What it means if you bruise easily and when to see a doctor

Your skin reveals many clues about your health, so a tendency to bruise easily can be worrisome.

You may feel like the main character in Hans Christian Andersen's fairy tale "The Princess and the Pea," in which the delicate princess wakes up “black and blue all over” after sleeping on a single pea covered by a tower of mattresses and feather beds.

Doctors say most cases are nothing to worry about, but bruises can sometimes signal certain problems.

Dr. Monique Tello, a primary care physician at Massachusetts General Hospital, encounters patients with “easy bruising anxiety” quite frequently.

“Thus far in my ten years as an attending (physician), no one in my primary care practice has had any serious underlying condition,” Tello told TODAY. “Usually, they didn’t remember some bump, or were taking aspirin. Rarely, bruising can be a clue that there is a medical issue.”

Most bruises happen when you suffer an injury that fails to break the skin, but crushes the small blood vessels underneath. Blood then leaks and becomes trapped under the surface, leaving the telltale mark.

If you work out a lot, you might notice bruising in fatty areas that are exposed, like your thighs, buttocks or legs, said Dr. Abigail Waldman, a dermatologist at Brigham and Women’s Hospital.

Here are other possible causes of easy bruising:

BLOOD THINNERS
Besides injury, blood thinners — medicines that slow down or decrease your blood's clotting ability — may be the No. 1 cause for easy bruising, Waldman said. They’re very common, ranging from aspirin to drugs like Coumadin. You might not even realize you’re taking one: Fish oil supplements, ginkgo biloba, alcohol and garlic have similar effects. If you’re on blood thinners, it may take longer for bleeding to stop, leading to bigger bruises.

OTHER DRUGS
Steroids can lead to thinner skin, so you may notice bruising with just slight trauma. Chemotherapy can lower the number of platelets — the cells that help your blood to clot — in your body, the National Cancer Institute notes. A low platelet count means a higher risk of bruising.

AGING
As you age, your blood vessels become more fragile. “You can think of it like a hose that holds the blood,” Waldman said. “As you get older, you sort of have some leaks in the hose. So very small injuries can cause that area to open up and leak blood out into the skin, causing a bruise.”

Older skin is more fragile, too, and there’s less fat underneath it, leaving you with less cushion if you bump into something. All of those factors can lead to senile purpura, or bruises that show up after very slight injury in elderly people. The marks typically appear in areas that have had significant sun exposure, like the arms and the hands, Waldman said

“Unfortunately, there’s not a lot you can do to prevent it, except to try to avoid any even minimal injury. But sometimes it’s nice for patients just to have a diagnosis,” she added.

VITAMIN DEFICIENCY
Easy bruising might suggest you lack enough vitamin K, found in leafy green vegetables, broccoli, and Brussels sprouts. Most people get enough of this fat-soluble vitamin in their diets, so you don’t need to take a supplement, Waldman said. But if you are deficient, it’s a sign you may not absorbing vitamins correctly, she added. That may include people with Crohn’s disease or ulcerative colitis.

A severe lack of vitamin C — or scurvy — could also be the culprit because the vitamin is involved in building the walls of blood vessels, Waldman said. Scurvy is rare in the U.S. — symptoms include bleeding around hair follicles and bleeding gums.

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