Blood clots and bruises both involve blood issues that lead to noticeably discolored skin. Important differences between the two exist, however. Keep reading to learn more about the difference between bruises and clots.

What are bruises?

Bruises, or contusions, are discolorations of the skin. They occur when small blood vessels called “capillaries” burst. This traps blood below the skin’s surface. Bruises often occur due to trauma to the bruised area from a cut, blunt force, or bone fractures.

Bruises can occur on many parts of the body. They’re usually only a little painful, but sometimes they can be painless or extremely painful.

When you have a bruise, the skin sometimes takes a blackish, bluish appearance due to a lack of oxygen in the area of a bruise. As the bruise heals, the color of the bruise will change, becoming red, green, or yellow before it disappears.

Bruises just under the skin are called “subcutaneous.” They can also occur within muscles. If they occur on bones, they’re referred to as “periosteal.” More bruises tend to be subcutaneous.

What are blood clots?

Blood clots are semisolid masses of blood. Like bruises, they form when a blood vessel is injured by trauma from blunt force, a cut, or excess lipids in the blood. When you’re injured, cell fragments called platelets and proteins in blood plasma will stop the injury from bleeding. This process is called coagulation, and it forms clots. Clots usually dissolve naturally. Sometimes, however, the clots don’t naturally dissolve. That can cause long-term problems. When this happens, it’s called “hypercoagulation” and you should go to your doctor for treatment.

Bruises can happen in a variety of places throughout the body, but the symptoms are usually consistent regardless of where the bruise occurs.

Many bruises change colors as time progresses. Initially, they’re reddish. Then, they’ll often turn dark purple or blue after a few hours. As the bruise heals, it will typically become green, yellow, or lime. A bruise is usually painful at first and may feel tender. As the color fades, the pain usually goes away.

They may produce different symptoms depending on where they are. Blood clots can occur in a wide variety of places throughout the body:

  • A blood clot in the lung, or pulmonary embolus, can cause chest pain, shortness of breath, and sometimes an increased rate of breathing.
  • A blood clot in the leg vein, or deep vein thrombosis (DVT), lead to tenderness, pain, possible redness, and inflammation of the leg.
  • A blood clot in the artery of the leg can cause the leg to feel cold and appear pale.
  • A blood clot in the artery of the brain, or stroke, can cause vision loss, a loss of speech, and weakness on one side of the body.
  • A heart attack, which is a blood clot in the coronary artery, can cause nausea, difficulty breathing, sweating, and pain in the chest.
  • Mesenteric ischemia, or a blood clot in the artery to the intestine, leads to nausea, blood in the stool, and stomach pain.

Learn more: How to tell if you have a blood clot »

Risk factors for bruises

It’s unlikely that you’ll never have a bruise. Some people, though, may be more likely to develop bruises. Risk factors for bruising include:

  • taking anticoagulants that thin the blood such as warfarin (Coumadin)
  • taking medications like aspirin or ibuprofen (Advil, Motrin IB) that can subtly thin the blood
  • having a bleeding disorder
  • bumping into a hard surface, which you may or may not remember
  • having thinner skin and more fragile blood vessels due to older age
  • having a vitamin C deficiency, or scurvy
  • being physically abused

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Risk factors for blood clots

Many different factors increase the risk of blood clot formation.

Lifestyle factors

Lifestyle factors that increase the risk of clotting include:

  • being overweight or obese
  • smoking tobacco
  • being pregnant
  • sitting for prolong periods
  • resting in bed for prolonged periods
  • using therapies that modify hormones, such as birth control and hormone replacement
  • having had a recent trauma or surgery

Genetic factors

Genetic factors also contribute to high levels of blood clotting. You’re more likely to experience blood clots if you have:

  • a history of blood clots before age 40
  • family members with a history of harmful blood clots
  • one or more miscarriages

Blood clots usually occur because proteins and other substances involved in blood clotting aren’t functioning properly.

Diseases that increase your risk

Some diseases can also increase the risk of clotting. They include:

You should see your doctor if you have severe pain or unexplained bruising. Your doctor will ask you questions to obtain a thorough medical history and find clues as to why you have symptoms. They’ll also perform a physical exam and check your vital signs. If bruising is frequent and without an underlying cause, your doctor will evaluate blood to look for a disorder. If you have severe swelling or inflammation, your doctor may use an X-ray to check for any broken or fractured bones. Patterns of bruises and bruises in different stages of healing may indicate physical abuse.

Doctors will usually run more tests for blood clotting and look for thrombi in arteries and veins. They may order:

Because blood clots can occur in a wide variety of places, your doctor may choose certain tests depending on where they suspect a clot is located.

Doctors don’t usually have a special treatment for bruises. They’ll likely recommend common home remedies such as icing the bruised area and then applying heat to it. Pain-reducing medications such as aspirin may also help.

If your doctor hears something in your history that may indicate a reason for your bruising, they’ll do further tests to identify or eliminate possible causes of the bruise.

If you have a blood clot, your doctor might prescribe medications to treat the clot. They’ll use blood thinners in a sequential treatment plan. For the first week, they’ll use heparin to quickly treat the clot. People typically receive this medication as an injection under the skin. Then, they’ll prescribe a medication called warfarin (Coumadin). You typically take this medication by mouth for three to six months.

Both blood clots and bruises can range from minor to severe, and their effects on the body are different. Typically, blood clots can lead to more serious health problems. Seek immediate medical help if you suspect you have a blood clot.

You can reduce your risk for blood clots by doing the following:

  • Maintain a healthy body weight.
  • Reduce or quit smoking altogether.
  • Exercise regularly.
  • Avoid sitting or lying down for long periods.
  • Take all medication as prescribed by your doctor.

Similarly, you can take measures to prevent bruising. They include the following:

  • Move furniture away from doorways and other places where you walk.
  • Make sure rooms and floors are clear.
  • Wear protective gear when you play contact sports, such as football and rugby.
  • Get sufficient vitamin C.

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