Medically reviewed by Dr. Tom Biernacki, DPM — Board-Certified Podiatric Surgeon — Balance Foot & Ankle, Howell & Bloomfield Hills, MI. Last updated April 2026.

A black toenail — medically a subungual hematoma — is blood pooling under the toenail after trauma, causing the nail to appear dark red, purple, or black. It is one of the most common nail conditions treated by podiatrists and one of the most frequently mismanaged at home. Understanding the cause determines the appropriate treatment: most black toenails from trauma resolve without intervention, but pressure relief may be needed for painful acute hematomas, and any black nail without clear trauma history needs evaluation to exclude subungual melanoma. At Balance Foot & Ankle in Howell and Bloomfield Hills, Michigan, Dr. Tom Biernacki, DPM evaluates all nail discoloration accurately.

Quick Answer: Black Toenail

A black toenail from acute trauma (dropping something on the foot, stubbing the toe) is a subungual hematoma — blood under the nail. Small hematomas (<25% of nail) resolve without treatment. Large, painful acute hematomas (>50% of nail) may benefit from nail trephination (draining the blood) to relieve pressure — ideally within 24–48 hours. Runner’s black toenail from repetitive shoe friction is treated by trimming the nail short and correcting shoe fit. Any black or dark nail that appeared without trauma or is not improving after the nail grows out must be evaluated by a dermatologist or podiatrist to exclude subungual melanoma.

Causes of Black Toenails

Black toenails have several distinct causes with different management approaches:

• Acute traumatic subungual hematoma — Dropping an object on the toe or stubbing; immediate acute blood accumulation; nail may be tender to pressure; nail plate may eventually detach and grow out
• Runner’s black toenail (repetitive microtrauma) — Repeated nail-to-shoe box contact during running; most common in long-distance runners, especially in shoes that are slightly too short or too wide; painless or mildly tender; the 2nd toe (longest in many feet) and 1st toe are most commonly affected
• Sports friction — Soccer, basketball, court sports where the foot slides forward in the shoe; treatment: correct shoe size and lacing
• Toenail fungus with hematoma appearance — Dark discoloration from fungal pigmentation; distinguished from hematoma by chronicity, nail thickening, and absence of trauma
• Subungual melanoma — Malignant melanoma under the toenail; can appear as a dark streak (longitudinal melanonychia) or diffuse pigmentation; does not follow trauma history; must be excluded in any persistent nail darkening without clear cause

Subungual Melanoma: When to Be Concerned

Subungual melanoma is rare but deadly if missed. The hallmark features that should prompt urgent evaluation:

• Dark streak (band) running from the nail base to the tip — longitudinal melanonychia — especially if it is wide (>3mm), irregular, or has multiple colors
• Darkening that spreads from the nail onto the surrounding skin (Hutchinson’s sign) — highly suspicious for melanoma
• Dark nail without any clear traumatic history
• Dark nail that has been present for more than 2–3 nail growth cycles (approximately 12–18 months) without improvement
• Dark nail in skin of color — subungual melanoma is disproportionately common in darker-skinned individuals and is frequently diagnosed late
• Nail that is ulcerated, bleeding, or has a raised mass under it

Treatment of Traumatic Black Toenail

Small hematomas (<25% of nail area): Observation only. The blood will absorb or remain dark as the nail grows out over 6–9 months. No intervention required. Keep the nail trimmed to reduce leverage.

Large, acutely painful hematomas (>50% nail, extreme pressure pain): Nail trephination — creating a small hole through the nail plate with a heated needle or drill to release the pressure. Must be performed within 24–48 hours for maximum benefit. After this window, the blood begins to coagulate and cannot be drained. The procedure provides immediate pressure relief and is essentially painless when performed correctly.

Runner’s black toenail prevention: Fit running shoes with a full thumb’s width of space beyond the longest toe. Tie laces more firmly to prevent forward foot slide. Trim toenails straight across at or just below the tip of the toe. Wear moisture-wicking socks to reduce friction.

What Happens to the Nail After a Black Toenail

After a traumatic subungual hematoma, the nail may detach (onycholysis) from the nail bed over the following 2–4 weeks as the blood beneath separates the nail from its attachment. This is painless in most cases. The nail typically falls off entirely within 2–3 months, and a new nail grows in beneath it over the following 6–9 months. The new nail may be slightly misshapen or ridged initially but typically normalizes. No intervention is needed for nail detachment after trauma unless there is pain, infection, or significant trauma to the nail bed that requires repair.

Warning Signs

• Spreading redness, warmth, or swelling of the toe — possible infection under a detaching nail
• Dark stripe running along the nail without trauma history — urgent evaluation to exclude subungual melanoma
• Extreme pain that is not improving with elevation and ice — possible subungual abscess or underlying fracture
• Diabetic patient with any nail trauma — urgent evaluation due to infection risk

Black Toenail Evaluation in Michigan

Dr. Tom Biernacki, DPM at Balance Foot & Ankle evaluates all nail discoloration including subungual hematoma, melanoma screening, and nail care at both our Howell and Bloomfield Hills locations. Call (810) 206-1402 or book online.

Related Nail Guides

• Toenail Fungus Treatment Guide
• Nail Psoriasis vs. Toenail Fungus
• Toenails Peeling Off
• White Chalky Toenails After Nail Polish
• Best Running Shoes for Foot Problems

Expert Toenail Treatment in Michigan

A black toenail can result from trauma, fungal infection, or other conditions requiring evaluation. Our podiatrists provide accurate diagnosis and appropriate treatment to resolve toenail problems.

Learn About Our Toenail Treatment Services → | Book Your Appointment | Call (810) 206-1402

Clinical References

1. Holzberg M. “Common nail disorders.” Dermatologic Clinics. 2006;24(3):349-354.
2. Rich P. “Nail changes due to diabetes and other endocrinopathies.” Dermatologic Therapy. 2002;15(2):107-110.
3. Daniel CR, Piraccini BM, Tosti A. “The nail and hair in forensic science.” Journal of the American Academy of Dermatology. 2004;50(2):258-261.

Dr. Tom Biernacki, DPM

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.