Most hematomas heal on their own with basic home care: ice, compression, elevation, and rest. A hematoma is a pool of blood that collects outside a blood vessel after an injury, and it differs from an ordinary bruise because it involves enough blood to form a noticeable, often firm lump under the skin. Small hematomas on an arm or leg typically resolve within two weeks, while larger or deeper ones can take significantly longer and sometimes need medical drainage.
How a Hematoma Differs From a Bruise
A regular bruise happens when tiny capillaries under the skin break and leak a small amount of blood into surrounding tissue. A hematoma involves a larger volume of blood pooling in one area, often from damage to a bigger vessel. That’s why hematomas tend to feel swollen, firm, or even hard to the touch, while a bruise is mostly flat discoloration. The distinction matters because the pooled blood in a hematoma can press on nearby nerves, muscles, or blood vessels in ways a simple bruise won’t.
Immediate First Aid: The RICE Method
The first 24 to 48 hours after injury are the most important window for limiting how large a hematoma becomes. The standard approach is RICE: rest, ice, compression, and elevation.
- Rest. Stop using the injured area. Continued activity pushes more blood through damaged vessels and can expand the hematoma.
- Ice. Apply a cold pack with a cloth barrier between the ice and your skin. Keep it on for 10 to 20 minutes at a time, repeating every hour or two. Cold constricts blood vessels and slows further bleeding into the tissue.
- Compression. Wrap the area gently with an elastic bandage. This applies steady pressure that helps contain swelling. If you notice numbness, tingling, or increased pain below the wrap, it’s too tight.
- Elevation. Raise the injured area above heart level whenever possible. Gravity helps fluid drain away from the injury site and reduces throbbing.
Choosing the Right Pain Reliever
Acetaminophen (Tylenol) is generally the safer choice for pain from a hematoma. Anti-inflammatory painkillers like ibuprofen and naproxen can interfere with blood clotting, which may allow more bleeding into the injured area during the early hours. A large Cochrane review found no difference in pain relief between acetaminophen and anti-inflammatory drugs for soft tissue injuries at any time point, from 2 hours out to 7 days. Since the pain relief is equivalent and anti-inflammatories carry a slightly higher risk of stomach irritation, acetaminophen gives you the same benefit with fewer downsides while a hematoma is still forming.
Switching From Ice to Heat
Ice is the priority for the first 24 hours because it limits inflammation and new bleeding. After that initial day, you can switch to warm compresses if they feel more comfortable. Heat increases blood flow to the area, which helps your body reabsorb the pooled blood faster. Some people find alternating between warm and cool compresses works best. There’s no strict rule after the first day; go with whichever feels better and reduces stiffness.
What Normal Healing Looks Like
A hematoma goes through a predictable color progression as your body breaks down the trapped blood. It starts pinkish-red, deepens to dark blue or purple over the first day or two, then gradually shifts to violet, green, dark yellow, and finally a pale yellow before disappearing. A small, uncomplicated hematoma typically resolves in about two weeks. Larger ones, especially those deep in muscle tissue, can take four to six weeks or longer. You should notice the lump getting softer and smaller over time as the blood is reabsorbed.
Hematomas That Need Medical Attention
Most surface-level hematomas are harmless, but certain signs indicate that something more serious is happening. Seek medical evaluation if you notice:
- Numbness, tingling, or weakness near the injury. A hematoma can press on nerves, causing pins-and-needles sensations or loss of strength in the affected limb.
- Skin color changes beyond bruising. If the skin below the hematoma turns white or blue, the pooled blood may be compressing a blood vessel and cutting off circulation.
- Rapidly increasing size or pain. A hematoma that keeps growing or becomes intensely painful in the hours after injury could signal ongoing bleeding from a larger vessel.
- A hematoma under a fingernail or toenail. When blood pools beneath a nail, the pressure in that small space can cause severe, throbbing pain. A provider can drain it through a small hole in the nail, a quick procedure called trephination. This works best within 24 to 48 hours of the injury.
- Hematomas that appear without an obvious injury, or that happen frequently with minimal contact. This can point to a bleeding disorder or a medication side effect worth investigating.
Compartment Syndrome: A Rare but Serious Risk
When a hematoma forms deep inside a muscle, especially in the lower leg or forearm, the swelling can build pressure within the tight tissue compartments that surround muscle groups. This is called compartment syndrome, and it’s a medical emergency. The earliest and most important warning sign is pain that seems out of proportion to the injury, particularly pain that worsens when you stretch the affected muscle. Later signs include numbness, pale skin, and inability to move the limb, but by that point irreversible nerve and muscle damage may already be underway. If you have a deep muscle hematoma and the pain is intensifying rather than gradually improving, get to an emergency room.
When a Hematoma Needs Drainage
A provider may recommend draining a hematoma if it’s large, painful, or not resolving on its own. For surface-level hematomas, this usually involves inserting a needle to aspirate the pooled blood, sometimes guided by ultrasound. The procedure relieves pressure immediately and often speeds recovery significantly.
Hematomas inside the skull are a different category entirely. These result from head trauma and are diagnosed with CT scans. Brain hematomas above a certain size, or those causing neurological symptoms like confusion, severe headache, vomiting, or unequal pupils, require surgical intervention. Any head injury followed by worsening headache, drowsiness, or changes in behavior warrants emergency evaluation, because blood collecting between the skull and brain can become life-threatening within hours.
Helping Your Body Heal Faster
Beyond the basics of ice, compression, and rest, a few practical steps can support recovery. Stay well hydrated, since your circulatory system needs adequate fluid volume to clear the pooled blood efficiently. Avoid alcohol for the first few days, as it dilates blood vessels and can worsen bleeding. Gentle movement of the affected area after the first 48 hours, as long as it isn’t painful, helps maintain circulation without stressing the injury. If the hematoma is on a limb, continue elevating it at night by propping it on a pillow. Most hematomas resolve completely without any lasting effects, but a large one in muscle tissue can occasionally leave behind a firm spot of scar tissue that softens gradually over weeks to months.