Bruise (Contusion)

How a bruise forms

A blunt force crushes small blood vessels (capillaries and venules) under intact skin. Blood seeps into the surrounding tissue. Pressure and inflammation cause pain and swelling. The body then breaks down the pooled blood: hemoglobin is converted into biliverdin (green) and then bilirubin (yellow), before being cleared.

Bruise color stages

Timing varies with age, depth, size and skin tone, so bruise color cannot reliably date an injury. Bruises can also travel downward with gravity, so a knee bruise may appear on the shin.

Types of contusion

Skin and soft tissue

The common bruise. A larger collection of blood forming a raised lump is a hematoma.

Muscle contusion

A direct blow to a muscle, such as a "charley horse" in the thigh from a knee in sports. It causes pain, swelling, stiffness and reduced movement. See quadriceps contusion. Rarely, bone forms within the bruised muscle (myositis ossificans), causing a hard, painful lump weeks later.

Bone bruise

Bleeding within the bone, seen on MRI after knee and ankle injuries. It causes deep pain that can last weeks to months.

Lung contusion

A pulmonary contusion is bruising of the lung tissue after a strong blow to the chest, such as a car crash or fall from height. Blood and fluid fill the air spaces, causing breathlessness, chest pain, coughing blood and low oxygen. It typically worsens over the first 24 to 72 hours, and complications include pneumonia and acute respiratory distress syndrome. Treatment is supportive: oxygen, pain control to allow deep breathing, careful fluid management and sometimes ventilation. Most contusions resolve in about a week.

Heart contusion

A cardiac contusion (blunt cardiac injury) results from a heavy chest blow, such as a steering wheel impact. It can cause chest pain, irregular heart rhythms and, rarely, heart failure. Doctors use an ECG, blood tests (troponin) and an echocardiogram, and monitor heart rhythm. Most recover fully. A chest bruise "around the heart" from an everyday knock is usually only a chest wall bruise.

Brain contusion

Bruising of the brain after head injury, which can cause confusion, drowsiness and neurological problems and needs a CT scan.

Contusion vs crush injury

A contusion is bruising from a blunt blow, with damage limited to blood vessels and tissue near the point of impact. A crush injury involves sustained compression of a body part, often for minutes to hours, damaging large amounts of muscle. Crush injuries can cause compartment syndrome and crush syndrome, in which muscle breakdown products damage the kidneys and heart. They need hospital care.

Bruising without injury

Unexplained or easy bruising can be a sign of:

• blood thinners, aspirin, NSAIDs, steroids, some supplements (fish oil, ginkgo)
• aging skin and sun damage (senile purpura on the forearms)
• low platelets (thrombocytopenia) from immune thrombocytopenia, leukemia or other causes
• inherited bleeding disorders such as von Willebrand disease or hemophilia
• liver disease
• vitamin C or K deficiency
• abuse, particularly in children, older adults and vulnerable people

A doctor may check a blood count, clotting tests and liver function.

Treatment for a bruise

In the first 48 hours

• Rest the area.
• Ice: wrap ice or a cold pack in a cloth and apply for 15 to 20 minutes every 1 to 2 hours while awake.
• Compression: an elastic bandage for limb bruises, not too tight.
• Elevation: raise the bruised area above heart level.
• Pain relief: acetaminophen (paracetamol) is preferred initially. NSAIDs such as ibuprofen are also used; follow the label dose and avoid them if you have bleeding problems or take blood thinners.

After 48 hours

• Warm compresses can help clear pooled blood.
• Gentle stretching and movement for muscle contusions.
• Arnica gel and vitamin K creams are widely used, with limited evidence.

Muscle contusion

Keep the injured muscle gently stretched (for example, the knee bent for a thigh contusion) for the first 24 hours, avoid massage, heat and alcohol early on, and return to sport gradually with physical therapy.

Frequently asked questions

How long does a bruise take to heal?

Most skin bruises fade within about 2 weeks, moving through red, purple, green and yellow. Larger or deeper bruises, bruises on the legs and bruises in older adults take longer. Bone bruises can ache for several weeks to months.

What is the difference between a contusion and a bruise?

They mean the same thing. Contusion is the medical term for a bruise: bleeding into tissue from a blunt injury without broken skin. Doctors also use contusion for bruising of muscles, bones and organs such as the lungs, heart or brain.

What is a lung contusion?

A lung contusion is bruising of the lung after a strong chest impact. Blood and fluid fill air spaces, causing breathlessness, chest pain and sometimes coughing blood. It often worsens over 1 to 3 days and needs hospital monitoring, but usually heals within about a week.

Can a bruise on the chest affect the heart?

An everyday knock to the chest usually only bruises the chest wall. A major impact, such as a car crash, can bruise the heart itself (cardiac contusion), causing chest pain and abnormal heart rhythms. This needs an ECG, blood tests and monitoring in hospital.

When should I worry about a bruise?

See a doctor for bruises that appear without injury, keep growing, are very large or painful, do not improve after 2 weeks, or come with bleeding gums, nosebleeds or blood in urine or stool. Seek emergency care for bruising after major chest or head trauma.