A bruised fingernail, known medically as a subungual hematoma, is a pool of blood trapped between the nail plate and the nail bed underneath it. Most small ones heal on their own with basic home care: ice, elevation, and over-the-counter pain relief. Larger or more painful ones sometimes need a doctor to drain the trapped blood through a small hole in the nail. The tricky part is knowing which category yours falls into, and recognizing the handful of situations where what looks like a simple bruise actually needs urgent attention.
What Is Actually Happening Under the Nail
When you slam a finger in a door, drop something heavy on it, or catch it during sports, small blood vessels in the nail bed rupture and bleed. Because the nail plate sits right on top like a rigid shield, the blood has nowhere to go. It collects in a dark red, purple, or black patch that you can see through the nail. The pressure from that pooling blood pressing against the sensitive nail bed is what causes the throbbing pain, which can be surprisingly intense for such a small injury.
The nail bed itself is a layer of soft tissue rich in blood vessels and nerve endings. It is responsible for anchoring the nail and feeding nutrients to the growing nail plate. When it is injured, the quality of the repair matters for how the nail looks as it regrows. Proper management of nail bed injuries helps prevent long-term deformities like ridges, splits, or nails that grow back irregularly.1PubMed Central. Nail bed injuries and deformities of nail
Home Treatment for a Minor Bruised Nail
If the bruise is small, pain is manageable, and the finger otherwise looks and moves normally, you can treat it at home. Here is what helps:
- Ice: Apply a cold pack wrapped in a cloth for 15 to 20 minutes at a time during the first day or two. This limits swelling and can reduce bleeding under the nail.
- Elevation: Keep your hand above heart level when you can, especially in the first few hours. Gravity helps slow blood flow to the injured area.
- Pain relief: Ibuprofen or acetaminophen can take the edge off. Ibuprofen also reduces inflammation.
- Protection: A simple bandage or splint keeps the finger from getting bumped again. Avoid activities that put pressure on the nail for a few days.
The dark discoloration will not disappear quickly. As your nail grows out over the following weeks and months, the bruised portion slowly moves toward the tip of the finger and eventually gets trimmed away. A fingernail takes roughly three to six months to grow from base to tip, so you may be looking at a dark patch for a while. That is cosmetic, not dangerous.
When You Should See a Doctor
Not every bruised nail needs medical attention, but certain signs mean you should get the finger looked at rather than toughing it out. The main red flags fall into a few categories:
- Severe or worsening pain: Throbbing that does not respond to ice and over-the-counter painkillers usually means the blood pressure under the nail is high enough to need drainage.
- Large hematoma: If the dark area covers more than about half the nail surface, a clinician should evaluate the finger. The size of the hematoma can signal a more significant nail bed injury underneath.
- Damaged nail plate: If the nail itself is cracked, lifted, or partially torn away, the nail bed beneath may be lacerated and could need repair. When the nail plate is disrupted, exploration of the nail bed is indicated to check for lacerations that should be sutured.2PubMed Central. Approach to nail trauma for primary care physicians
- Deformity or inability to bend the finger: If the fingertip looks crooked or you cannot move it through its full range of motion, there may be an underlying fracture of the small bone at the tip of the finger (the distal phalanx).
- Signs of infection: Increasing redness, warmth, swelling, pus, or red streaks developing in the days after the injury warrant prompt medical evaluation.
A fracture of the distal phalanx sometimes accompanies a subungual hematoma, especially from crushing injuries. If the fracture is displaced or involves the growth region of the nail (the germinal matrix near the base), it may require stabilization and surgical repair rather than simple drainage.2PubMed Central. Approach to nail trauma for primary care physicians
How Doctors Drain a Subungual Hematoma
The standard treatment for a painful subungual hematoma with an intact nail is a procedure called trephination. It sounds more dramatic than it is. A clinician makes a small hole through the nail plate to release the trapped blood. The blood drains out, the pressure drops, and pain relief is usually rapid and significant.3PubMed. Controlled nail trephination for subungual hematoma
There are a few ways to make the hole. One common method uses a heated paperclip or a handheld electrocautery device to melt through the nail plate. Another uses a small drill or an 18-gauge needle rotated between the fingers. The nail plate itself has no nerve endings, so the hole-making part usually causes minimal discomfort. What the person mostly feels is the satisfying release of pressure once the blood starts draining.
