Bruising occurs when blood becomes trapped under the skin, usually following an impact injury that damages small blood vessels. However, not all bruising has a simple explanation.

Although random or sudden bruising does not necessarily mean that a person has a medical condition, it may still be worth discussing with a doctor.

This article will expand on factors in and causes of random bruising and accompanying symptoms. It also explains bruising in pregnancy and when to see a doctor.

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Random bruising may indicate an underlying health problem.

Most bruises are nothing to worry about and will heal within a couple of weeks. They can vary in color, and skin color may affect the appearance of a bruise.

Learn more about what the colors of a bruise mean here.

Learn more about bruises on dark skin here.

However, random, sporadic bruising may be a symptom of something less obvious, especially if there are other symptoms. Bruises on the torso, back, or face could especially be a concern.

Here are some key factors in random bruising:

  • Age: Older adults are much more susceptible to bruising. The skin becomes thinner and less flexible, especially on the backs of the arms. Blood vessels lose elasticity and break much more easily.
  • Sex: Females tend to bruise more easily than males. Although there is no conclusive medical evidence as to why, females typically have thinner skin, which makes it easier for bruises to develop.
  • Genetics: A tendency to bruise easily can run in the family. For example, von Willebrand’s disease is a hereditary bleeding disorder in which the blood does not clot properly. This leads to easy bruising or larger bruises. However, it only affects around up to 1% of the population of the United States.

Unexplained bruising is very common and heals relatively quickly. However, if a bruise persists, changes in size, or looks unusual, there may be an underlying condition or other factors.

The following are some possible causes of random bruising.

Medications and supplements

Medications such as anticoagulants, nonsteroidal anti-inflammatory drugs, and corticosteroids reduce the blood’s ability to clot. This may result in blood leaking from vessels and accumulating under the skin.

Some studies suggest that certain dietary supplements — such as fish oil, garlic, and ginseng — may also be factors in bleeding and bruising.

Someone who takes medication and has random bruising should speak to a doctor for advice and to discuss their drug and family medical history.

A bleeding or clotting disorder

Underlying bleeding disorders — such as hemophilia, thrombocytopenia, or factor V deficiency — can cause bruising.

Hemophilia is a genetic condition wherein people lack either clotting factor VIII or IX, resulting in excessive bruising. It is a rare condition that mostly affects males.

People with immune thrombocytopenia have a low platelet count, and bruising can also appear for no reason. Platelets are cells that help the blood to clot and stop bleeding.

Factor V deficiency is a rare bleeding disorder wherein people lack the protein coagulation factor V. This prevents the blood from clotting. Symptoms can occur at any age, but most severe cases tend to occur during childhood.

Other common symptoms of a bleeding disorder include:

  • nosebleeds
  • blood in the urine or stool
  • bleeding gums


Sepsis is an infection that causes a buildup of toxins in the blood or tissues. People with sepsis often develop a cluster of tiny blood spots, resembling pinpricks in the skin (petechiae) or purple areas (purpura). Without treatment, these may increase in size, join together, and form larger bruises.

Also known as blood poisoning, sepsis requires immediate emergency treatment.

Vitamin deficiencies

A poor diet can affect health in a number of negative ways, and vitamin deficiencies can contribute to random bruising.

Some deficiencies include vitamin C deficiency and vitamin K deficiency.

Required for collagen production, boosting the immune system, and maintaining antioxidant activity, vitamin C is versatile and vital to health. It also eliminates harmful free radicals that can lead to tissue degeneration and random bruising.

The result of extreme vitamin C deficiency is scurvy, which also leads to bleeding gums, fingernail and tooth loss, and heart failure.

Meanwhile, vitamin K deficiency can contribute to significant bleeding, poor bone development, and cardiovascular disease. It is rare in adults, generally occurring in the neonatal period.

However, taking anticoagulants and antibiotics that interfere with vitamin K production may cause deficiencies.

People can prevent vitamin deficiencies by making dietary changes and taking supplements.

Liver or kidney disease

When the liver is damaged, it stops producing the proteins required for blood clotting. For example, cirrhosis is the result of continuous long-term damage, and bruising easily is a symptom.

However, it should not appear in isolation and may appear alongside fatigue, appetite loss, abdominal pain, and nausea.

A person with kidney disease bruises easily due to a loss of skin elasticity.

Medications can also hinder the blood clotting process and inhibit platelet function. Ecchymosis, which occurs when blood leaks from a broken capillary into surrounding tissue, is common and requires a preventive treatment plan.

Anyone who suspects liver or kidney disease should consult a doctor.

Other causes

Cancer treatments, such as chemotherapy and targeted therapy, may also lead to bruising. This is because they lower the amount of platelets in the blood.

Easy bruising and bleeding are common leukemia symptoms. They generally affect the back, legs, and hands. Another indication of possible leukemia is lots of bruises with no indication as to a cause. Bruises that take longer than usual to disappear are another concern.

Bernard-Soulier syndrome is a rare, inherited blood clotting disorder. People with this condition bruise easily, with bleeding from small blood vessels under the skin.

Gardner-Diamond syndrome is a condition wherein painful and unexpected bruising occurs, mainly on the arms, legs, or face. It mostly occurs in females who have a mental health condition or emotional stress. Management typically involves psychiatric treatment.

Doctors will check a woman’s platelet levels throughout a pregnancy term, but bruising could be a symptom of gestational thrombocytopenia, which leads to a low platelet count.

This occurs in 4.4% to 11.6% of pregnancies. This accounts for around 75% of all cases of thrombocytopenia in pregnancy.

Always mention any unusual bruising during pregnancy to a doctor or midwife.

It is impossible to completely prevent bruising. Bruises are often harmless, but they can sometimes indicate a medical condition that requires medical treatment.

For example, a person should see a doctor if:

  • bruising occurs for no apparent reason and does not heal within a few weeks
  • bruises appear in unusual locations, such as the torso, back, or face
  • there are a number of bruises in one specific area, or a cluster scattered on different parts of the body
  • there are recurring bruises
  • bruising appears with other symptoms, such as fatigue, nausea, or a high temperature

Occasional bruising is rarely a cause for concern. However, if the discoloration does not heal within a few weeks, it is worth talking to a doctor. There may be a blood clotting issue or another underlying condition that needs treatment.

Taking certain medications and growing older are often at the root of the problem. However, if a person experiences other symptoms alongside random bruising, further investigation may be necessary.