If you’ve ever injured your fingernail or toenail, you may have noticed blood pooling under the nail bed’s surface. This bruising is called a subungual hematoma. It’s usually caused by a crushing or stubbing injury. Over time, the blood may turn dark, and the pressure of the hematoma may cause your nail to come off completely (avulsion).

Before that happens, though, you may choose to relieve the pain and pressure by draining the hematoma. In this procedure, also called trephination, a small hole is made into the nail to allow the blood to flow out. Drainage can be performed quickly and relatively painlessly in a doctor’s office or urgent care center.

Here’s what you need to know about subungual hematoma drainage, when you can do it, what happens if you don’t, and when you should see a doctor or healthcare professional.

Doctors recommend draining subungual hematomas when they cause pain or make up 50% or more of the nail. If you’ve also fractured your finger, doctors recommend drainage if the hematoma makes up 25% or more of your nail.

Regardless, you’ll want to head to a doctor within the first 48 hours after your injury for the best results. The blood begins to clot after this amount of time, making drainage difficult.

The amount of time it takes for a hematoma to reabsorb depends on the size of the hematoma. In general, it may take several months for your hematoma to reabsorb or grow out without trephination.

What if your nail falls off? If your fingernail has fallen off because of the pressure of the hematoma, it may take between 4 and 6 months to fully grow back. A toenail may take between 12 and 18 months to grow back. Nails that grow back may have ridges or other abnormalities.

Small hematomas may heal on their own without much issue. You may reduce some of these symptoms for more mild cases by elevating your hand or foot, using a cold compress for pain/swelling, and applying compression to slow the bleeding under the nail.

Larger hematomas may or may not cause issues. Without drainage, you may experience intense pain or other symptoms such as feeling pressure on the nail. The hematoma may change colors from red to purple to dark brown to black. The pressure of the blood underneath the nail’s surface may also cause the nail to fall off partially or completely.

If home measures don’t give you relief, you should contact a doctor for the next steps. Remember that nail drainage can only be performed within the first 2 days after your injury. So, if it’s bothering you, head to your doctor to get help.

Also be sure to contact a doctor if:

You should not attempt to drain your hematoma at home. Using home methods such as a heated pin or paperclip to make a hole in the nail may cause infection from bacteria entering the wound. Infections can often cause much more damage than the simple injury that they stem from.

The process doctors follow to drain subungual hematomas is as follows:

Relief from pain and pressure may be immediate after trephination. That said, you may experience drainage for a couple days after the procedure. This is normal.

Contact a doctor if you experience any symptoms of infection such as fever, warmth at the injury site, pus, or swelling. Other possible risks include loss of your nail or re-accumulation of the hematoma.

Subungual hematomas are common after stubbing or crushing injuries to the fingers or toes. If you experience this type of injury, don’t hesitate to get checked out by a doctor.

Draining the nail is a simple, relatively painless process that can help you feel better, but it needs to be done soon after your injury to be successful. Home drainage methods shouldn’t be attempted, as they are likely to cause pain and infection.

Last medically reviewed on October 6, 2022

Our experts continually monitor the health and wellness space, and we update our articles when new information becomes available.

Carissa Stephens, RN, CCRN, CPN

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