How to Get Rid of a Black Fingernail

Most black fingernails are subungual hematomas, which is a clinical way of saying trapped blood under the nail plate, almost always from some kind of blow or crush injury. The blood pools, the pressure builds, and the nail turns a deep purple-brown or black that can look alarming. Getting rid of it depends on how much it hurts: mild cases grow out on their own over weeks to months, while painful ones need a small hole drilled through the nail to release the pressure. The trickier question is whether a black nail that showed up without obvious trauma is really a hematoma at all, or something else entirely.

What Actually Happens Under the Nail

When you slam a finger in a door, drop something heavy on it, or catch it the wrong way during sports, tiny blood vessels in the nail bed rupture. Blood leaks into the tight space between the nail bed and the hard nail plate above it. Because there is almost no room to expand, even a small amount of blood creates visible discoloration and significant pressure. The nail bed changes color to brown or black, and the discoloration can appear immediately or develop over several hours after the injury.¹ The most recognizable symptom is sudden, throbbing pain driven by that blood pressing outward against a nail that will not give.²

The intensity of the pain tends to track the size of the hematoma. A small bruise under one corner of the nail may ache for a day and then become more of a cosmetic nuisance. A large hematoma that covers most of the nail bed can be genuinely excruciating because the pressure has nowhere to go. In either case, the blood itself is not dangerous. The question is whether the pressure is tolerable and whether the structures underneath, like the nail bed and the bone at the fingertip, are intact.

Managing a Mild Black Nail at Home

If the pain is manageable and the nail is not lifting off or cracked, you can usually let the hematoma resolve on its own. The trapped blood will slowly be reabsorbed or pushed forward as the nail grows, eventually reaching the free edge where you trim it away. A few things help during the process:

• Ice and elevation: In the first day or two, icing the finger for 15 to 20 minutes at a time and keeping your hand elevated reduces swelling and slows further bleeding into the space.
• Over-the-counter pain relief: Ibuprofen or acetaminophen can take the edge off the throbbing. Some clinicians suggest avoiding aspirin early on because it thins the blood, which could worsen the pooling.
• Protect the nail: A loose bandage or finger splint keeps the injured nail from catching on things. Repeated bumps to an already-bruised nail bed will extend the pain and could crack the plate.

One thing you should not do is try to drain the blood yourself with a heated needle or paperclip. The idea circulates widely online, but heating a metal instrument and pressing it through the nail carries real risk of thermal injury to the nail bed or introducing bacteria into a space that is otherwise sealed and sterile.³ If the pressure is bad enough that you are considering poking a hole in your nail, it is bad enough to see a doctor who can do it properly.

How Doctors Drain a Subungual Hematoma

The standard treatment for a painful subungual hematoma is a procedure called nail trephination. A clinician creates a small hole through the nail plate to let the trapped blood escape, which relieves the pressure almost immediately. This can be done with a heated wire cautery device, a small drill designed specifically for the purpose, or sometimes a large-gauge needle. The key is controlled penetration through the nail plate without punching into the soft nail bed below.⁴

The procedure sounds worse than it is. The nail plate itself has no nerve endings, so drilling through it is painless. Patients typically report substantial pain relief within hours of drainage. In a prospective study that followed nearly 50 patients for an average of about ten months, every patient reported relief after trephination, and no infections, bone infections, or significant nail deformities occurred, regardless of hematoma size or whether there was an underlying fracture at the fingertip.⁵ That same study found that the average time for the nail to grow back was about four months, though it ranged widely from person to person.

An older school of thought held that large hematomas or those accompanied by a fracture required removing the entire nail and surgically repairing the nail bed underneath. The trephination evidence has largely moved practice away from that approach. Simple drainage works well for uncomplicated hematomas, and nail removal carries its own recovery burden.⁵ That said, if the nail is badly shattered or the nail bed is visibly lacerated through a crack, a doctor will usually want to examine and possibly repair the bed directly, which does mean removing the nail.

