A bruise or “contusion” appears on the skin when it has suffered trauma such as a cut or a blow to the area. The injury causes tiny blood vessels called capillaries to burst, and the blood gets trapped below the skin’s surface.
Bruises can occur on the body at any age. Some bruises appear with very little pain to the area, so they can go unnoticed. As you age, your skin becomes thinner, and the capillaries under your skin become more prone to breaking. This causes older people to bruise easier than younger people.
Certain medications also make it more likely for you to bruise; this is especially the case with blood thinners. You may also notice bruising after receiving an injection or wearing tight clothing.
Some people bruise easily, with little impact to their body; in most cases, this is nothing to be alarmed about. However, if this is a recent development, speak to your physician about potential causes and treatment options.
There are three forms of bruising:
- Subcutaneous bruises occur just beneath the skin.
- Intramuscular bruises occur in underlying muscle.
- Periosteal bruises are on the bones.
Symptoms of a bruise vary depending on the cause of the bruise. They may include:
- Discoloration of the skin in the area of bruising. The discoloration may be blue, red, greenish or purple.
- Tenderness in the area of bruising. The tenderness will improve as the bruise heals.
Seek medical attention if you have:
- bruising while taking a blood thinner mediation
- swelling and pain in the area of bruising
- bruising that occurs after a hard blow or fall
- bruising that occurs along with a suspected broken bone
- bruising for no reason
- bruising that fails to heal after four weeks
- bruising under the nails that is painful
- bruising accompanied by bleeding from the gums, nose, or mouth or blood in your urine, stool, or eyes
Also, see a physician if you have unexplained bruising, bruises that are not painful, bruises that reappear in the same area without injury, or any black bruises on your legs. Blue bruises on your legs may come from varicose veins, but black bruises can indicate deep vein thrombosis, which is the development of a blood clot. This can be life threatening.
Unexplained bruises that appear on the shin or knee may come from bumping the area on a doorframe, bed frame, post, or chair without noticing.
Other common causes of bruises include:
- sports injuries
- car accidents
- blows (such as someone hitting you or being hit by a ball)
- medication side effects (you are more susceptible to bruising if you are taking aspirin or warfarin)
Bruises that develop after suffering a cut, burn, fall, or injury are normal. It is not uncommon to develop a knot in the area of bruising. These bruises form as part of your body’s natural healing process. In most cases, they are nothing to worry about. However, if you have a wound that bruised then reopened and produced pus, clear liquid, or blood, see a physician promptly as these are signs of infection.
If a child has unexplained bruising, take him to a physician to determine a cause. In some cases, unexplained bruising on a child could be a sign of abuse.
Bruises may be treated at home using the following options:
- Use an ice pack to reduce swelling. Wrap it in cloth to avoid putting the pack directly on your bruised skin. Leave the ice on your bruise for 15 minutes every hour.
- Rest the area of bruising.
- If practical, raise the bruised area above your heart to keep blood from settling into the bruised tissue.
- Take an over-the-counter medication (such as acetaminophen) to reduce pain in the area.
Prevent bruising by being cautious when climbing, playing, exercising, and driving. Use pads on your knees, elbows, and shins when cleaning or playing sports to avoid bruising in these areas. Reduce the risk of getting bruised when playing sports by wearing shin guards, shoulder pads, hip guards, or thigh pads.