Bruise (Contusion)
Skin discoloration from bleeding under the skin after an injury
Quick Facts
- Type: Soft tissue injury
- Cause: Broken small blood vessels under the skin
- Healing time: Usually 1 to 2 weeks
- Color changes: Red to purple to green to yellow
Overview
A bruise, medically called a contusion, forms when a bump, blow, or other injury damages the tiny blood vessels (capillaries) beneath the skin. Blood leaks out of these vessels into the surrounding tissue, where it shows through the skin as a discolored mark. The skin itself is not broken, which is what separates a bruise from a cut or scrape.
Bruises are extremely common and usually minor, healing on their own over one to two weeks. As the leaked blood is broken down and reabsorbed, the bruise changes color from red or purple to green, yellow, or brown before fading completely. Deeper bruises in muscle or bone can be more painful but follow the same general healing process.
Symptoms
A bruise typically goes through a recognizable sequence:
- Initial pain or tenderness at the injured spot
- A red or pinkish mark that appears soon after the injury
- A change to blue, purple, or black over the next day or two
- A shift to green, then yellow or brown as it heals
- Mild swelling in the area
Most bruises are sore to the touch but cause no other problems. A bruise that is very large, extremely painful, or rapidly swelling, or one that limits movement of a limb, may point to a deeper injury that needs evaluation.
Causes
Bruises are caused by anything that breaks small blood vessels under the skin without breaking the skin itself:
- Bumps and falls: The most common cause, especially over bony areas.
- Sports and physical activity: Collisions, tackles, or being hit by equipment.
- Pinching or pressure: Tight clothing, tools, or accidental knocks.
Some people bruise more easily because of thinner skin, aging, certain medicines that thin the blood, or underlying conditions affecting blood clotting. Frequent bruising without a clear cause can occasionally signal a blood or platelet problem.
Risk Factors
- Older age, as skin and blood vessels become more fragile
- Taking blood-thinning medicines, aspirin, or some supplements
- Long-term corticosteroid use, which thins the skin
- Heavy alcohol use
- Conditions that affect clotting or platelets, such as low platelet counts
- Vitamin C or vitamin K deficiency
Diagnosis
Most bruises need no testing and are diagnosed simply by their appearance and the history of an injury. A clinician may look more closely when bruising is unusual:
- Examination: Checking the size, location, and tenderness, and ruling out a fracture or deeper injury.
- Blood tests: If a person bruises very easily or for no clear reason, tests may check platelet counts and clotting function.
- Imaging: X-rays or other scans if a broken bone or deep tissue injury is suspected.
Treatment
Most bruises heal on their own, and simple home care speeds comfort and recovery. The classic approach is often summarized as rest, ice, compression, and elevation:
- Rest: Protect the area and avoid further injury.
- Ice: Apply a cold pack wrapped in cloth for short periods in the first day or two to limit swelling.
- Compression: A gentle elastic wrap can reduce swelling for larger bruises.
- Elevation: Raising the bruised limb above heart level helps drain fluid.
- Pain relief: Acetaminophen is generally preferred; some pain relievers that thin the blood may worsen bruising.
After the first day or two, gentle warmth may help the body clear the bruise.
Prevention
- Wear protective gear during sports and high-risk activities
- Keep walkways clear and well lit to prevent falls
- Use padding on furniture corners in homes with young children or older adults
- Review blood-thinning medicines with a doctor if you bruise easily
- Eat a balanced diet with adequate vitamin C and vitamin K
When to See a Doctor
See a doctor if you have a bruise that is unusually large, very painful, or not healing after about two weeks, or if you notice frequent bruises with no clear cause. Seek prompt care if you have:
- A bruise with severe swelling and inability to move a limb, which may signal a fracture or trapped pressure
- Bruising along with bleeding from the gums or nose, blood in urine or stool, or tiny red spots on the skin
- A large, painful, firm lump within a bruise (a hematoma)
These can point to a deeper injury or a bleeding problem that needs evaluation.
Frequently Asked Questions
Why does a bruise change color?
A bruise changes color as the body breaks down the blood that leaked into the tissue. It typically starts red, turns blue or purple, then green, and finally yellow or brown before fading. These color changes are a normal part of healing.
How long does a bruise take to heal?
Most bruises fade within about one to two weeks. Larger or deeper bruises, and those in older adults, may take longer. A bruise that has not improved after two weeks is worth having checked.
Should I use ice or heat on a bruise?
Use ice in the first day or two to limit swelling and bleeding under the skin. After that, gentle warmth can improve blood flow and help the body clear the bruise. Always wrap ice or heat packs in cloth to protect the skin.
When is a bruise a sign of something serious?
Frequent bruises without injury, very large or painful bruises, or bruising along with other bleeding such as nosebleeds, bleeding gums, or blood in urine or stool can signal a clotting or platelet problem and should be evaluated by a doctor.
Can certain medicines make me bruise more easily?
Yes. Blood thinners, aspirin, some supplements, and long-term steroid use can all make bruising more likely. If you notice more bruising after starting a medicine, mention it to your doctor rather than stopping the medicine on your own.
References
- Mayo Clinic. Bruise: First aid.
- MedlinePlus, U.S. National Library of Medicine. Bruise.
- American Academy of Dermatology Association. Bruises.
- MedlinePlus, U.S. National Library of Medicine. Easy bruising.