Medically Reviewed by Gabriela Pichardo, MD on April 15, 2020

What Is a Bruise?

It happens every so often. You notice a purplish mark and think to yourself, “Where did that come from?” Bruises are common. When you bump into something, like your bed or couch, you may injure tiny blood vessels. Blood may pool under your skin and leave the telltale mark. And if you bruise easily, there are many reasons that could explain it.

Age

You may notice more bruises as you age. You slowly lose the fatty layer underneath your skin. Your blood vessels weaken and can be injured easily. That means you have less protection to soften a bump against a table or chair.

Medications

Certain medications -- like aspirin, ibuprofen, and blood thinners -- may get in the way of your body’s ability to form a clot. Some antibiotics may also leave you prone to bruising. Other medications like steroids can make your skin thinner and more fragile. This can also lead to more bruises. Talk to your doctor if you notice more black-and-blue marks.

Family History

Just like dimples, freckles, and curly hair that run in the family, whether or not you bruise easily can, too. Women also tend to have more delicate blood vessels, especially on the upper arms and thigh. Thin or weak blood vessels can be easily injured and leave a purple mark.

Too Much Sun

Sunburn, peeling skin, and skin cancer risk aren’t the only hazards of too much sun. You may also find purple blotches on the back of your hands or arms. Years and years of sunning yourself can weaken the walls of your blood vessels. This can make them vulnerable to damage that leads to bruises.

Dietary Supplements

Easy bruising can be a side effect of some over-the-counter dietary supplements such as ginkgo, ginseng, and garlic. They can thin your blood and make it harder for blood to clot after you knock into something.

Low on Vitamin C

This essential vitamin helps make collagen, an important protein that keeps your blood vessels healthy. If you don’t get enough vitamin C in your diet, you may notice that you bruise easily. While it’s uncommon to have low levels of vitamin C, it’s more likely if you smoke.

Extreme Exercise

You know that physical activity is important for your health. But an intense session may leave you with more than just sore muscles. You may get tiny tears in your blood vessels when you push yourself physically or play contact sports. That can lead to bleeding underneath the skin. You should still be active, but don’t overdo it.

Diabetes

You probably know that diabetes is a condition where your blood glucose levels are too high. Over time, uncontrolled high blood sugar can also damage your blood vessels. This can make you more prone to bruises. And they may linger longer, too.

Vitamin K Deficiency

Vitamin K may not get as much attention as some other vitamins. But it plays an important role in blood clotting. If you don’t get enough vitamin K, you could get more bruises. Still, most healthy adults get enough of this vitamin from foods like leafy green vegetables.

Blood Disorders

In some cases, unexplained bruises may be a sign that your blood cannot do its job well. For example, if you have a condition like hemophilia, you don’t make enough proteins that help your blood clot. Without these proteins, you may bruise easily. But these conditions aren’t common and often come with other symptoms like fever, chills, and weakness.

Drinking Too Much

A drink or two won’t necessarily lead to unexplained black-and-blue marks. But if you drink often and notice frequent bruises, it may be a sign of that your liver isn’t doing its job as well as normal. If your liver is damaged, it doesn’t make enough proteins to help your blood clot. That can account for the bruises.

Cancer

This isn’t a likely reason for bruising. But in rare cases, red or purple bruises could be sign of cancer like leukemia. With leukemia, your body makes a lot of white blood cells. These cells start to crowd out other blood cells. That can make it hard for your blood to do its job and may lead to bruises.

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