to green and then yellow.

Detailed Explanation

  • Red: Initially, the bruise is red because you are seeing the blood that has just leaked out from the damaged blood vessels under the skin.
  • Bluish-Purple/Black: Within a day or two, hemoglobin, an iron-containing substance responsible for carrying oxygen in the blood, starts to degrade. This chemical change causes the bruise to shift to a bluish-purple or even black color.
  • Green/Yellow: Over the next several days, the body continues to break down the blood. The breakdown products of hemoglobin result in the bruise turning green and then yellow as it gradually heals.

Why Does This Happen?

The changing colors are a natural part of the healing process. The body is working to clear away the leaked blood and repair the damaged tissue. Each color indicates a different stage of the breakdown of hemoglobin. This progression of color changes helps doctors estimate how old a bruise might be.

Important Note

While most bruises heal without any complications, very large or particularly painful bruises should be evaluated by a doctor.