A hematoma and a bruise are related but not the same thing. Both involve blood leaking out of damaged blood vessels, but they differ in scale, depth, and how seriously your body is affected. A regular bruise is a minor, surface-level injury that heals on its own. A hematoma is a deeper, more concentrated pool of blood that can sometimes require medical attention.
How a Bruise Forms
A bruise, also called a contusion, happens when tiny blood vessels (capillaries and small veins) just under your skin break from an impact. Blood seeps into the surrounding tissue and spreads out in a thin layer. That’s what creates the familiar flat, discolored patch you see after bumping into something. The leaked blood stays close to the skin’s surface, which is why you can see the color change so clearly.
Over the course of one to two weeks, your body breaks down the escaped blood and reabsorbs it. That’s why a bruise shifts colors as it heals: red or purple at first, then blue, green, and finally yellow or brown before fading completely. The process is painless aside from some tenderness, and no treatment is needed beyond ice and patience.
What Makes a Hematoma Different
A hematoma is a collection of blood that pools in one spot outside the blood vessel, rather than spreading thinly through the tissue the way a bruise does. Think of the difference between spilling water on a countertop (a bruise) versus water filling a bowl (a hematoma). That pooling creates a distinct lump you can often feel under the skin, sometimes firm or rubbery to the touch.
Hematomas typically involve more blood from larger or deeper vessels, not just the tiny capillaries near the surface. They can form under the skin, deep inside muscles, or even around internal organs and inside the skull. Because the blood is concentrated rather than diffused, hematomas tend to be more painful, more swollen, and slower to heal than ordinary bruises. A simple bruise resolves in about two weeks; a hematoma can take considerably longer, and a large one may need to be drained by a doctor to speed recovery.
Types of Hematomas by Location
Where a hematoma forms determines how serious it is. A subcutaneous hematoma sits just beneath the skin and looks like an oversized, raised bruise. It’s the most common type and usually the least dangerous. A subungual hematoma forms under a fingernail or toenail, often after slamming your finger in a door, and creates painful pressure beneath the nail.
Intramuscular hematomas develop deep inside muscle tissue, often from sports injuries or significant trauma. These can cause stiffness and reduced range of motion in the affected limb. In rare cases, blood pooling inside a tight muscle compartment can compress nerves and blood vessels, a condition called compartment syndrome. This is a medical emergency that may require surgery to relieve the pressure.
The most dangerous hematomas are the ones you can’t see. Epidural and subdural hematomas form inside the skull between the brain and the bone, usually after a head injury. Epidural hematomas sit between the skull and the brain’s outermost protective layer, and they can grow quickly and cause sudden loss of consciousness. Subdural hematomas form slightly deeper, between protective layers closer to the brain itself. Because subdural hematomas can develop slowly over days or weeks, they’re sometimes harder to detect, which is one reason survival rates tend to be lower for this type. Both are life-threatening without treatment.
How to Tell Which One You Have
Most of the time, the difference is obvious by feel. A regular bruise is flat, mildly tender, and fades within two weeks. A hematoma is raised or lumpy, noticeably more painful, and may feel warm or hard. If you press on a bruise, it’s soft. If you press on a hematoma, you’ll often feel a firm mass underneath the skin where blood has collected.
Size matters too. A bruise the size of a quarter from bumping your shin is routine. A swollen, discolored area the size of a baseball that keeps growing or doesn’t start fading after a couple of weeks is behaving more like a hematoma. Pain that seems disproportionate to the injury, or that gets worse rather than better over the first few days, also points toward a hematoma rather than a simple bruise.
Treating a Bruise vs. a Hematoma
For an ordinary bruise, rest, ice, compression, and elevation (the classic RICE approach) is all you need. Apply ice for 15 to 20 minutes at a time during the first day or two to reduce swelling, and the bruise will work itself out.
Small hematomas near the skin’s surface often respond to the same approach, just on a longer timeline. Larger hematomas are a different story. If a hematoma doesn’t shrink on its own within several days, a doctor may drain the pooled blood with a needle or small incision to speed healing and prevent complications like infection or tissue damage. Hematomas under a toenail are sometimes relieved by making a small hole in the nail to release the trapped blood and ease the pressure.
Internal hematomas, particularly those in the skull, chest, or abdomen, require imaging and often surgical intervention. These aren’t injuries you can manage at home.
Warning Signs That Need Immediate Attention
A surface-level bruise or small hematoma on your arm or leg is rarely an emergency. But certain symptoms signal that a hematoma could be forming in a dangerous location or growing large enough to cause complications.
For head injuries, watch for:
- A sudden, severe headache
- Weakness or paralysis on one side of the body or face
- Nausea and vomiting
- Trouble speaking or swallowing
- Loss of balance or coordination
- Seizures or loss of consciousness
For potential internal bleeding in the chest or abdomen:
- Trouble breathing or sudden changes in breathing rate
- Chest or abdominal pain
- Skin turning pale, cold, or clammy
- Severe pain that seems out of proportion to any known injury
You should also pay attention to bruising patterns over time. Bruises that don’t heal within two weeks, frequent unexplained bruising, or bruising accompanied by muscle weakness, tingling, or numbness can all indicate an underlying issue with blood clotting or circulation that’s worth investigating.