Up to 55 percent of healthy people report they seem to bruise easily, but there is usually a simple explanation of why it happens.
Bruising occurs when blood vessels leak under the skin. The pool of blood forms a red, and eventually blue, mark on the skin. The body gradually reabsorbs the pooled blood.
The most obvious cause of bruising is an injury. You might get bruising from sports, exercise, or just your normal work when you run into things or other people.
Increased bruising is normal with age. Skin becomes thinner, and begins to lose elasticity. Older people may also lose the fat under the skin that cushions blood vessels, according to Health.com.
Medication can increase bruising. Drugs, such as aspirin or ibuprofen can block the normal function of platelets, the part of the blood that binds to clotting factors. A blood thinner like Warfarin causes bruising. Steroids taken for breathing problems, even if inhaled, can cause skin thinning, leading to bruising.
Sun damaged skin can result in weakened blood vessel walls and cause purple patches on the backs of hands and forearms.
Finally, there are some rare disorders that cause abnormal bleeding including low blood platelet count, bleeding disorders, and blood cancers. Less rare is liver damage (because of Hepatitis C or alcohol use).
