Medically Reviewed | Dr. Tom Biernacki, DPM | Board-Certified Podiatric Surgeon | Balance Foot & Ankle, Michigan
Quick Answer:
Quick Answer: A subungual hematoma — blood pooling under the toenail — is caused by direct trauma (dropping an object on the toe) or repetitive microtrauma (runner’s toenail from downhill running in tight shoes). Painful hematomas occupying more than 50% of the nail area benefit from trephination — a simple in-office procedure using a heated needle to create a drainage hole, immediately relieving pressure and pain. X-rays are taken to exclude underlying phalangeal fracture. Nail loss commonly follows but regrowth occurs over 6–18 months. Dr. Tom Biernacki treats nail bed injuries in Michigan with rapid in-office procedures.
Black Toenail: When Blood Under the Nail Needs Attention
A subungual hematoma — blood accumulating in the space between the toenail and the nail bed — is one of the most painful acute toenail injuries. The rigid nail plate prevents the hematoma from expanding, creating intense pressure that produces severe throbbing pain disproportionate to the apparent external injury.
Subungual hematomas occur in two distinct patterns: acute traumatic hematoma from a direct blow (a heavy object dropped on the toe, a forceful kick, or a door-slamming incident) and repetitive microtrauma hematoma from long-distance running — the so-called “runner’s toe” or “runner’s black nail” that develops from the toenail repetitively striking the front of the shoe interior during downhill running or high-mileage training.
When to See a Podiatrist for a Black Toenail
Not every subungual hematoma requires professional treatment. Small hematomas involving less than 25% of the nail area, with minimal pain, can be monitored at home and allowed to grow out with the nail. However, prompt professional evaluation is warranted when:
The hematoma involves more than 50% of the nail surface area — the pain is typically severe enough to require trephination. The injury resulted from significant trauma — an underlying distal phalangeal fracture must be excluded with X-ray. The toe is significantly swollen, warm, or shows signs of infection. The hematoma persists after the acute phase without nail regrowth — melanoma and subungual melanoma (a serious condition) must be excluded for persistent dark nail discoloration without clear traumatic history.
Treatment: Trephination and Nail Bed Management
Trephination — The treatment of choice for painful subungual hematomas involving more than 50% of the nail. Using a heated electrocautery tip or a sterile needle, a small hole is created through the nail plate, allowing the accumulated blood to drain and immediately releasing the painful pressure. The procedure is virtually painless (the nail itself has no sensation), takes seconds to perform, and provides dramatic immediate pain relief.
Nail removal — Required when the nail plate is partially or completely avulsed (torn away) from the nail bed, or when nail bed laceration repair is needed. Nail bed lacerations should be repaired with fine absorbable suture under digital nerve block to optimize nail bed healing and subsequent nail regrowth quality.
Fracture management — Underlying distal phalanx fractures are common with significant toe trauma. Most are treated conservatively with buddy taping and rigid-soled shoe for 3–4 weeks. Displaced or open fractures (when the nail bed laceration communicates with the fracture — an open fracture) require thorough wound irrigation and antibiotic coverage.
Prevention for runners — Runner’s black nails are prevented by ensuring shoes are one-half size larger than street shoe size (accommodates foot swelling during runs), keeping toenails trimmed short, lacing shoes to prevent forward foot slide, and avoiding steep downhill racing without appropriate footwear adjustments.
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✅ Pros / Benefits
- Trephination provides immediate dramatic pain relief for large subungual hematomas
- X-ray excludes underlying phalangeal fracture in traumatic cases
- Nail regrowth occurs completely over 6–18 months with proper protection
- Runners can prevent recurrence with shoe sizing and sock modifications
❌ Cons / Risks
- Nail loss commonly follows significant subungual hematoma — nail regrowth takes up to 18 months
- Persistent dark nail discoloration without clear trauma history warrants biopsy to exclude melanoma
- Open fractures communicating with nail bed lacerations require urgent antibiotic management
Dr. Tom Biernacki’s Recommendation
Subungual hematomas are one of the most satisfying acute treatments I provide — the patient comes in with extreme throbbing toe pain, I perform a 10-second trephination procedure, and they leave with essentially complete pain relief. The contrast is remarkable. The most important thing I always do is get an X-ray to make sure there’s no underlying fracture — because a fracture changes the management, especially if the nail bed is disrupted (which makes it an open fracture requiring careful wound care). If your black toenail is pulsating with pain, don’t wait — come in same day.
— Dr. Tom Biernacki, DPM | Board-Certified Podiatric Surgeon | Balance Foot & Ankle
Frequently Asked Questions
Should I drain a black toenail at home?
Small hematomas with minimal pain can be observed. But draining a toenail at home with a needle risks introducing infection into the sterile nail bed space. For significant pain, professional trephination is safe, reliable, and provides immediate relief. Please do not attempt home drainage for large or painful hematomas.
Will my toenail fall off after a black toenail?
Yes — toenails often fall off after a significant subungual hematoma as the nail bed heals and a new nail grows in from the matrix. This is a normal part of the healing process. The new nail grows in over 6–18 months. Protecting the toe with a hard-soled shoe or toe cap during the regrowth phase prevents discomfort.
How is a subungual hematoma different from a fungal toenail?
Subungual hematoma is blood under the nail — usually dark red, purple, or black, associated with trauma or running, and located at a specific part of the nail. Fungal toenail (onychomycosis) is infection of the nail plate — producing thickened, crumbling, yellowed, or white discoloration that is not related to trauma. Any persistent nail discoloration without clear traumatic history should be professionally evaluated.
Can a subungual hematoma be serious?
Most subungual hematomas are minor nail injuries that heal without complication. The key serious concerns are: underlying fracture (especially open fracture with nail bed disruption); infection (particularly in diabetic patients); and persistent dark nail discoloration without clear trauma history, which requires biopsy to exclude subungual melanoma.
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Dr. Tom Biernacki, DPM is a double board-certified podiatrist and foot & ankle surgeon at Balance Foot & Ankle Specialists in Southeast Michigan. With over a decade of clinical experience, he specializes in heel pain, bunions, diabetic foot care, sports injuries, and minimally invasive surgery. Dr. Biernacki is a member of the APMA and ACFAS, and his patient education content on MichiganFootDoctors.com and YouTube has reached over one million views.
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