A subungual hematoma is blood under the nail. It can occur when your finger or toe is hit or crushed. It 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 he or she doesn'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.
The following guidelines will help you care for your wound at home:
Apply an ice pack (ice cubes in a plastic bag, wrapped in a thin towel) 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 goes away.
If the nail was drained:
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.
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.
If the nail was removed:
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.
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 non-stick 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.
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:
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 healthcare provider before using this medicine if you have chronic liver or kidney disease. Also talk with your provider if you have had a stomach ulcer or digestive tract bleeding, or you are taking blood-thinner medicine.
If you were given antibiotics, take them until they are used up. It's important to finish the antibiotics even if the wound looks better. This will ensure the infection has cleared.
Follow up with your doctor, or as advised. Any time there is an injury that causes bleeding, or if the nail was drained, there is a risk for infection. Watch carefully for the signs listed below.
Call your doctor right away if any of these occur:
Increasing redness around the nail
Increasing local pain or swelling
Pus draining from the nail
Fever of 100.4ºF (38ºC) or higher, or as directed by your healthcare provider
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