Bruising is normal and grows more common and more visible as people age. But some bruises can be a warning sign of a serious health issue, doctors caution, especially when they appear suddenly without any apparent causes and are accompanied by symptoms like fatigue, dizziness, or severe pains.

How to differentiate between a normal bruise and a potential warning sign?

Telling a normal bruise from a suspicious one can be challenging without a proper medical evaluation. In general, here’s when a bruise is potentially not innocent and you should see a doctor about it:

  1. If your bruise is unnaturally large: Normal bruises are typically small and localized, often resulting from minor injuries or trauma. They usually start off as reddish or purplish and gradually change color as they heal. If a bruise is unusually large, extends over a large area, or rapidly increases in size, it may warrant medical attention.
  2. If you don’t remember injuring yourself: Normal bruises are often the result of a clear identifiable cause, such as bumping into something, a sports-related injury, or accidental trauma. Random bruising without any recollection of injury or trauma may be a reason for concern.
  3. If the bruise is unusually painful: Bruises can be associated with some discomfort, especially when touched or pressed. However, if the pain is severe, persistent, or worsens over time, it may indicate an underlying issue and should be evaluated by a healthcare professional.
  4. If your bruise doesn’t get better with time: Bruises typically follow a consistent healing pattern and gradually fade away within a couple of weeks. If a bruise persists for an unusually long time, doesn’t show signs of improvement, or gets worse, it may require medical attention.
  5. Additional symptoms like bleeding, dizziness, weight loss, and pains: Pay attention to any accompanying symptoms, such as excessive bleeding, unexplained fatigue, weight loss, or other concerning changes in your health. With any of those symptoms, it is recommended to see a medical professional.

Unexplained bruises can be nothing to worry about — especially bruises on the arms and legs since many people knock into things without remembering they’ve done it. But unexplained bruises on the abdomen, back, or face are more likely to signal an underlying condition.

“If your symptoms arise out of the blue, as in, you never had issues before, and then suddenly you start bleeding easily, it’s important to see a doctor immediately,” said Dr. Tania Elliott, a clinical instructor of medicine at NYU Langone Health in New York.

Sometimes, a bruise may be an external sign of internal bleeding. For example, in the lower left side of the stomach, internal bleeding can be caused by conditions such as a ruptured or bleeding organ, gastrointestinal bleeding, or a ruptured blood vessel. These conditions may require immediate medical attention, especially if you experience severe pain, dizziness, weakness, or other concerning symptoms, so do not hesitate to see a doctor.

Why do people bruise?

More often than not, bruising comes from physical impact or injury. Intense or repetitive physical activity, like running or weightlifting, can also sometimes result in unexplained bruising on legs, or arms, especially if you’re not accustomed to such activities.

When small blood vessels or capillaries are damaged, the leaking blood pools under the skin to form a bruise. As the body reabsorbs the blood, the bruise disappears.

Bruises start out blue or purple, as the blood loses oxygen, and they turn yellow or green from compounds called biliverdin and bilirubin that the body produces when it breaks down hemoglobin.

Older people bruise more easily, as aging skin becomes thinner and loses some of the protective fatty layer underneath that helps cushion blood vessels from injury. Even minor trauma or pressure on the skin can cause bruising in older individuals.

Blood vessels also lose some elasticity over time, while skin damage from sun exposure can cause blood vessels to break easily as well. Apart from that, fluctuations in hormone levels, such as those experienced during menopause, can affect blood vessels and contribute to bruising.

Older people bruise more easily, as aging skin becomes thinner and loses some of the protective fatty layer underneath.

What causes easy bruising other that a severe injury?

If you notice that you bruise easily without any apparent traumas, it might be worth looking into some less obvious causes of bruising.

Your medications can be to blame

Some bruising can be traced to certain medications people take every day. Over-the-counter anti-inflammatories such as ibuprofen and naproxen affect the blood’s ability to congeal or coagulate.

Taking aspirin regularly — which some people do to lower the risk of heart attack or stroke — can lead to bruising as well.

Blood thinners prescribed to lower the chances of developing blood clots can cause black-and-blue marks, as can clopidogrel, a drug some seniors take to help prevent heart disease and strokes.

Steroids such as prednisone and hydrocortisone, which might be prescribed to treat allergies, asthma, or eczema, thin out the skin and can lead to easy bruising.

Antidepressants also can lower the blood platelet count, leaving fewer cells for clotting purposes.

If you’re taking any medications, review the side effects or consult your healthcare provider to see if bruising is a possible concern.

You might be lacking vitamins

Certain vitamin deficiencies, such as a lack of vitamin K, can be an explanation.

A deficiency of vitamin K, found in green leafy vegetables, could indicate a more serious issue such as inflammatory bowel disease or celiac disease.

Deficiencies of vitamins B12 or C or of folic acid also can affect bruising.

Certain vitamin deficiencies, such as a lack of vitamin K, can be an explanation.

Someone lacking in iron, needed to make the hemoglobin for blood to carry oxygen throughout the body, might bruise easily.

Symptoms of iron-deficiency anemia also include severe fatigue, dizziness, or shortness of breath.

Taking dietary supplements like fish oil, garlic, ginkgo, and vitamin E also blocks platelets in the blood from clotting and can lead to easy bruising.

Liver disease

More seriously, a liver disease called cirrhosis can trigger bruising. The liver produces factors needed for blood clotting.

“Any problems with the liver can mess with proteins necessary for clotting,” said Dr. Neha Vyas, a family medicine physician at Ohio’s Cleveland Clinic.

Kidney disease

Kidney disease, too, affects platelets and therefore clotting. Platelets are blood cells that play a crucial role in blood clotting so when there are fewer platelets, it can increase the risk of bruising and bleeding.

While the kidney disease itself may not directly cause unexpected bruising, certain assosiated complications like impaired kidney function can. Additionally, kidney disease can lead to changes in blood vessels, making them more prone to damage and bruising. High blood pressure, a common complication of kidney disease, can also contribute to the weakening of blood vessels.

Lupus

Lupus is an autoimmune disease where the immune system attacks healthy tissues, leading to inflammation and damage in various parts of the body. In some cases, lupus can affect the blood vessels, causing vasculitis. Vasculitis can result in weakened blood vessels, making them more prone to rupture and bruising.

Additionally, lupus can cause a decrease in platelet count or lead to other blood clotting abnormalities, increasing the risk of bruising and bleeding, especially from the nose or gums.

Hereditary bleeding disorders

Hereditary bleeding disorders such as hemophilia A (factor VIII deficiency), hemophilia B (factor IX deficiency), and von Willebrand disease. While it is rare to have any kind of bleeding disorder, it causes bruising and even unexpected bleeding due to the body’s inability to properly form blood clots.

Cancer

Cancers such as Hodgkin’s disease, leukemia, or multiple myeloma. For example, leukemia is known to cause a condition called thrombocytopenia in which people have low blood platelet counts so blood clots cannot form. The danger of the condition is that it can cause internal bleeding.

Vasculitis

Vasculitis is an inflammation of blood vessels, which can weaken them and make them more prone to rupture. This can lead to the development of bruises on the stomach or other parts of the body.

Alcohol

Alcohol causes blood vessels to relax and expand, making them more prone to breaking. Heavy drinking will lead to bruising as well since alcohol intoxication can impair coordination and judgment, increasing the risk of accidents, falls, and injuries that may result in bruising.

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Article is updated on February 26, 2024.