If you’re here because you’re dealing with a bruised fingernail, I can relate: One casual Saturday years ago, I was getting out of the car for a much-needed shopping trip with friends and completely smashed my thumbnail in the car door. When I looked down at my finger, I saw lots of blood and a huge crack across my entire nail. For the next 30 minutes, my friends and I raced around the mall looking for a Band-Aid and some Advil (Note: I’ve kept a first aid kit in my car ever since).
After the bleeding finally stopped, I was left with a cracked and bruised fingernail. My first inclination was to cover up the ugly wound with a gel manicure. (Yes, that’s my vanity showing.) But it turns out, that is the worst thing to do.
What that experience taught me is that I have a lot of questions about what to do when I’ve injured a fingernail. I know I’m not the first person to slam a finger in a car door or jam it in a window, so I took my questions to the professionals to get all the answers, from basic first aid to the right way to cover up a bruised fingernail or other nail mishap. Here’s what you need to know.
What causes nail bruising?
Like the bruises you get on any part of your body, nail bruising happens when blunt force crushes the small blood vessels under your skin, per U.S. National Library of Medicine. Most fingernail injuries affect the nail plate (the hard part of the nail that grows out), which can crack and potentially fall off, and the nail bed (the skin underneath the nail plate), which can bleed and bruise. So when we’re discussing a nail bruise, we’re really talking about a nail plate bruise.
That said, what you might assume is a nail bruise because of the purple or black color might actually be blood, since the same kind of trauma that causes bruising can cause bleeding too. The official name for this is a subungual hematoma, according to the American Osteopathic College of Dermatology. That pretty much just means a blood blister under the nail.
What should I do if I bruise my fingernail?
When the injury first happens, you can take care of any immediate first aid needs. Basic wound care applies here: Put pressure on the area to slow the bleeding if there is any, clean the wound with soap and water, apply a bandage, and take an analgesic to help with pain if needed. You can also ice your finger if you’ve got swelling in the area, dermatologist Ted Lain, M.D., tells SELF.
As you do all this, you should also assess the extent of the damage and whether or not a trip to the doctor is necessary. Speaking of…
When should I see a doctor?
There are a few things to look out for when it comes to deciding if you should see a doctor right after you injure your fingernail. Some signs include:
Lack of blood flow: Press on a portion of the nail or finger that is not injured. If the area turns white and then turns pink within seconds when you release the pressure, you’ve got good capillary refill. That means blood is still flowing. If not, it’s a good idea to get it checked out.
Loss of sensation: You should also touch the tip of your finger to make sure you still have feeling in the area. “As long as you can feel everything, you probably don’t have any nerve damage,” says Dr. Lain.
Unusual colors in your fingertip: You also want to make sure the skin at the tip of the finger isn’t blue or blanched white—unusual colors are a sign you need to see a doctor.
A lot of blood under your nail bed: Because large subungual hematomas increase the risk of your fingernail falling off, doctors will often drain accumulated blood by drilling a small hole in the nail plate. In Dr. Lain’s clinical experience, blood that encompasses more than 50 percent of your nail is a good sign you should hit up a doctor, but there are no official recommendations. You can play it safe and have a smaller subungual hematoma drained too. The key is to get it done within 24 hours, before the blood coagulates.
Injury to your nail matrix: This is the tissue at the base of your nail where nail growth happens. Since damage to the nail matrix could cause your nail to grow out strangely for the rest of your life, you should let a professional evaluate how serious it is just in case. “If the pressure can be released, then we can feasibly help to control any damage that might happen to the nail matrix,” says Dr. Lain.
If you’re clear of the above signs, you’re likely good to skip the doctor and let the bruise heal up on its own. As for a cracked nail, you’ll have to wait for the damage to grow out. (Fun fact: Fingernails grow an average of 3.47 millimeters a month according to one 2010 study published in the Journal of the European Academy of Dermatology and Venereology.)
All that said, in the days following the injury, you should also be on the lookout for signs of infection.
What are the signs of a fingernail infection?
“If there is any pus, if it becomes really red and hot after the fact, or there is a lot of swelling, it’s a sign of infection,” dermatologist Mona Gohara, M.D., tells SELF. “If it’s green, that’s another sign that there is bacteria in there.” There might also be persistent pain that just doesn’t wane. These symptoms are all signs you need to see a doctor. Make an appointment with a dermatologist, primary care physician, or at an urgent care center to get the wound drained and get a prescription for antibiotics.
If you see red streaks on your hand or forearm or you feel feverish or nauseated, it could be much more serious. These are signs that the infection has spread to the bloodstream, which can lead to sepsis. “Sepsis is extremely serious, and anyone seeing the infection worsening with the spread to the hand should seek care at an E.R.,” says Dr. Lain.
What should I do if my fingernail starts falling off (or falls off completely)?
Yes, your fingernail falling off is a thing that can happen, so it’s good to be prepared. After an acute trauma, your nail may turn black and seem like it’s barely hanging on. Please, please, don’t pull it off. You can cut it down, but let the injury grow out on its own. “Leave it alone, because there is new nail growing underneath,” says Dr. Lain. “The new nail will push up the old nail, and it will come off when it’s ready.”
Once the fingernail falls off, it’s a good idea to protect the sensitive skin of the nail bed with a Band-Aid. “If you leave it open to the air, it can get very dry and very cracked, and if it gets traumatized, it can affect how the nail grows,” says Dr. Lain.
In some cases, like if the nail bed is infected, the doctor might have to remove the nail by force. This procedure is called a nail evulsion: First, they numb up your finger with a local numbing treatment. Then the doctor uses special tools to lift the nail on each side and peel the plate away from the nail bed. (Kind of sounds like something out of a horror movie, right?)
Can I get a manicure with a bruised fingernail?
Now, here’s what I really wanted to know: Can I cover a cracked or bruised fingernail with pretty polish while it’s healing? The answer is yes—with a few precautions.
Dr. Lain recommends first coating the nail with a layer of nail hardener to help protect the nail plate, and Dr. Gohara says nail polish is totally fine if there is just a crack in the nail (once the bleeding has stopped and the injury has had some time to heal, of course).
That said, you should put a pause on your gel manicure habit. “It is not the application of the gel, or the product itself, but rather the removal process that concerns me,” says Dr. Lain. “Gel polish is commonly removed incorrectly, leading to a compromise of the nail’s integrity or worsening of underlying damage.”
Above all, both derms say to avoid the nail salon. “If somebody is using scissors and cutting, you can introduce bacteria or fungus, because the nail has already been compromised,” says Dr. Gohara. It’s best to stick to DIY manicures until the nail has grown out. Luckily, we’re avoiding nail salons right now anyway, right?
Related:
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I Tried 5 Hacks to Stop Biting My Nails and Only 1 Made a Difference
This Manicure Box Makes Doing My Own Nails Easy and Fun