Bruises change colors because your body is breaking down trapped blood in stages, and each stage produces a different pigment. What you’re seeing on your skin is essentially a real-time chemistry experiment: enzymes dismantle hemoglobin (the oxygen-carrying protein in red blood cells) into a series of byproducts, each with its own distinct color. A typical bruise cycles through red, purple, green, yellow, and brown before fading completely, usually over about two weeks.
What Happens Under the Skin
When you bump into something hard enough to damage small blood vessels beneath the skin, blood leaks out into the surrounding tissue. Those escaped red blood cells can’t circulate back into your bloodstream. Instead, they’re stuck, and your immune system sends specialized cleanup cells called macrophages to break them down and recycle the components. The color changes you see on the surface reflect exactly where the macrophages are in that cleanup process.
The key molecule driving the whole color show is heme, the iron-containing part of hemoglobin. As macrophages digest the trapped blood cells, enzymes convert heme into a chain of byproducts, each a different shade. Think of it like autumn leaves: the green chlorophyll fades and reveals the yellows and oranges that were always there. In a bruise, each new pigment literally replaces the last one as enzymes do their work.
The Color Stages, Explained
Red to Purple (Minutes to Hours)
A fresh bruise looks red or pinkish because the hemoglobin in the leaked blood still carries oxygen, giving it the same bright red color as the blood inside your veins and arteries. Within minutes, that oxygen gets released into surrounding tissues. Without oxygen, hemoglobin darkens, and the bruise shifts to a deep purple or blue. This is the stage most people notice first, since the initial reddish phase is brief.
Green (Days 5 to 7)
As macrophages break down hemoglobin over the next several days, an enzyme called heme oxygenase converts heme into a pigment called biliverdin. Biliverdin is green, which is why bruises often develop a greenish tinge around the edges before the center has caught up. You might see purple in the middle and green on the outside at the same time, because the outer edges, where less blood pooled, get processed faster.
Yellow (Days 7 to 10)
A second enzyme, biliverdin reductase, then converts that green biliverdin into bilirubin, which is yellow. This is the same pigment that causes jaundice in newborns. At this stage the bruise often looks yellowish or has a faded, sallow appearance. Many people find this the least attractive phase, but it’s actually a sign that healing is well underway.
Brown to Gone (Days 10 to 14+)
The final byproduct is hemosiderin, a protein that stores the leftover iron from the dismantled hemoglobin. Hemosiderin has a rusty, brownish-yellow color thanks to that iron content. In most cases, the body gradually disperses hemosiderin as the tissue finishes healing, and the bruise fades completely. A typical bruise resolves in about two weeks, though larger or deeper ones can linger. In some cases, particularly with severe injuries or in people with circulation problems, hemosiderin staining can persist for months or even longer, sometimes darkening to a deep brown.
Why Some Bruises Look Different Than Others
Not every bruise follows the textbook color sequence in a neat, predictable way. Several factors can change how a bruise looks and how long it takes to heal.
Depth of the injury: A bruise deep in the muscle tissue may look more blue or purple and take longer to show surface color changes, because the light has to pass through more layers of skin and tissue. Shallow bruises tend to cycle through colors faster and appear more vivid.
Skin tone: The standard red-to-purple-to-green-to-yellow progression is easiest to see on lighter skin. On darker skin, bruises can be harder to detect visually, which is a recognized issue in medical and forensic settings. The underlying chemistry is identical, but melanin in the skin filters the visible color. Bruises on darker skin may appear darker brown or black rather than the classic purple, and the green and yellow stages can be subtle or invisible to the eye.
Medications: Aspirin and other blood-thinning medications interfere with clotting, which means more blood leaks out before the damaged vessels seal off. The result is a bruise that’s larger, darker, and slower to heal. If you take blood thinners and notice bigger bruises than you used to get, that’s the reason.
Age: As you get older, your skin thins and loses some of the fatty layer that cushions blood vessels. This makes vessels more vulnerable to damage and bruises more frequent and visible. The healing process itself also slows down, so each color stage may last longer.
Multiple Colors at Once
It’s common to see two or three colors in a single bruise at the same time, and this sometimes alarms people. The explanation is straightforward: different parts of the bruise are healing at different rates. The edges, where less blood accumulated, get cleaned up first. So you might see yellow at the perimeter, green a bit further in, and purple still lingering at the center where the impact was greatest. This patchwork effect is normal and simply reflects the macrophages working their way inward.
Very large bruises can look especially dramatic because the color gradient is spread across a wider area. A bruise on your thigh from a hard fall might show three or four distinct color bands, almost like a fading sunset. It looks alarming, but it’s the same process as a small bruise on your arm, just scaled up.
When a Bruise Signals Something Deeper
Ordinary bruises from bumps and falls are harmless, even when they look dramatic. But certain patterns deserve attention. Bruises that appear frequently without any clear cause, or that seem disproportionately large compared to minor impacts, can sometimes point to clotting disorders or nutritional deficiencies. Bruises that come with muscle weakness, tingling, numbness, or skin color changes from poor circulation may indicate a deeper issue.
A hematoma, which is a larger, more organized collection of blood under the skin or in organs, is a more serious version of a bruise. Most hematomas near the skin surface resolve on their own, but hematomas inside the skull or abdomen are medical emergencies. Warning signs of a dangerous internal hematoma include a sudden severe headache, one-sided weakness or paralysis, trouble speaking or swallowing, seizures, chest pain, difficulty breathing, or loss of consciousness. These symptoms need emergency care regardless of whether you see a visible bruise on the surface.