The key principle is that when the nail plate is intact and in good position, trephination alone is sufficient. The clinician does not need to remove the entire nail to inspect the bed underneath. This is a meaningful shift from older teaching, which held that large hematomas automatically required nail removal and formal nail bed repair. Research has shown that for hematomas with an intact, undisplaced nail, trephination produces results comparable to more invasive approaches regardless of hematoma size or the presence of a nondisplaced fracture.2PubMed Central. Approach to nail trauma for primary care physicians Nail removal and repair are still indicated when the nail plate itself is disrupted, when a fracture is displaced, or when there is injury to the germinal matrix at the nail base.
The Old “50 Percent Rule” and Why It Is Fading
For years, a common rule of thumb in emergency medicine was that if a subungual hematoma covered more than 50 percent of the nail (or more than 25 percent with an associated fracture), the nail should be removed and the bed formally repaired. This guideline was based on the assumption that a large hematoma implied a serious laceration of the nail bed that needed suturing.
That threshold has been challenged by a growing body of evidence. Studies comparing simple trephination to full nail removal and repair have found no meaningful difference in cosmetic outcomes, complication rates, or infection rates, even for hematomas larger than half the nail and even in the presence of fractures.4PubMed Central. Management of Pediatric Distal Fingertip Injuries: A Systematic Literature Review The intact nail plate acts as its own splint, holding the nail bed in position while it heals. Removing it can actually introduce new risks: more pain, more potential for infection, and disruption of tissue that was aligned under the nail.
This does not mean size does not matter at all. A very large hematoma still warrants professional evaluation because it signals a higher-energy injury. The point is that evaluation and trephination are not the same as automatic nail removal. Your clinician will assess the nail margins, the stability of the nail plate, and whether there is an underlying fracture before deciding on the approach.
Treating Bruised Nails in Children
Fingertip injuries are extremely common in children. Doors, drawers, and car doors are the usual culprits. The same general principles apply as in adults, but the evidence in children is particularly strong that conservative management works well.
A direct comparison of children treated with nail removal and bed repair versus simple trephination or observation found no notable difference in outcomes regardless of hematoma size, fracture presence, injury mechanism, or age. The only major difference was cost: charges were roughly four times higher for the group that underwent formal nail removal and repair.5PubMed. Comparison of nail bed repair versus nail trephination for subungual hematomas in children A more recent study confirmed this pattern, finding infection rates of about 3 percent in the nail-repair group, 0 percent in the trephination group, and about 3 percent in the group managed conservatively, with no significant difference between them.6PubMed Central. Reevaluating Pediatric Nailbed Injuries: Are We Overtreating Simple Cases?
For smaller hematomas (less than half the nail) with no fracture in a child, expert consensus supports a straightforward approach: no antibiotics, no nail removal, no formal surgical drainage, and bandage changes at home.7PubMed Central. It’s Just a Fingertip! Yet Controversy Exists: Standardizing a Treatment Pathway for Pediatric Fingertip Injuries Larger hematomas still generate some debate among specialists about whether trephination or watchful waiting is better, but the overall trend is toward less invasive treatment when the nail and nail margins look intact.
If your child’s nail is cracked, partially detached, or the fingertip looks deformed, those situations do warrant a medical visit. But a kid with a throbbing, dark-colored nail that is otherwise intact and in good position can often be managed at home after a straightforward assessment.
A Safety Warning About Acrylic Nails
If you wear acrylic or gel nail enhancements, there is a specific hazard worth knowing about. When an electrocautery device (which uses heat) is used to trephinate through an acrylic nail, the acrylic material can ignite. A study testing this found that more than 40 percent of acrylic nails caught fire when exposed to electrocautery trephination.8PubMed Central. Up in Flames: The Safety of Electrocautery Trephination of Subungual Hematomas with Acrylic Nails
This does not mean you cannot get a subungual hematoma drained if you have acrylics. It means you should tell the clinician about the enhancement so they can choose a different method, such as a needle or drill, that does not involve heat. If the acrylic nail needs to be removed before the procedure, that is a minor inconvenience compared to a potential burn. The takeaway is simple: mention it before the provider starts the procedure.