How Long Before Your Nail Looks Normal

Fingernails grow at roughly three to four millimeters per month. A black nail from a hematoma needs to grow out entirely before the discoloration is gone, which usually means three to six months depending on which finger it is (thumbs grow more slowly) and your individual growth rate. The darkened section gradually migrates toward the tip as new, clean nail grows in behind it. You will notice a clear demarcation line between the healthy pink nail near the cuticle and the dark section moving outward.

During this period the nail may look rough, ridged, or slightly thickened. That is normal. The nail matrix, the tissue at the base that produces the nail plate, was disrupted by the injury, and it takes time to resume producing a smooth, even nail. Proper management of the initial injury helps prevent lasting deformity. If the nail bed was significantly damaged and not repaired, the new nail may grow in with a permanent ridge or split.⁶ In most simple hematoma cases, though, the nail eventually returns to its pre-injury appearance.

If you are impatient with the cosmetic aspect, a coat of dark or opaque nail polish can conceal the discoloration while it grows out. Just avoid anything that traps moisture against a compromised nail, since that creates conditions friendly to fungal or bacterial infection.

Black Nails Without a Clear Injury

Not every black fingernail comes with a memorable moment of slamming it in something. Repeated low-grade trauma can produce the same result without a single dramatic event. People who work with vibrating power tools like pneumatic drills or chainsaws, those who do heavy manual lifting, and workers in occupations involving repetitive friction on the fingertips can develop nail thickening, brittleness, and discoloration over time.⁷ Musicians who play stringed instruments, climbers, and even people who type aggressively for hours a day sometimes develop darkened nails from cumulative microtrauma they never consciously registered.

Fungal infections are another common culprit. Onychomycosis, a fungal infection of the nail, can turn nails yellow, brown, or even black as the fungus colonizes the nail bed and produces pigmented byproducts. The nail often thickens and becomes crumbly at the same time. Unlike a hematoma, which is usually confined to one nail and appears relatively suddenly, fungal infections tend to progress slowly and may affect multiple nails.

Bacterial infection can also darken a nail. Pseudomonas aeruginosa, a common environmental bacterium, produces pigments that turn the nail green or black. This is sometimes called green nail syndrome and is more common in people whose nails spend a lot of time wet, such as healthcare workers who wash their hands frequently, dishwashers, or people with artificial nails that trap moisture.⁸ Treatment typically requires an oral antibiotic rather than waiting for the discoloration to grow out.

Certain medications can also cause nail darkening as a side effect. Chemotherapy drugs are well known for this, but some antibiotics, antimalarials, and antiretroviral medications can produce the same change. If your nails darkened after starting a new medication, mention it to your prescribing doctor. The discoloration usually reverses after the drug is discontinued.

When a Dark Nail Might Be Melanoma

This is the scenario that worries people most, and rightly so. Subungual melanoma, a type of skin cancer that arises in the nail bed, can present as a dark streak or patch under the nail. It is uncommon relative to hematomas and fungal infections, but it is serious, and delayed diagnosis worsens outcomes significantly. The challenge is that early subungual melanoma can look surprisingly similar to a benign bruise or pigmented streak.

A few features help distinguish melanoma from harmless causes. Melanoma tends to produce a longitudinal streak of pigment, a dark line running from the base of the nail toward the tip, rather than a broad uniform patch. Under magnification, the pigmented lines in melanoma are irregular in their color, thickness, spacing, and alignment. In one study examining nail pigmentation under dermatoscopy, irregular patterns of brown to black lines were strongly associated with melanoma compared to all other diagnoses.⁹ Benign causes like a hematoma or a mole under the nail tend to produce more uniform, evenly spaced patterns.

