Black and blue marks are often associated with bruises. A bruise, or “contusion,” appears on the skin due to trauma. Examples of trauma are a cut or a blow to the area. The injury causes tiny blood vessels called capillaries to burst. The blood gets trapped below the skin’s surface, which causes a bruise.
Bruises can occur at any age. Some bruises appear with very little pain, and you might not notice them. While bruises are common, it’s important to know your treatment options and whether your condition warrants emergency medical attention.
What Different Types of Bruises Are There?
There are three types of bruises based on their location on your body:
- Subcutaneous bruises occur just beneath the skin.
- Intramuscular bruises occur in the underlying muscles.
- Periosteal bruises occur on the bones.
What Are the Symptoms and Signs of Bruises?
Symptoms of the bruise vary depending on the cause. Discoloration of the skin is often the first sign. While they’re usually black and blue, bruises can also be:
- yellowish (most often occurs as the bruise heals)
You may also experience pain and tenderness in the area of bruising. These symptoms generally improve as the bruise heals.
Other symptoms indicate a more severe condition. Seek medical attention if you have:
- bruising while taking aspirin or other blood thinners
- 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 your nails that is painful
- bruising accompanied by bleeding from your gums, nose, or mouth
- bruising accompanied by blood in your urine, stool, or eyes
Also, see a doctor if you have:
- unexplained bruising, especially in a recurring pattern
- bruises that aren’t painful
- bruises that reappear in the same area without injury
- 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.
What Causes Bruises?
Unexplained bruises that appear on the shin or knee may come from bumping the area on a doorframe, bed frame, a post, or a 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
- medications that thin the blood, such as aspirin or warfarin (Coumadin)
Bruises that develop after you suffer a cut, burn, fall, or injury are normal. It’s 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’re nothing to worry about. However, if you have a wound that bruises, reopens, and produces pus, clear liquid, or blood, see a doctor promptly. These can be signs of an infection.
If a child has unexplained bruising, take them to a doctor to determine the cause. Unexplained bruising on a child can be a sign of abuse.
Certain medications also make it more likely for you to bruise. This is especially the case with blood thinners and corticosteroids. Fish oil supplements have similar blood-thinning effects and may lead to bruises. You may also notice bruising after receiving an injection or wearing tight clothing. Bruises also tend to be more common in older adults. As you age, your skin becomes thinner, and the capillaries under your skin become more prone to breaking.
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, talk to your doctor about potential causes and treatment options. Women are also more prone to bruising.
How to Treat Bruises
You may treat bruises at home with some of the following options:
- Use an ice pack to reduce swelling. Wrap the pack in cloth to avoid putting it directly on your bruised skin. Leave the ice on your bruise for 15 minutes. Repeat this every hour as needed.
- Rest the bruised area.
- 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 (Tylenol), to reduce pain in the area.
- Wear tops with long sleeves and pants to protect bruises on your arms and legs.
How to Prevent Bruising
You probably won’t go through life without ever getting a bruise, but you can prevent some bruising by being cautious while 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
- thigh pads
Occasional black and blue marks from bruises are a normal occurrence. Bruises can be uncomfortable, but they usually heal on their own unless they are associated with a medical condition. See your doctor if a bruise doesn’t improve or resolve within three weeks.