8 Causes of Random Bruising

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Bruises, also referred to as contusions, occur when there is an injury to tissues underneath the skin. This can damage blood vessels and causes blood to pool below the surface of the skin, leaving behind black, blue, purple, brown, green, or yellow marks.

However, bruises aren’t typically something to worry about, and they tend to heal on their own in a few days or weeks.

Random bruising may happen without a clear cause or injury. Some people may be more susceptible to random bruising than others, and depending on the circumstance, you may want to see a healthcare professional. Read on to learn more about unexplained bruising, what causes it, and when to seek medical attention.

Midsection Of Woman With Bruise On Arm

Sharon Mccutcheon/ EyeEm / Getty Images

What Are the Risk Factors for Random Bruising?

There are various risk factors associated with random and easy bruising, such as genetics, age, and sex.

While there's no evidence of a specific genetic component that drives random bruising, studies have shown that people who bruise easily often have close family members who suffer from easy bruising. When a person bruises easily, this can lead to random and unexplained bruises from everyday activities that would typically not cause bruising.

Genetics and Random Bruising

In some people, random bruising may be impacted by their genes simply because of how they are physically built. For example, a person may have fairer skin and more fragile blood vessels, two factors that can make bruises develop more easily and appear darker in color.  

On top of genetics, aging can be a factor of unexplained bruising. Older adults often experience random bruising as part of the natural aging process. This is due to weakening blood vessels that are more prone to breakage even with slight injury to the area. Sex can also affect bruising as women tend to bruise more easily than men.

What Causes Random Bruising?

There are several causes that may lead to unexplained bruising, like certain medications, nutrient deficiencies, and medical conditions.

Medications

Some medications can lead to easy or random bruising because of how they affect the body. Specific medications include:

  • Aspirin
  • Pain management medicines such as ibuprofen or naproxen
  • Blood thinners

Blood Thinners and Random Bruising

Blood thinners are given to people who have issues with blood clotting. Our blood naturally clots to prevent excessive bleeding related to an injury. Blood thinners prevent this clotting, which makes it easier for bruises to develop following minor injuries because of the excessive pooling of blood underneath the skin.

Bleeding Disorders

Bleeding disorders occur when the blood doesn’t clot as it should. There are several different bleeding disorders that can cause a person to bruise randomly, including:

  • Hemophilia A and B: Both Hemophilia A and Hemophilia B occur when the blood doesn’t clot properly. Hemophilia A is a genetic condition, and Hemophilia B develops when a person is missing a specific factor (factor IX) that encourages proper blood clotting.
  • Von Willebrand disease: This is an inherited bleeding disorder that also causes issues with blood clotting.

Nutrient Deficiency

Nutrients are important for all bodily functions, and not getting enough vitamins and minerals can cause various health issues. One health issue that can arise from a lack of nutrients is unexplained bruising. There are several nutrient deficiencies associated with easy or random bruising, including:

  • Vitamin C: Vitamin C is important for many reasons, one being wound healing. Without enough vitamin C in the body, random bruising can occur.
  • Iron: Iron is vital for healthy blood cells. It aids in the delivery of oxygen throughout the body to cells and without adequate oxygen, skin becomes more likely to bruise.
  • Vitamin K: Vitamin K plays a role in blood clotting. Without enough vitamin K, blood clots don’t form as quickly leading to more blood under the skin, and thus, a bruise.

Vitamin C Deficiency and Leg Bruising

Although vitamin deficiencies can lead to random bruising across the entire body, one case report found the bruising to be localized to the legs.

Diabetes

Diabetes is a chronic condition that develops because of the body’s inability to produce or use insulin, a hormone designed to manage blood sugar levels. The condition can lead to bruising that lasts longer than normal because of the way it affects wound healing.

Diabetes and Red Spots on the Skin

Red spots, also called blood spots, can look similar to bruises, although they don’t develop because of an injury. They typically arise due to an underlying health condition such as diabetes. Other common causes of blood spots include low blood platelets, blood clotting disorders, inflammation in the blood vessels, and vitamin C deficiency.  