Another warning sign is the Hutchinson sign, where dark pigment extends beyond the nail plate onto the surrounding cuticle or skin folds. This finding has a close association with subungual melanoma, and biopsy is strongly recommended whenever it appears, although it is not a perfect indicator. False positives exist, especially in children.¹⁰

As a practical rule, see a dermatologist about any dark nail discoloration that did not follow an obvious injury, that appeared on only one nail, or that is changing in size or shape over weeks. A hematoma does not grow; it moves forward with the nail and eventually disappears. A melanoma streak stays at the base and widens. If a presumptive diagnosis like fungal infection is treated but the discoloration does not resolve, or if features are progressing, biopsy is the definitive next step.¹¹

Sorting Out What You Are Dealing With

The biggest practical question for someone staring at a black fingernail is whether they need to do anything at all or whether they need to do something urgently. Here is a quick way to think through it:

• Clear trauma, tolerable pain: You jammed it, it hurts, but you can function. Ice it, protect it, let it grow out. The dark color may take months to fully disappear, but no medical intervention is needed.
• Clear trauma, severe throbbing: The pressure is intense and not improving. See a doctor or urgent care clinic for trephination. The procedure takes minutes and provides fast relief.
• No obvious trauma, gradual onset: Think fungal or bacterial infection, medication side effect, or repeated microtrauma you may not have noticed. See your primary care doctor or a dermatologist for evaluation. Fungal cultures and a visual exam usually sort this out.
• No trauma, a dark streak that is new or changing: This needs prompt evaluation by a dermatologist. The concern is melanoma, and earlier detection matters enormously for outcomes.

Dermatoscopy, where a clinician examines the nail under magnified, polarized light, is a valuable tool for sorting benign from concerning pigmentation. The pattern of lines, their regularity, the presence of blood residue versus true melanin pigment, and the involvement of the surrounding skin all guide the assessment. Pigmented streaks caused by benign activation of melanocytes in the nail matrix, such as from trauma or inflammation, produce continuous longitudinal lines, while subungual hemorrhage tends to create more diffuse, patchy discoloration.¹²

Artificial Nails, Gel Polish, and Nail Darkening

People who regularly wear acrylic or gel nails sometimes discover a darkened nail underneath when the artificial layer is removed. Artificial nails create a sealed environment that can trap moisture between the fake nail and the natural one. That warm, damp space is ideal for bacterial colonization, particularly by Pseudomonas, which produces pigment that stains the nail green or black. The staining itself is superficial and will grow out, but the underlying infection needs treatment.¹³

Gel and acrylic products can also cause allergic contact dermatitis from acrylate chemicals, which may lead to nail bed inflammation, lifting, and secondary discoloration. If you notice darkening, pain, or swelling around your nails after getting them done, remove the artificial product and let the nail breathe. Reapplying layers over an already-irritated nail just prolongs the problem. A dermatologist can help distinguish between bacterial infection, allergic reaction, and traumatic damage from overly aggressive filing during the application process.

Preventing Black Nails in the First Place

For the most common cause, blunt trauma, the prevention advice is straightforward if unglamorous: wear gloves. Work gloves when doing manual labor, sport-specific gloves when appropriate, and general caution around heavy objects and closing doors. Runners and hikers who get black toenails from shoes that are too tight or from downhill pressure can often fix the problem with properly fitted footwear and moisture-wicking socks. The same principle applies to fingers in some sports: batting gloves, cycling gloves, and climbing tape all reduce the cumulative microtrauma that leads to bruised nail beds.

For occupational causes, the evidence points to vibrating tools and repetitive friction as significant contributors to nail damage.⁷ Anti-vibration gloves and taking regular breaks can reduce the cumulative load on your fingernails. If your work involves prolonged water exposure, drying your hands thoroughly and applying a barrier cream helps prevent the moisture-related infections that darken nails.

For people who get gel or acrylic manicures, giving your nails periodic breaks between applications and choosing a technician who does not file the nail plate aggressively reduces the risk of both mechanical damage and trapped-moisture infections. Watching for early signs of greenish discoloration under the artificial nail and removing the product promptly if it appears can keep a minor bacterial issue from becoming a stubborn stain.