Why Bruises Form and How They Heal

Like we mentioned before, bruising appears when tiny blood vessel, or capillaries, break due to a blow to the skin. The appearance of a bruise changes over time, and you can tell how old a bruise is and where it is in the process of healing by observing its color. Generally, your skin should look normal again in about two to three weeks after an injury.

  • When a bruise is brand new, it will appear reddish due to the color of the blood that leaked from the capillaries under the skin.
  • At one to two days old, a bruise will take on a bluish or purple color. The swelling at the site of the bruise will cause oxygen to be cut off, and hemoglobin, the substance that carries iron in your blood, will turn blue.
  • At six days old, a bruise will turn a greenish color as the hemoglobin breaks down and the area begins to heal itself.
  • At eight to nine days old, a bruise will then turn yellow or brown. This is the final stage in the body's re-absorption of the blood.

But what do you do if your bruise doesn't change color or heal properly? If the bruise remains firm and gets bigger or more painful, a hematoma may have formed. This happens when blood collects under the skin or in the muscle, and instead of trying to fix this, your body walls the blood off. If this happens, you need to have the hematoma drained by a doctor.

A less common reason for a bruise to stick around is that your body has deposited calcium around the area of your injury. This is called heterotopic ossification and it causes the area of your bruise to become firm and tender. You doctor will be able to identify a heterotopic ossification through X-ray.

In general, bruises at their worst are momentarily painful and an eyesore for a week or two. But sometimes bruising can indicate dangerous medical conditions. Read on to learn when you should worry about a bruise.