A subungual hematoma is when blood and fluids collect under a fingernail or toenail. It can occur from a traumatic injury when your finger or toe is hit or crushed.
This injury causes the nail to look red, black, or blue. In some cases, you may fracture the bone under the nail.
If the bruise is small and not too painful, it will heal without treatment. If the bruise is large and painful, you may need to have the blood drained.
If a large area of the nail is damaged, your doctor may want to remove it. If they don't remove the nail, it may become loose or fall off in the next 2 weeks. In almost all cases, the nail will grow back from the area under the cuticle called the matrix. This takes a few weeks to start and is complete in about 4 to 6 months for a fingernail and 12 months for a toenail. If the nail bed or matrix was damaged, the nail may grow back with a rough or irregular shape. Sometimes the nail may not regrow at all.
Home care
The following guidelines will help you care for your wound at home:
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Apply an ice pack for no more than 20 minutes every 3 to 6 hours for the first 1 to 2 days. Continue this, as needed, 3 to 4 times a day until the pain and swelling go away. To make an ice pack, put ice cubes in a plastic bag that seals at the top. Wrap the bag in a thin towel and apply to the affected area.
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If the nail was drained:
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Keep the nail covered with a clean adhesive bandage for the next 2 days. There may be some oozing of blood during that time, so change the bandage as needed. Keep the wound dry and clean.
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Rinse the finger or toe once a day under warm running water. Clean any crust away with a cotton-tipped applicator soaked in soapy water.
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If the nail was removed:
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The nail bed (tissue under the nail) is moist, soft, and sensitive. This needs to be protected from injury for the first 7 to 10 days until it dries out and becomes hard. Keep it covered with a dressing or adhesive bandage until that time.
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Bandages tend to stick to a newly exposed nail bed and can be hard to remove if left in place more than 24 hours. Therefore, unless you were told otherwise, change dressings every 24 hours. Apply petroleum jelly and then a nonstick dressing. This will keep the bandage from sticking and make it easier to remove. If necessary, soak the dressing off while holding your finger or toe under warm running water.
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If an X-ray showed a fracture, protect the finger or toe for 3 to 4 weeks while it's healing.
Here is some information regarding medicine and your wound:
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You can take over-the-counter pain medicine, such as acetaminophen for pain, unless you were given a different pain medicine to use. Talk with your doctor before using this medicine if you have chronic liver or kidney disease, a stomach ulcer or digestive tract bleeding, or you are taking blood-thinner medicine.
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If your doctor prescribed antibiotics, take them as directed. Do not stop taking them just because you feel better. You need to take the full course of antibiotics.
Follow-up care
Follow up with your doctor as advised. Any time there is an injury that causes bleeding, or if the nail was drained, there's a risk of infection. Watch carefully for the signs listed below.
When to contact your doctor
Contact your doctor or get medical care right away if:
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You have increasing redness around the nail.
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You have increasing local pain or swelling.
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Pus is draining from the nail.
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You have a fever of 100.4ºF (38ºC) or higher, or as advised by your doctor.
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