Black and blue marks are often associated with bruises. A bruise, or contusion, appears on the skin due to trauma. Examples of trauma are a cut or a blow to an area of the body. The injury causes tiny blood vessels called capillaries to burst. Blood gets trapped below the skin’s surface, which causes a bruise.

Bruises can occur at any age. Some bruises appear with very little pain, and you might not notice them. While bruises are common, it’s important to know your treatment options and whether your condition warrants emergency medical attention.

Most bruises are caused by physical injury. Some underlying conditions may make bruising more common. Here are 16 possible causes of bruising.

Warning: Graphic images ahead.

Sport injuries

  • Sport injuries are those that occur during exercise or while participating in a sport.
  • They include broken bones, strains and sprains, dislocations, torn tendons, and muscle swelling.
  • Sport injuries may occur from trauma or overuse.
Read full article on sports injuries.

Concussion

  • This is a mild traumatic brain injury that can occur after an impact to your head or after a whiplash-type injury.
  • Symptoms of a concussion vary depending on both the severity of the injury and the person injured.
  • Memory problems, confusion, drowsiness or feeling sluggish, dizziness, double vision or blurred vision, headache, nausea, vomiting, sensitivity to light or noise, balance problems, and slowed reaction to stimuli are some possible symptoms.
  • Symptoms may begin immediately, or they may not develop for hours, days, weeks, or even months following a head injury.
Read full article on concussions.

Thrombocytopenia

Thrombocytopenia

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  • Thrombocytopenia refers to a platelet count that is lower than normal. It can be caused by a wide variety of conditions.
  • Symptoms vary in severity.
  • Symptoms may include red, purple, or brown bruises, a rash with small red or purple dots, nosebleeds, bleeding gums, prolonged bleeding, blood in the stools and urine, bloody vomit, and heavy menstrual bleeding.
Read full article on thrombocytopenia.

Leukemia

Leukemia
  • This term is used to describe multiple types of blood cancer that occur when white blood cells in the bone marrow grow out of control.
  • Leukemias are classified by onset (chronic or acute) and cell types involved (myeloid cells and lymphocytes).
  • Common symptoms include excessive sweating, especially at night, fatigue and weakness that don't go away with rest, unintentional weight loss, bone pain, and tenderness.
  • Painless, swollen lymph nodes (especially in the neck and armpits), enlargement of the liver or spleen, red spots on the skin (petechiae), bleeding easily and bruising easily, fever or chills, and frequent infections are also possible symptoms.
Read full article on leukemia.

Von Willebrand disease

  • Von Willebrand disease is a bleeding disorder caused by a deficiency of von Willebrand factor (VWF).
  • If your levels of functional VWF are low, your platelets won’t be able to clot properly, which leads to prolonged bleeding.
  • The most common symptoms include easy bruising, excessive nosebleeds, prolonged bleeding after injury, bleeding from the gums, and abnormally heavy bleeding during menstruation.
Read full article on Von Willebrand disease.

Head injury

Head injury

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This condition is considered a medical emergency. Urgent care may be required.

  • This is any sort of injury to your brain, skull, or scalp.
  • Common head injuries include concussions, skull fractures, and scalp wounds.
  • Head injuries are usually caused by blows to the face or head, or movements that violently shake the head.
  • It's important to treat all head injuries seriously and have them assessed by a doctor.
  • Dangerous symptoms that signal a medical emergency include loss of consciousness, seizures, vomiting, balance or coordination problems, disorientation, abnormal eye movements, persistent or worsening headache, loss of muscle control, memory loss, leaking of clear fluid from the ear or the nose, and extreme sleepiness.
Read full article on head injuries.

Ankle sprain

Ankle sprain

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  • This is an injury to the tough bands of tissue (ligaments) that surround and connect the bones of the leg to the foot.
  • It typically happens when the foot suddenly twists or rolls, forcing the ankle joint out of its normal position.
  • Swelling, tenderness, bruising, pain, inability to put weight on the affected ankle, skin discoloration, and stiffness are possible symptoms.
Read full article on ankle sprains.

Muscle strains

Muscle strains

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  • Muscle strains occur when a muscle is overstretched or torn from overuse or injury.
  • Symptoms include sudden onset of pain, soreness, limited range of movement, bruising or discoloration, swelling, a “knotted-up” feeling, muscle spasms, and stiffness.
  • Mild to moderate strains can be successfully treated at home with rest, ice, compression, elevation, heat, gentle stretching, and anti-inflammatory medications.
  • Seek urgent medical attention if the pain, bruising, or swelling doesn’t subside in a week or starts to get worse, if the injured area is numb or bleeding, if you can’t walk, or if you can’t move your arms or legs.
Read full article on muscle strains.

