A bruise is a patch of discolored skin that forms when small blood vessels beneath the surface rupture from an impact but the skin itself stays intact. Blood leaks into the surrounding tissue, pools between layers of skin, and triggers the familiar progression of colors as your body breaks it down over roughly two weeks. Nearly everyone gets bruises, and most heal on their own without any treatment.
How a Bruise Forms
Three things need to happen for a bruise to appear. First, a force hits your skin, usually something blunt like a doorframe, a ball, or a fall. Second, that force is strong enough to rupture tiny blood vessels called capillaries, but not strong enough to break the skin open. Third, your blood pressure is high enough to push blood out of the damaged vessels and into the connective tissue around them.
Once those vessels break, red blood cells flood into the space between your dermis (the inner layer of skin) and the fat layer beneath it. That area has the most loose connective tissue, which is why blood collects there easily. The escaped red blood cells quickly burst open, releasing hemoglobin, the protein that carries oxygen in your blood. It’s this free hemoglobin sitting in your tissue that creates the visible discoloration.
Why Bruises Change Color
The shifting colors of a bruise aren’t random. They follow a predictable chemical sequence as your body dismantles the hemoglobin trapped in your tissue.
- Red or dark red (first day or two): Fresh blood and intact hemoglobin sit just below the skin surface. The bruise may also look slightly swollen.
- Blue or purple (days 1 through 4): Hemoglobin loses its oxygen and darkens. This is typically when a bruise looks its worst.
- Brown (around days 5 through 7): Hemoglobin breaks down further into a compound called methemoglobin, shifting the color from purple toward brownish tones.
- Green and yellow (roughly days 7 through 14): Your body converts the remaining hemoglobin byproducts into biliverdin (green) and then bilirubin (yellow). These are the same pigments involved when your liver processes old red blood cells normally.
Not every bruise follows this timeline exactly. Deeper bruises can take longer to surface and longer to resolve. Bruises on your legs tend to heal more slowly than those on your arms or face because of gravity and lower circulation. Most bruises fully disappear within two to three weeks.
Why Some People Bruise More Easily
If you feel like you bruise from the lightest bump, several factors could explain it. Age is one of the biggest. As skin matures, it loses connective tissue and the layer of subcutaneous fat that cushions blood vessels. The connective tissue in the dermis can no longer support the tiny blood vessels the way it once did, so even minor contact can cause them to rupture. This type of bruising, sometimes called actinic purpura, is extremely common in older adults and typically shows up on the forearms and backs of the hands.
Nutritional deficiencies also play a role. Vitamin K is essential for producing several clotting factors that help stop bleeding after an injury. When vitamin K levels are low, those clotting factors don’t work properly, and even small injuries can produce noticeable bruises or tiny pinpoint spots of bleeding under the skin. Vitamin C supports collagen production, which helps keep blood vessel walls strong. A significant deficiency weakens those walls and makes them more prone to breaking.
Certain medications increase bruising risk as well. Blood thinners reduce your blood’s ability to clot, so more blood escapes before the leak seals. Anti-inflammatory pain relievers like ibuprofen and aspirin have a similar, milder effect by interfering with platelet function. Some supplements, including fish oil and ginkgo, can also thin the blood enough to cause more frequent bruising. If you notice a sudden increase in bruising after starting a new medication, that connection is worth mentioning to your doctor.
Helping a Bruise Heal Faster
Most bruises don’t need treatment, but you can speed things along and limit how large the bruise becomes. In the first eight hours after the injury, applying ice wrapped in a cloth for 10 to 20 minutes at a time helps constrict blood vessels and reduce the amount of blood that leaks into the tissue. Repeat every hour or two during that initial window. Elevating the bruised area above heart level, when practical, also slows blood flow to the site.
After the first day or two, switching to gentle warmth can help. Heat increases blood flow to the area, which helps your body reabsorb the trapped blood and clear the hemoglobin byproducts more quickly. A warm compress for 10 to 15 minutes a few times a day is usually enough. Avoid massaging a fresh bruise, as that can cause more blood vessel damage and make things worse.
When Bruising Signals Something Deeper
Occasional bruises from known bumps or falls are completely normal. But certain patterns suggest something beyond everyday clumsiness. Large bruises that appear on your torso, back, or face without a clear cause deserve attention, since bruises in these locations are less likely to come from accidental contact. A bruise that lasts longer than two weeks, keeps recurring in the same spot, or comes with a hard lump underneath (a sign that blood has pooled into a dense clot called a hematoma) also warrants a closer look.
Unexplained bruising paired with other bleeding symptoms is a more urgent signal. Frequent nosebleeds, blood in your urine or stool, prolonged bleeding from small cuts, or excessive bleeding during dental work can point to problems with platelet count or clotting factor production. Conditions like certain blood disorders or liver disease can impair your body’s clotting system and make bruising one of the first visible signs. If bruising is new, worsening, or runs in your family alongside easy bleeding, blood work can usually identify or rule out an underlying cause quickly.