You accidentally walk into the corner of your coffee table and the next day there's a huge bruise on your leg. Or maybe bruises show up and you don't even remember hurting yourself. Bruising with the slightest bump doesn't mean you have a serious health problem, especially if your bruises tend to be small and don't show up often.
A bruise develops when small blood vessels under the skin tear or rupture. Blood leaks into tissues under the skin and causes the oh-so-attractive black and blue color. They can also become bumpy, which is called hematoma, which happens when blood collects and pools under the skin. As bruises heal (usually within two-four weeks) they often turn all colors of the rainbow, including purplish-black, reddish-blue, or yellowish-green. Sometimes the area of the bruise even spreads down the body in the direction of gravity. A bruise on a leg usually will take longer to heal than a bruise on the face or arms.
A tendency to bruise easily sometimes runs in the family, so you might have inherited this trait from one of your parents. Women bruise more easily than men, especially from minor injuries on the thighs, upper arms, and butt. The amount of fat covering your body may also play a part — if you don't have much, there's less cushioning protection, so bruises will appear with the slightest knock. If you notice more bruises now than you did several years ago, it could be due to all those hours spent outside without sunblock, as sun-damaged skin causes blood vessels to break more easily.
Sudden unexplained bruises, bruising that happens frequently, or bruises that don't go away after a month, could be a sign of a health issue, such as an infection or a vitamin deficiency of B12, C, or folic acid [2], so if you're concerned about it, it's best to make an appointment with your doctor.