Hemophilia A

  • This is an inherited bleeding disorder in which a person lacks or has low levels of certain proteins called clotting factors, and the blood doesn't clot properly as a result.
  • Disease symptoms are caused by a defect in the genes that determine how the body makes clotting factors VIII, IX, or XI.
  • Deficiency of these factors causes easy bleeding and trouble with blood clotting in affected individuals.
  • Spontaneous bleeding, easy bruising, nosebleeds, bleeding gums, prolonged bleeding after surgery or injury, bleeding into joints, internal bleeding, or bleeding in the brain are other possible symptoms.
Read full article on Hemophilia A.

Christmas disease (hemophilia B)

Christmas disease

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  • With this rare genetic disorder, the body produces little or no factor IX, causing the blood to clot improperly.
  • It's usually diagnosed in infancy or early childhood.
  • Prolonged bleeding, unexplained, excessive bruising, bleeding from the gums, or prolonged nosebleeds are some of the symptoms.
  • Unexplained blood may appear in the urine or feces, and internal bleeding may pool in the joints, which causes pain and swelling.
Read full article on Christmas disease (hemophilia B).

Factor VII deficiency

  • This occurs when the body either doesn't produce enough factor VII or something is interfering with the production of factor VII, often another medical condition or medication.
  • Symptoms include abnormal bleeding after giving birth, having surgery, or being injured; easy bruising; nosebleeds; bleeding gums; and heavy or prolonged menstrual periods.
  • In more severe cases, symptoms can include destruction of cartilage in joints from bleeding episodes and bleeding in the intestines, stomach, muscles, or head.
Read full article on factor VII deficiency.

Factor X deficiency

  • Factor X deficiency, also called Stuart-Prower factor deficiency, is a condition caused by not having enough of the protein known as factor X in the blood.
  • The disorder may be passed down in families through genes (inherited factor X deficiency) but can also be caused by certain medications or another medical condition (acquired factor X deficiency).
  • Factor X deficiency causes interruptions in blood's normal clotting mechanism.
  • Symptoms include abnormal bleeding after giving birth, having surgery, or being injured; easy bruising; nosebleeds; bleeding gums; and heavy or prolonged menstrual periods.
  • In more severe cases, symptoms can include destruction of cartilage in joints from bleeding episodes and bleeding in the intestines, stomach, muscles, or head.
Read full article on factor X deficiency.

Factor V deficiency

  • This is caused by a lack of factor V, also known as proaccelerin, which is an important part of the blood clotting mechanism.
  • The deficiency causes poor clotting, which leads to prolonged bleeding after surgery or injury.
  • Acquired factor V deficiency may be caused by certain medications, underlying medical conditions, or an autoimmune reaction.
  • Symptoms include abnormal bleeding after giving birth, having surgery, or being injured; easy bruising; nosebleeds; bleeding gums; and heavy or prolonged menstrual periods.
Read full article on factor V deficiency.

Factor II deficiency

  • This is caused by a lack of factor II, also known as prothrombin, which is an important part of the blood clotting mechanism.
  • This very rare blood clotting disorder results in excessive or prolonged bleeding after an injury or surgery.
  • It may be inherited or acquired as a result of disease, medications, or an autoimmune response.
  • Symptoms include umbilical cord bleeding at birth, unexplained bruising, prolonged nosebleeds, bleeding from the gums, heavy or prolonged menstrual periods, and internal bleeding in the organs, muscles, skull, or brain.
Read full article on factor II deficiency.

Varicose veins

Varicose veins

Image by: gilaxia

  • Varicose veins occur when veins aren't functioning properly, causing them to become enlarged, dilated, and overfilled with blood.
  • The primary symptoms are highly visible, misshapen veins.
  • Pain, swelling, heaviness, and achiness over or around the enlarged veins may also occur.
  • In severe cases veins can bleed and form ulcers.
  • Varicose veins most commonly occur in the legs.
Read full article on varicose veins.

Deep vein thrombosis (DVT)

Deep vein thrombosis (DVT)

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This condition is considered a medical emergency. Urgent care may be required.

