Subungual hematoma is the medical term for bleeding and bruising under the fingernail or toenail.

The condition is also referred to as runner’s toe, tennis toe, or a blood blister under the nail. Read on to learn about possible causes and treatments.

A subungual hematoma is usually the result of some kind of injury to the blood vessels under the nail bed. For example, blood vessels can break and leak blood into the area underneath the nail when a door slams on a finger or a heavy object crushes a toe.

It can also occur when a person repeatedly jams their toes into the toe box of a too-tight shoe. This is especially true when the person wearing the ill-fitting shoe engages in sports with a lot of stop-and-start action, as in tennis, soccer, or basketball.

A subungual hematoma can also happen to runners and hikers, especially those who often run or hike downhill.

When space is tight in the front of a shoe, there’s undue pressure on the blood vessels in the toes. This can cause the blood vessels to break and bleed under the nail.

According to the American Osteopathic College of Dermatology (AOCD), the first symptom of a subungual hematoma is throbbing pain in the nail area, thanks to the pressure of blood pooling under the nail bed.

The second symptom is the discoloration of the nail. What starts out as a reddish purple will eventually turn dark brown and black as the blood clots. Nail discoloration can be a symptom of other conditions as well. Learn more about toenail discoloration.

With a subungual hematoma, the pain typically goes away in a few days. The nail itself will take longer to recover.

The discolored nail will eventually grow out — or in some cases, it may fall off or need to be removed — and be replaced by a new, healthy one.

It could take anywhere from 4 to 6 months for a fingernail to grow out or 12 to 18 months for a toenail, according to the American Academy of Dermatology.

A doctor can often diagnose a subungual hematoma based on looking at the nail and any recent trauma you report. For example, if you have the symptoms above and recently whacked your finger with a hammer, your doctor will likely diagnose subungual hematoma.

Your doctor may also X-ray the finger or toe to see whether there’s any fracture associated with the injury.

Many subungual hematomas can be cared for at home.

To reduce swelling, the AOCD recommends elevating the affected hand or foot and icing the area. To do this, wrap ice in a cloth or towel, or create your own cold compress. Applying ice to skin directly can cause damage.

Do not ice an injury for more than 20 minutes at a time.

Over-the-counter (OTC) pain medications can also relieve discomfort, and some will even help reduce inflammation.

For severe symptoms

You may need medical treatment if your symptoms are intense or persist beyond a couple of days.

To relieve pressure and pain, a doctor may perform a procedure called nail trephination. It’s a typically painless procedure. The doctor makes a small hole in the nail where the blood is pooled, allowing it to drain.

Your doctor may do this with a sterile needle or even a sterilized paper clip, which requires skill and should not be attempted at home. They may also use a laser.

Once the pressure is relieved, most people’s pain goes away immediately. If the nail is badly damaged, your doctor will also remove the nail. The damaged nail will most likely fall off on its own if your doctor does not remove it.

Whether your nail is drained or not, it’s important to watch for signs of infection. If you notice any of the following, seek immediate medical attention:

  • fever
  • the nail feeling warm to the touch
  • red streaks
  • pus draining from the nail

Melanoma is a serious form of skin cancer that can cause skin — including the skin under the nails — to become discolored and occasionally bleed.

Melanoma of the nail bed is rare. According to the National Institutes of Health, more than 1.2 million people in the United States had melanoma in 2018. A 2018 study states that just 1.5 to 2.5 percent of all melanomas are subungual melanomas.

However, subungual melanomas tend to get diagnosed later and therefore are more likely to be life threatening.

To determine whether your nail discoloration and bleeding are due to a subungual melanoma or hematoma, your doctor will primarily focus on whether you’ve had a recent injury to your nail or you engage in a sport such as running or tennis.

With a hematoma, pooling of blood in the nail bed usually occurs within a few days of a crushing injury. In contrast to melanoma, nail discoloration from hematoma will gradually clear as the nail heals.

As the nail heals from a subungual hematoma, a transverse groove may form across its surface. Your doctor will look for these and other signs when determining the cause of blood in your nail bed.

Some subungual hematomas — such as the kind that occur when you smash your finger in a door — are just unfortunate accidents and thus hard to prevent. Others, especially those that involve the toes, are easier to avoid.

Here are some overall tips:

  • Wear properly fitting shoes. There are many issues associated with wearing too-tight shoes.
  • If you’re playing soccer or tennis, try to play on natural surfaces such as grass or clay. They’re more forgiving surfaces that will help reduce the friction between the shoe and foot.
  • If you work in construction or in a warehouse, protect your feet from crushing injuries as much as possible with heavy work boots or steel-toed shoes. Foot care is extremely important if you work on your feet all day.
  • Try buddy taping, if your doctor recommends it. In buddy taping, the problematic toe is taped to the toe next to it, reducing friction. If your doctor has not mentioned buddy taping, check with them first before trying it on your own. Buddy taping is not advised for people with peripheral arterial disease and some people with diabetes.

In most cases, a subungual hematoma looks worse than it is. Your nail may throb and turn various shades of blue, purple, and brown. It may even fall off. However, you can often manage a subungual hematoma with self-care and OTC pain relievers.

If the pain is unrelenting, you can have a simple procedure to drain the blood and relieve pressure underneath the nail. The procedure needs to be done by a skilled medical professional. Monitor the nail bed for signs of infection, regardless of whether the nail is also removed.

Once a new nail replaces the old, there’s no need for further treatment or any kind of medical follow-up.