(HealthDay News) -- A bruise occurs when an impact or injury causes blood to pool in tissue beneath the skin.

If you have a bruise, the U.S. National Library of Medicine recommends avoiding activities that could aggravate the area.

You should never try draining the bruise with a needle, and should be aware of extreme pain, swelling, or pressure that doesn't go away. These may indicate a serious condition that requires immediate medical attention.

You should also contact your doctor if you tend to bruise very frequently or easily, or if there are signs of infection -- including redness, discharge, or fever.