  • Deep vein thrombosis is a serious condition that occurs when a blood clot forms in a vein located deep inside the body.
  • Symptoms include swelling in the foot, ankle, or leg (usually on one side), cramping calf pain in the affected leg, and severe or unexplained pain in the foot and ankle.
  • Other symptoms include an area of skin that feels warmer than the surrounding skin, and skin over the affected area turning pale or a reddish or bluish color.
  • DVTs may travel to the lungs causing a pulmonary embolism.
Read full article on deep vein thrombosis.

There are three types of bruises based on their location on your body:

  • Subcutaneous bruises occur just beneath the skin.
  • Intramuscular bruises occur in the underlying muscles.
  • Periosteal bruises occur on the bones.

Symptoms of the bruise vary depending on the cause. Discoloration of the skin is often the first sign. While they’re usually black and blue, bruises can also be:

  • red
  • green
  • purple
  • brown
  • yellowish, which most often occurs as the bruise heals

You may also experience pain and tenderness in the area of bruising. These symptoms generally improve as the bruise heals. Read more about the colorful stages of bruises.

Severe symptoms

Other symptoms indicate a more severe condition. Seek medical attention if you have:

  • increased bruising while taking aspirin (Bayer) or other blood thinners
  • swelling and pain in the area of bruising
  • bruising that occurs after a hard blow or fall
  • bruising that occurs along with a suspected broken bone
  • bruising for no reason
  • bruising that fails to heal after four weeks
  • bruising under your nails that’s painful
  • bruising accompanied by bleeding from your gums, nose, or mouth
  • bruising accompanied by blood in your urine, stool, or eyes

Also, see a healthcare provider if you have:

  • unexplained bruising, especially in a recurring pattern
  • bruises that aren’t painful
  • bruises that reappear in the same area without injury
  • any black bruises on your legs

Blue bruises on your legs may come from varicose veins, but black bruises can indicate deep vein thrombosis (DVT), which is the development of a blood clot. This can be life-threatening.

Unexplained bruises that appear on the shin or knee may come from bumping the area on a doorframe, bedframe, post, or chair without noticing.

Other common causes of bruises include:

Bruises that develop after a cut, burn, fall, or injury are normal. It’s not uncommon to develop a knot in the area of bruising. These bruises form as part of your body’s natural healing process. In most cases, they’re nothing to worry about. However, if you have a wound that bruises, reopens, and produces pus, clear liquid, or blood, see a healthcare provider promptly. These can be signs of an infection.

If a child has unexplained bruising, take them to their healthcare provider to determine the cause. Unexplained bruising on a child can be a sign of serious illness or even abuse.

Certain medications also make it more likely for you to bruise. This is especially the case with blood thinners and corticosteroids. Some herbal supplements, such as fish oil, have similar blood-thinning effects and may lead to bruises. You may also notice bruising after receiving an injection or wearing tight clothing.

Bruises also tend to be more common in older adults. As you age, your skin becomes thinner, and the capillaries under your skin become more prone to breaking.

Some people bruise easily, with little impact to their body. Women are also more prone to bruising. In most cases, this is nothing to be alarmed about. However, if this is a recent development, talk to your healthcare provider about potential causes and treatment options.

Bleeding disorders

Sometimes bruising is caused by an underlying condition not related to injury. A number of bleeding disorders can cause frequent bruising. These conditions include:

You may treat bruises at home with some of the following options:

  • Use an ice pack to reduce swelling. Wrap the pack in cloth to avoid putting it directly on your bruised skin. Leave the ice on your bruise for 15 minutes. Repeat this every hour as needed.
  • Rest the bruised area.
  • If practical, raise the bruised area above your heart to keep blood from settling into the bruised tissue.
  • Take an over-the-counter medication, such as acetaminophen (Tylenol), to reduce pain in the area. Avoid aspirin or ibuprofen as they may increase bleeding.
  • Wear tops with long sleeves and pants to protect bruises on your arms and legs.

You probably won’t go through life without ever getting a bruise, but you can prevent some bruising by being cautious while playing, exercising, and driving.

Use pads on your knees, elbows, and shins when cleaning or playing sports to avoid bruising in these areas. Reduce the risk of getting bruised when playing sports by wearing:

  • shin guards
  • shoulder pads
  • hip guards
  • thigh pads

Occasional black and blue marks from bruises are a normal occurrence. Bruises can be uncomfortable, but they usually heal on their own unless they’re associated with a medical condition. See your healthcare provider if a bruise doesn’t improve or resolve within three weeks.