A contusion is the medical term for a bruise. It happens when a blow or impact damages small blood vessels beneath the skin, in a muscle, or even in a bone or organ, causing blood to leak into the surrounding tissue. Most contusions are minor and heal on their own, but the term covers a wide range of injuries, from a simple bruise on your shin to a serious bruise on your brain or heart.
How a Contusion Forms
When something strikes your body hard enough to break the tiny veins and capillaries beneath the surface, blood seeps into the surrounding tissue. That pooled blood is what creates the discoloration and tenderness you recognize as a bruise. Unlike a hematoma, where blood collects into a distinct, often raised pocket, a contusion involves blood spreading diffusely through the tissue. That’s why a bruise looks flat and discolored rather than forming a defined lump.
Why Bruises Change Color
The shifting colors of a bruise are a visible timeline of your body breaking down and recycling the leaked blood. Fresh bruises look red or reddish because of the oxygen-carrying protein in red blood cells. Over the next day or two, as those cells break apart and that protein loses oxygen, the bruise darkens to deep purple or brown. Your body then converts the breakdown products into green and yellow pigments, which is why older bruises take on those colors before fading entirely. The whole cycle typically runs about two weeks, though larger or deeper bruises can take longer.
Skin Contusions
The most common type is a simple bruise just beneath the skin. You bump your leg on a coffee table, catch a ball on your forearm, or walk into a door frame, and a bruise appears hours later. These are almost always harmless. They’re tender to the touch, may swell slightly, and go through the color changes described above before disappearing.
Some people bruise more easily than others. Older adults bruise more readily because aging skin loses the fatty layer that cushions blood vessels. Blood-thinning medications also increase bruising, as do certain nutritional deficiencies.
Muscle Contusions and Severity Grades
A harder impact can bruise the muscle tissue itself, which is common in contact sports, falls, and car accidents. Muscle contusions are graded by severity:
- Grade I (mild): Localized pain with minimal swelling and only slight limitation in movement. You can usually continue your activity, and the pain is well defined in one spot.
- Grade II (moderate): Some muscle fibers are torn but not completely ruptured. Pain is harder to pinpoint, swelling is more noticeable, and you’ll likely limp or lose the ability to use the affected muscle normally. Range of motion drops significantly.
- Grade III (severe): The muscle or its tendon is completely ruptured. This causes immediate, intense pain, rapid swelling, and a visible or palpable gap in the muscle. You lose more than half of your normal range of motion, and the injured muscle may visibly shrink compared to the other side.
Grade I and most Grade II muscle contusions heal with rest and basic care. Grade III injuries often require surgical evaluation.
Bone Bruises
Bones can bruise too, even without fracturing. A bone contusion happens when an impact damages the tiny blood vessels inside the bone itself, causing bleeding and swelling within the rigid bone structure. These injuries don’t show up on X-rays. They’re only visible on MRI, which is why they sometimes go undiagnosed initially.
Bone bruises are common alongside ligament injuries, particularly in the knee. They hurt more and last far longer than skin bruises. Research on bone bruises associated with knee ligament tears shows that the bruise volume starts decreasing around four weeks after injury, but full healing can take several months. During that time, the area remains painful with weight-bearing or pressure.
Organ Contusions
Contusions can also affect internal organs, and these are the most serious type. They almost always result from significant trauma like car accidents, hard falls, or direct blows to the chest or abdomen.
A heart contusion (myocardial contusion) bruises the heart muscle itself. Symptoms include chest pain, shortness of breath, lightheadedness, heart palpitations, and nausea. Doctors look for abnormal heart rhythms, low blood pressure, and elevated levels of a protein that leaks from damaged heart muscle cells. Imaging with CT scans or echocardiograms helps confirm the diagnosis.
A brain contusion is a bruise on the brain tissue, distinct from a concussion. While a concussion affects a broad area and causes symptoms like headache, nausea, and ringing in the ears, a brain contusion is more localized and tends to produce focal symptoms: difficulty speaking, trouble concentrating, changes in thinking, localized numbness and tingling, dilated pupils, or movement problems. Both are diagnosed through physical and mental testing along with CT or MRI scans, but a contusion shows visible tissue damage on imaging where a concussion typically does not.
Treatment for Most Contusions
For skin and muscle contusions, the standard approach is rest, ice, compression, and elevation. Ice applied for about 20 minutes at a time, several times a day, helps limit swelling in the first few days. Starting cold therapy within the first 36 hours after injury is more effective than waiting. Elevating the injured area above heart level also reduces swelling by helping fluid drain away from the site.
Compression with an elastic bandage limits additional bleeding into the tissue. Rest doesn’t necessarily mean complete immobilization, but you should avoid activities that stress the injured area until pain and swelling improve. Over-the-counter pain relief can help with discomfort, though you may want to avoid aspirin, which can thin the blood and potentially worsen bruising.
Most simple contusions resolve within two to three weeks. Deeper muscle contusions, especially Grade II injuries, may take four to six weeks. Bone bruises can take two to four months.
Complications Worth Knowing About
Most bruises are uncomplicated, but severe muscle contusions carry two risks worth understanding.
The first is a condition where bone tissue forms inside the damaged muscle, a complication most common in the front of the thigh, the inner thigh, and the upper arm. It typically develops weeks after a significant muscle contusion and causes a firm, painful mass in the muscle. In many cases this resolves on its own over months, but it can limit your range of motion and delay return to activity.
The second and more urgent risk is compartment syndrome, where swelling from the contusion builds pressure inside a closed muscle compartment faster than the body can relieve it. The hallmark sign is pain that feels far worse than the injury should warrant, often described as a deep ache or burning. The affected area feels unusually tense or hard. You may also notice tingling, numbness, or weakness. This is a medical emergency because sustained pressure can cut off blood flow and permanently damage the muscle and nerves. If a contusion produces escalating pain that seems disproportionate to the original injury, especially in the lower leg or forearm, that needs immediate medical attention.