Is It Just a Bruise? Why Your Body Is Trapping Blood (Hematoma) and Your Medically Vetted Next Steps

Most of us have had a bruise. You bump into a table, your skin turns purple or blue, and over a few days it fades. But sometimes what looks like a simple bruise is actually something called a hematoma.

A hematoma happens when blood leaks out of a damaged blood vessel and becomes trapped under the skin or inside the body. Instead of spreading out evenly like a typical bruise, the blood collects in one area, forming a pocket. Depending on where it forms and how large it is, a hematoma can range from mild and harmless to serious and even life-threatening.

Understanding the difference matters.

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What Exactly Is a Hematoma?

A hematoma is a localized collection of blood outside of blood vessels. It can occur anywhere in the body, including:

• Under the skin
• Inside a muscle
• Under a fingernail or toenail (subungual hematoma)
• In the abdomen
• Inside the skull (intracranial hematoma)

Most hematomas happen after an injury. Even a small bump can damage tiny blood vessels (capillaries), allowing blood to pool. In some cases, larger blood vessels are involved.

How Is a Hematoma Different from a Bruise?

A typical bruise (contusion):

• Is flat
• Spreads out under the skin
• Gradually changes color and fades
• Is usually mildly tender

A hematoma:

• May feel firm or raised
• Can swell noticeably
• May cause more intense pain
• Can take longer to resolve

Think of it this way: all hematomas are caused by bleeding under the skin, but not all bruises are true hematomas.

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Why Is Your Body "Trapping" Blood?

Your body isn't trying to trap blood on purpose. It's responding to injury.

When a blood vessel breaks:

1. Blood leaks into surrounding tissue.
2. Your body activates clotting to stop the bleeding.
3. The blood gets sealed off in the tissue.

The trapped blood can't easily return to circulation, so it stays there until your body slowly breaks it down and reabsorbs it. That process can take days to weeks — sometimes longer if the hematoma is large.

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Common Causes of a Hematoma

Hematomas most often happen after:

• Falls or direct blows
• Car accidents
• Sports injuries
• Surgical procedures
• Blood draws
• Dental work

Certain factors increase your risk:

• Taking blood thinners (like warfarin or direct oral anticoagulants)
• Aspirin or anti-inflammatory medications
• Bleeding disorders
• Older age (blood vessels become more fragile)
• Heavy alcohol use

If you develop frequent or unexplained hematomas, that's something a doctor should evaluate.

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Types of Hematomas and What They Mean

Not all hematomas are equal. Location matters.

1. Subcutaneous Hematoma (Under the Skin)

This is the most common type. It appears as a swollen, tender lump and changes color over time.

Usually not dangerous unless:

• It continues growing
• Pain worsens significantly
• There are signs of infection (redness, warmth, fever)

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2. Subungual Hematoma (Under a Nail)

If you've ever slammed your finger in a door and seen dark blood collect under your nail, that's a subungual hematoma.

It can cause:

• Intense throbbing pain
• Pressure under the nail
• Black or dark purple discoloration

If you notice blood trapped under your nail and want to understand whether it requires immediate attention, Ubie's free AI-powered Subungual Bleeding symptom checker can help you assess your symptoms and determine the right next steps.

Large or painful subungual hematomas may need medical drainage.

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3. Muscle Hematoma

These form deeper in the tissue and may cause:

• Swelling
• Reduced movement
• Increasing pain

Athletes experience these more frequently. Most heal with rest, but large ones may require imaging.

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4. Abdominal Hematoma

This can happen after trauma or surgery. Symptoms may include:

• Abdominal pain
• Swelling
• Weakness or dizziness

This type requires prompt medical evaluation.

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5. Intracranial Hematoma (Inside the Skull)

This is the most serious type. It may occur after even a seemingly minor head injury.

Watch for:

• Severe headache
• Confusion
• Vomiting
• Drowsiness
• Slurred speech
• Weakness on one side

An intracranial hematoma is a medical emergency. Seek immediate care.

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When Is a Hematoma Serious?

Most skin-level hematomas are not dangerous. But you should seek medical attention immediately if you notice:

• Rapid swelling
• Increasing pain
• Numbness or tingling
• Signs of infection (fever, spreading redness)
• A head injury followed by neurological symptoms
• You are on blood thinners and develop a large hematoma
• The hematoma keeps growing

If something feels "off," trust that instinct and speak to a doctor.

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What Are the Medically Recommended Next Steps?

For mild hematomas, doctors typically recommend conservative care.

The RICE Method

• Rest – Avoid stressing the injured area.
• Ice – Apply for 15–20 minutes at a time, several times a day.
• Compression – Light wrapping may reduce swelling.
• Elevation – Keep the area raised above heart level if possible.

These steps help reduce bleeding and swelling in the early stages.

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Pain Relief

• Acetaminophen is generally preferred.
• Avoid NSAIDs (like ibuprofen) in the first 24–48 hours unless your doctor says otherwise, as they can increase bleeding.

If you're on blood thinners, check with your doctor before taking anything new.

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When Drainage Is Needed

Some hematomas, particularly:

• Large subungual hematomas
• Large painful skin hematomas
• Post-surgical hematomas

may require a healthcare provider to drain the collected blood. This is usually a minor procedure but should not be done at home.

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Imaging Tests

If your doctor suspects a deeper hematoma, they may order:

• Ultrasound
• CT scan
• MRI

These tests help determine size and location.

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How Long Does a Hematoma Take to Heal?

Healing depends on size and location:

• Small superficial hematoma: 1–2 weeks
• Larger soft tissue hematoma: Several weeks
• Deep or surgical hematoma: Longer, depending on severity

Color changes are normal:

• Red → Blue/Purple → Green → Yellow → Brown

If the lump remains hard or doesn't shrink over time, follow up with your doctor.

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Can a Hematoma Turn Into Something Worse?

Most resolve without complications. However, possible issues include:

• Infection
• Calcification (hardening over time)
• Compartment syndrome (rare but serious pressure buildup)
• Ongoing bleeding

These complications are uncommon but require medical care.

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How to Lower Your Risk

You can reduce your chances of developing problematic hematomas by:

• Wearing protective gear during sports
• Preventing falls (especially if older)
• Reviewing medications with your doctor
• Managing bleeding disorders carefully

If you notice frequent unexplained hematomas, don't ignore it. That may signal an underlying issue.

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The Bottom Line

A hematoma is more than just a typical bruise — it's a pocket of trapped blood. Most are mild and heal on their own. But location, size, and symptoms matter.

Pay attention if you notice:

• Increasing pain
• Rapid swelling
• Neurological symptoms
• Signs of infection
• A head injury followed by changes in alertness

In those situations, don't wait.

If you're unsure whether what you're seeing is a simple bruise or something more serious — especially with nail discoloration — consider using a trusted online tool like the symptom check for Subungual Bleeding to guide your next steps.

And most importantly: if there is any possibility that your hematoma could be serious or life-threatening, speak to a doctor immediately. Early evaluation can prevent complications and protect your health.

Your body is remarkably good at healing itself — but sometimes it needs a little medical help.