Most hematoma lumps resolve on their own within one to four weeks, depending on their size and location. The lump forms when blood pools and clots beneath the skin after an injury, creating a firm, swollen mass that can be tender and discolored. You can speed up the process at home with a combination of cold therapy, heat, compression, and elevation, but larger or deeper hematomas sometimes need medical drainage.
What to Do in the First 48 Hours
The first two days after the injury are when you have the most influence over how large the hematoma becomes. Your goal during this window is to limit further bleeding into the tissue and reduce swelling. The standard approach is rest, ice, compression, and elevation.
Apply an ice pack with a thin cloth barrier for 10 to 20 minutes every one to two hours while you’re awake. Cold narrows blood vessels and slows the flow of blood into the injured area, which keeps the lump from growing. Between icing sessions, wrap the area with a compression bandage snugly enough to apply gentle pressure but not so tight that you feel numbness or tingling. Keep the injured area elevated above heart level when possible, especially while resting or sleeping. This helps fluid drain away from the lump rather than pooling in it.
For pain during this early phase, stick with acetaminophen rather than ibuprofen, aspirin, or other anti-inflammatory painkillers. These medications interfere with platelet function, which can increase bleeding. Aspirin is the worst offender, suppressing clotting ability for roughly seven days. Ibuprofen’s effect is milder and reverses within about a day, but it’s still worth avoiding while the hematoma is fresh and blood is still accumulating.
Switching to Heat After 48 Hours
Once the injury is more than two days old and swelling has stabilized, heat becomes your primary tool. A warm compress, heating pad, hot water bottle, or warm bath increases blood flow to the area, which helps your body break down and reabsorb the clotted blood faster. Apply heat for 15 to 20 minutes several times a day.
Never use heat on a fresh injury. In the first 48 hours, the extra blood flow makes the hematoma worse. The switch point is straightforward: if the area still feels warm and is actively swelling, keep icing. Once the swelling has plateaued and the acute tenderness has calmed down, transition to heat.
Does Arnica Actually Work?
Arnica gel and creams are widely marketed for bruises and hematomas, but the clinical evidence is surprisingly weak. A meta-analysis of eight studies found that six showed no benefit over placebo. Multiple controlled trials in patients recovering from surgery found no meaningful difference in bruising between arnica and a sugar pill, whether the arnica was applied topically or taken as a homeopathic pill under the tongue.
A few smaller studies did show modest effects. One found that 20% topical arnica ointment reduced bruise healing time compared to petroleum jelly or a vitamin K cream. Another reported a statistically significant reduction in bruising after liposuction. But these results are outliers in a body of evidence that mostly points to arnica performing no better than doing nothing. If you want to try it, a high-concentration topical ointment (not a diluted homeopathic preparation) is the form with the most plausible benefit, but don’t rely on it as your main strategy.
When a Hematoma Needs Medical Drainage
Small hematomas close to the skin’s surface will typically reabsorb without intervention. Larger or deeper ones, particularly those that remain firm and painful after two to three weeks, may need to be drained by a doctor. The procedure involves either making a small incision or using imaging guidance to locate and evacuate the pooled blood.
Location matters too. Hematomas on the ear (common in contact sports) should be drained promptly, ideally within seven days. If left longer than a week, the inflammation can damage cartilage and may require more involved surgical cleanup. Hematomas that recur after initial treatment also typically need specialist evaluation.
A hematoma that sits deep within a large muscle group, such as the thigh or calf, carries more risk than one just beneath the skin. These can take longer to resolve and are more likely to need professional attention if they aren’t shrinking on their own after a few weeks.
When a Lump Turns Hard and Won’t Go Away
If your hematoma lump becomes increasingly firm or hard over several weeks rather than softening and shrinking, it may be developing into a condition called myositis ossificans. This happens when the body’s healing process misfires and produces bone cells instead of muscle cells at the injury site. The result is a bony mass that forms inside the soft tissue, most commonly in the arm or leg.
About four in five cases occur in limb muscles. The lump is typically fast-growing, painful, swollen, and warm to the touch. As it enlarges, it can restrict your range of motion, especially if it’s near a joint. This condition is diagnosed with imaging and may require physical therapy or, in persistent cases, surgical removal once the growth has fully matured. If your hematoma lump is getting harder and bigger rather than smaller after a few weeks, that’s a sign to get it evaluated.
Warning Signs That Need Immediate Attention
Most hematomas are painful but not dangerous. A small number, particularly those caused by significant trauma, can signal a more serious problem. The most concerning complication is compartment syndrome, where pressure from swelling builds up inside a closed muscle compartment and cuts off blood flow. This is a medical emergency.
Get to an emergency room if you notice any of the following after an injury: extreme pain that seems out of proportion to the injury, visible bulging or swelling that keeps getting worse, numbness or tingling below the injury, a burning sensation under the skin, or a muscle that feels unusually full and firm. These symptoms can develop after a fracture, crush injury, or surgery, and they can also occur under a cast or splint that’s too tight. Acute compartment syndrome requires rapid treatment to prevent permanent tissue damage.
Outside of compartment syndrome, signs that a hematoma has become infected include increasing redness that spreads outward from the lump, warmth that intensifies rather than fading, fever, and pus or drainage from the skin over the lump. An infected hematoma needs antibiotics and often drainage.