Subungual Hematoma (Black Toenail) 2026 | DPM

Quick answer: Subungual Hematoma Dark Spot Toenail Diagnosis When To Worry is a common nail condition with multiple causes including trauma, fungal infection, biomechanical pressure, and underlying medical conditions. Treatment depends on the cause: trauma resolves as the nail grows out (6-12 months), fungus needs antifungal therapy, and biomechanical issues need shoe and orthotic correction. Call (810) 206-1402.

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

A dark spot under a toenail is common — and usually the result of a subungual hematoma (blood blister beneath the nail) from trauma. Most of the time there’s no cause for alarm. However, a subset of dark nail discolorations represent subungual melanoma — an aggressive form of melanoma that is frequently diagnosed at a late stage because it is dismissed as a bruise. Knowing the difference can be life-saving.

Subungual Hematoma: The Common Cause

A subungual hematoma is a collection of blood beneath the nail plate from disrupted capillaries in the nail bed, typically caused by:

• Acute trauma: stubbing a toe, dropping a heavy object, sports injury
• Repetitive microtrauma: runners whose toes repetitively impact the shoe toe box (runner’s toenail / “black toenail”)
• Ill-fitting footwear causing chronic nail bed pressure

Acute subungual hematomas are painful immediately after trauma — the pressure of blood accumulating under the nail creates intense throbbing pain. The dark discoloration (deep red to purple-black) appears within hours of the injury.

Treatment: Small hematomas (less than 50% of nail surface area) without associated nail fracture can be left to grow out naturally. Large, painful hematomas may be drained by trephination — creating a small hole through the nail plate with a heated cautery device or drill to release the blood and relieve pressure. This is a simple, office-based procedure. Subungual hematomas grow out with the nail over 6–12 months.

Subungual Melanoma: The Rare but Important Diagnosis

Subungual melanoma is a form of acral lentiginous melanoma — a melanoma subtype that develops in areas without sun exposure (palms, soles, nail units). It accounts for approximately 1–3% of all melanomas in Caucasians but is disproportionately common in Asian, African American, and Hispanic populations (up to 30–40% of melanomas in these groups). The great toenail is the most common site.

Distinguishing Features: The ABCDEs of Nail Melanoma

The following features should prompt immediate dermatology or podiatry evaluation:

• A — Age/Race: African American, Asian, or Hispanic patient; age 50–70 years
• B — Brown-Black Band: A longitudinal melanonychia (brown to black vertical streak running the full length of the nail)
• C — Change: Streak that is darkening, widening, or developing irregular borders over time
• D — Digit involved: Thumb or great toe (highest incidence sites for subungual melanoma)
• E — Extension: Hutchinson’s sign — pigmentation extending from under the nail onto the surrounding skin (proximal or lateral nail fold). This is a major red flag for melanoma.
• Single nail: Melanoma typically affects a single nail; benign longitudinal melanonychia from medications, systemic conditions, or nail matrix nevi often affects multiple nails

When Hematoma Can Be Confused with Melanoma

A round, discrete dark spot that moves distally as the nail grows out over weeks to months is consistent with a resolving hematoma. A streak that does NOT move with nail growth and persists or expands over months requires biopsy evaluation. Any nail discoloration with no clear traumatic history warrants evaluation — patients often attribute nail changes to forgotten injuries, delaying diagnosis.

What to Do

Any dark nail discoloration with Hutchinson’s sign, any non-resolving stripe without clear trauma, or any dark streak in a patient from a higher-risk demographic should be promptly evaluated by a podiatrist or dermatologist. Nail matrix biopsy is the definitive diagnostic step. Early-stage subungual melanoma confined to the nail unit is potentially curable with surgical excision; advanced lesions carry poor prognosis.

Frequently Asked Questions

How long does it take a toenail to grow back?

6-12 months for a full big toenail. Smaller toenails 4-6 months. Speed varies with age, circulation, and nutrition.

Will this affect other nails?

Trauma affects only the injured nail. Fungal infection can spread without treatment. Systemic causes affect multiple nails simultaneously.

Should I cover the nail or leave it open?

Cover with a breathable bandage during work or activity. Leave open at night for healing. Keep dry and clean.

What is Foot pain?

Foot pain is a common foot/ankle condition that affects mobility and quality of life. Understanding the underlying cause is the first step in successful treatment. Our podiatrists at Balance Foot & Ankle perform a hands-on biomechanical exam, review your activity history, and use diagnostic imaging when appropriate to identify the root cause—not just treat the symptom. Many patients have been told to “rest and ice” without a deeper diagnostic workup; our approach is different.

Symptoms and warning signs

Common signs of foot pain include pain that worsens with activity, morning stiffness, swelling, tenderness when palpated, and difficulty bearing weight. If you experience sudden severe pain, inability to walk, visible deformity, numbness or color change, contact our office the same day or visit urgent care—these can signal a more serious injury such as a fracture, tendon rupture, or vascular compromise. Diabetics with any foot wound should seek same-day care.

Conservative treatment options

Most cases of foot pain respond to non-surgical care: structured rest, supportive footwear changes, custom orthotics, targeted stretching and strengthening protocols, anti-inflammatory medications when medically appropriate, and in-office procedures such as ultrasound-guided injections. We also offer advanced therapies including MLS laser therapy, EPAT/shockwave, regenerative injections, and image-guided procedures. Treatment is sequenced from least invasive to most invasive, and we explain the rationale at every step.

When is surgery considered?

Surgery is reserved for cases that fail 3-6 months of well-structured conservative care, when there is structural pathology (severe deformity, complete tear, advanced arthritis), or when imaging shows damage that will not heal without intervention. Our surgeons have performed 3,000+ foot and ankle procedures and prioritize minimally-invasive techniques whenever appropriate. We discuss recovery timelines, return-to-activity milestones, and realistic outcome expectations before any procedure is scheduled.

Recovery timeline and prevention

Recovery from foot pain varies based on severity and chosen treatment path. Conservative cases often improve within 4-8 weeks with consistent adherence to the protocol. Post-procedural recovery may range from a few days (in-office procedures) to several months (reconstructive surgery). Long-term prevention involves footwear assessment, activity modification, structured strengthening, and regular check-ins with your podiatrist if you have a history of recurrence. We provide written home-exercise plans and digital follow-up support.

Visit Balance Foot & Ankle — Same-Day Appointments Available

Our podiatry team serves patients throughout Michigan including Howell, Brighton, and Bloomfield Hills. If you’re dealing with heel pain, ingrown toenails, or a foot injury, we have same-day appointment availability.

Related Care at Balance Foot & Ankle

Clinical toenail services at our Howell and Bloomfield Hills offices.

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