What Do Bruises Tell the Human Body?

Mainly, ouch! A bruise is a sign to your body that you injured it. Most bruises (banging your shin on the coffee table, stubbing your toe, knocking into a doorknob) are minor injuries that you can treat fast and easily.

What Is a Bruise?

A bruise results from an injury that made the small blood vessels under your skin bleed. Because the skin isn't broken, there's nowhere for this blood to go other than under your skin, so it pools and clots there. This is why the color of your skin changes- your skin is the same; it's just showing the injury beneath.

Why Did My Bruise Change Colours?

Bruises change colors as part of the healing process. Depending on how severe the injury that caused the bruise was (how hard you bumped yourself to generate the bruise), your bruise can be a variety of different colors, but the process is usually similar to:


  • Red- Fresh blood has just pooled under the skin
  • Purple, Blue, or Black- Taking anywhere from a few minutes (for particularly nasty bumps) to 2 days, the blood under the skin has lost oxygen
  • Yellow or Green- In 5-10 days, the bruise will turn yellow or green. While ugly, this is actually good. This shows that the body is breaking down the hemoglobin in the pooled blood, meaning the bruise will be gone soon.
  • Yellow-Brown or Light Brown- After 10-14 days, that blood will continue to break down, filtering harmlessly back into your bloodstream and fading until you can no longer see it.

Do I Need to See a Doctor?

99 out of 100 times, you'll receive a bruise that you can handle at home. You can minimize bruises by elevating the injury to prevent blood pooling, applying cold (like ice packs) to reduce swelling, and taking an over-the-counter pain reliever (like acetaminophen or ibuprofen) if you need it.


Sometimes though, bruises might need to be seen by a doctor. Consider visiting a health care specialist if the bruise:


  • Is a hematoma. A hematoma is a big collection of blood in the tissue, and more significant injuries usually cause it. Think of a goose egg bulging out of your skin after being hit by a hammer. If it stays the same color, size, and firmness with a consistent level of pain, it might need medical attention to get better and prevent more serious issues
  • Occurs with no known cause on the abdomen, head, or trunk- this might be a sign of problems with your internal organs
  • Causes vision impairment
  • Is on your head or neck
  • Happens alongside a broken bone
  • Causes an arm or leg to go numb or lose function
  • Continues to grow
  • Recurs in the same spot
  • Last longer than two weeks


Bruises Tell Your Body an Injury Has Occurred

When you stumble and land too hard or bang your hand on a passing door jamb, you can cause broken blood vessels to form under the skin. These are signs that you need to be a little more careful and ice the area.