When a Dark Nail Is Not a Bruise
Most of the time, a dark discoloration under a fingernail after an injury is exactly what it looks like: trapped blood. But there are situations where a dark streak or patch under the nail is something else entirely, and the distinction matters.
Subungual melanoma is a rare but serious form of skin cancer that can appear as a dark band or discoloration under the nail. It accounts for a small fraction of all melanomas, but it tends to be diagnosed later because people assume the dark color is a bruise or a fungal infection. The key differences: a subungual hematoma usually has a clear history of trauma, appears suddenly, and grows out with the nail over months. Melanoma tends to appear without a clear injury, forms a longitudinal (lengthwise) streak rather than a round blotch, and does not grow out or change position as the nail grows. Irregular pigment patterns, such as lines of varying thickness or color, are a concerning feature. One study found that irregular matrix patterns were present in nearly 90 percent of early subungual melanomas compared to about 22 percent of benign pigmented lesions.9PubMed Central. Intraoperative Nail Matrix Assessment in Longitudinal Melanonychia
Another warning sign is pigment that extends from under the nail onto the surrounding skin of the cuticle or fingertip, sometimes called Hutchinson’s sign. If you have a dark streak under a nail that you cannot connect to an injury, or if a discoloration persists beyond the time it should take the nail to grow out (six months for a fingernail is a reasonable benchmark), see a dermatologist. People with darker skin tones are more likely to develop benign longitudinal pigmented bands on nails, which are harmless, so the evaluation is about distinguishing the common from the rare rather than assuming the worst.
What Recovery Looks Like
After a bruised nail, whether treated at home or drained by a doctor, the timeline follows the nail’s growth cycle. Fingernails grow at roughly three to four millimeters per month. A bruise near the base of the nail will be visible for months as the darkened portion slowly advances toward the free edge. During this time, the nail may feel slightly different in texture or look uneven, but these cosmetic irregularities are temporary in most cases.
In more severe injuries, especially those where the nail bed was lacerated and required repair, the regrown nail may have permanent ridges, splits, or a slightly different shape. Reconstruction of a badly damaged nail bed can be done with grafts or microsurgical techniques, but these are reserved for significant tissue loss rather than routine bruises.1PubMed Central. Nail bed injuries and deformities of nail
Sometimes the entire nail falls off after a bad bruise. This looks alarming but is not usually an emergency. The nail bed underneath will look pink, raw, and tender. Keep it clean, covered with a non-stick bandage, and protected from bumps. A new nail will begin growing from the base within a few weeks, though it takes several months to fully replace the old one. During the regrowth period, the area is more sensitive than usual, so a protective bandage or finger cover during physical activities can save you a lot of wincing.
One thing that catches people off guard: even after the blood is drained and the pain resolves, the nail may still fall off weeks later. The hematoma sometimes separates the nail plate from the bed enough that it eventually loosens. As long as the new nail is growing in normally underneath, this is part of the healing process rather than a setback. If the new nail comes in with a persistent split running its full length, or if the nail does not appear to be regrowing at all after two to three months, a follow-up visit is reasonable to check for damage to the growth matrix.
Toenails and How They Differ
Everything discussed above applies to toenails as well, with a couple of practical differences. Toenails grow more slowly than fingernails, at roughly half the rate, so a bruised toenail can take a year or more to fully grow out. Runners and hikers are particularly prone to subungual hematomas on the big toe from repetitive micro-trauma, where the toe pushes against the front of the shoe stride after stride. These “runner’s toe” bruises often develop without a single clear injury event.
The treatment principles are the same: small and painless means watch and wait, large and painful means get it drained. One difference is that toenails handle repeated stress differently. A single bruised fingernail from a door slam usually heals cleanly once the nail grows out. A toenail bruised by ill-fitting shoes will keep reinjuring unless you address the footwear. Shoes with enough room in the toe box, properly trimmed nails, and moisture-wicking socks reduce the chance of recurrence. For runners logging serious mileage, accepting a dark toenail as part of the sport is surprisingly common, but a toenail that is throbbing or lifting still deserves the same drainage consideration as a finger.