Low Blood Platelets

Blood platelets are specific cells that exist within the blood. When certain blood vessels are damaged, blood platelets bind together to repair the issue. People with low counts of blood platelets often bruise easily because there are fewer platelets in the blood to repair damaged blood vessels. A low platelet count is also called thrombocytopenia, and there are a few potential causes, such as:

  • Certain cancers including leukemia and spleen cancer
  • Chemotherapy drugs
  • Biological therapies
  • Radiation therapy of the bone marrow or pelvis
  • An enlarged spleen

Cushing's Syndrome  

Cushing's syndrome is a condition that arises when levels of cortisol, a stress hormone, are too high in the blood. The syndrome causes easy bruising because it can lead to thinning skin.

Ehlers-Danlos Syndrome

Ehlers-Danlos syndromes are a group of hereditary health conditions that negatively affect the function and structure of connective tissues such as the skin, joints, and walls of the blood vessels. Because of this, easy bruising is often a symptom of Ehlers-Danlos syndrome.

Non-Hodgkin’s Lymphoma

This is a type of cancer that begins in lymphocyte cells, which are immune cells designed to aid in the fight against pathogens. If a person has non-hodgkin’s lymphoma, especially in their bone marrow, it can reduce blood cell count and blood platelet count leading to clotting issues and random bruising.

What Is the Treatment for Random Bruising?

In many cases, random bruising doesn’t require any treatment at all and will heal on its own. If you are in pain because of the bruise, you can apply a cold compress to the area to slow down blood flow. If you are able to, you can also keep the bruise elevated above the heart to prevent further blood pooling.

Bruises that are caused by underlying health conditions are addressed by treating the specific condition or disease. Therefore, treatment options will vary widely if you are experiencing bruising because of a health condition. 

When to Call a Doctor

Experiencing random bruising can be alarming, but it doesn’t always warrant a visit to your doctor. That being said, you should see your doctor if:

 

  • The bruise doesn’t go away
  • You don’t know where the bruises are coming from and they occur regularly
  • The bruise is exceptionally painful

Can You Prevent Random Bruising?

It’s difficult to avoid bruising completely, especially when the cause is unknown.

People that are active should take special precautions while participating in physical activities to prevent injuries that could lead to bruises. This can be done by wearing protective gear while you play sports or engage in other physical activities that could lead to bruising.

A Word From Verywell

In many cases, unexplained or random bruises aren’t a cause for concern and will likely disappear on their own in a couple of weeks.

If you find yourself constantly bruised up and don’t know why, contact your healthcare provider as you may have an underlying health condition or nutrient deficiency to blame for the constant contusions.

Frequently Asked Questions

  • What is a bone bruise?

    A bone bruise is a type of bruise that occurs when blood and fluid build up inside and around an injured bone. It is a traumatic injury slightly less severe than a bone fracture.

  • Do bug bites leave bruises?

    While not everyone will experience bruising after a bug bite, it is entirely possible that you develop a small contusion if you get bitten by an insect. It is more commonly associated with specific insects.

  • How long does it take for a bruise to heal?

    Bruises typically heal on their own within two weeks of the initial injury. If you find yourself in pain because of the bruise, you can apply a cold compress and keep the bruise elevated above the heart. This may help speed the healing process because it lowers inflammation and prevents more blood from pooling in the area.

  • Why is my bruise yellow or green?

    Bruises often change colors as they heal. Bruises typically turn yellow or green roughly five to 10 days after your injury and do so because the body produces specific compounds to break down the blood that has gathered in the area. These compounds are known as biliverdin and bilirubin and are actually pigments that occur naturally when they break down blood. When the bruise turns yellow, it’s because more bilirubin is responsible for breaking down the blood and when it turns green, it is the action of biliverdin.

  • Why is my bruise hard?

    Bad bruises, also known as hematomas, can occur following a more serious injury. Along with the discoloration associated with a bruise, hematomas can also cause the area to feel hard or firm to the touch.

12 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Angelica Bottaro
Angelica Bottaro is a professional freelance writer with over 5 years of experience. She has been educated in both psychology and journalism, and her dual education has given her the research and writing skills needed to deliver sound and engaging content in the health space.