Black or Bruised Toenails: Trauma vs Fungal Discoloration
Black or Bruised Toenails: Trauma vs Fungal Discoloration
By Sylke Bommel · Updated August 2026 · 6 min read
Key Takeaways
- A subungual hematoma, blood trapped under the nail from trauma, is the most common cause of sudden black or purple nail discoloration
- Fungal infections typically cause gradual yellow-brown discoloration with thickening, not sudden purple-black color
- A hematoma migrates outward and grows off with the nail over time; it does not spread to other nails
- A dark streak that appears without injury, widens over time, or involves the skin fold around the nail needs prompt medical evaluation
- When in doubt, especially with no clear injury, see a doctor rather than guessing between trauma and something more serious
What Causes a Black Toenail?
The most common cause of a sudden black or dark purple toenail is a subungual hematoma, blood trapped between the nail plate and nail bed after an injury, like stubbing a toe or dropping something on it.
Other, less common causes of nail discoloration include fungal infection, certain bacterial infections, and, rarely, a pigmented lesion or melanoma, which is why understanding the pattern of discoloration matters.
How to Recognize a Hematoma
A subungual hematoma typically follows a clear injury, causes throbbing pain that eases over the following days, and appears as a reddish to purple-black discoloration that does not blanch, or lighten, when pressed.
Over time, the hematoma stays in place on the nail plate while new, clear nail grows in behind it, so the discoloration visibly migrates toward the tip of the nail and eventually grows off entirely.
How This Differs From Fungal Discoloration
Fungal nail infections typically cause gradual yellow-brown discoloration accompanied by thickening, brittleness, and often crumbling at the edges, developing slowly over weeks to months rather than appearing suddenly.
Unlike a hematoma, fungal discoloration doesn't require an injury to explain it, tends to spread to affect multiple nails over time if untreated, and doesn't migrate outward and grow off the way trapped blood does.
When Dark Nail Discoloration Needs Medical Attention
See a doctor promptly if a dark nail streak or discoloration appears without any clear injury, widens or spreads over time, involves the skin fold around the nail, or affects only a single nail with no other explanation.
These features can indicate subungual melanoma, a rare but serious form of skin cancer that can be mistaken for a bruise or fungal stain, particularly in its early stages. Any dark streak wider than a few millimeters, especially on the big toe or in someone over 50, warrants prompt evaluation.
What to Do About a Bruised Nail
A mild hematoma from a minor bump can usually be left alone to grow out on its own, while a hematoma covering a large portion of the nail with significant throbbing pain may need to be drained by a doctor to relieve pressure.
Trying to drain a hematoma at home is not recommended, since improper technique carries a real risk of infection. If pain is severe or the nail appears to be lifting from the nail bed, see a podiatrist rather than managing it yourself.
If It Turns Out to Be Fungal
If the discoloration follows the gradual, yellow-brown, thickening pattern typical of fungal infection rather than a clear injury and purple-black hematoma color, a formulated antifungal solution is the appropriate next step.
Imperial Feet's Nail Mycosis Solution is formulated to penetrate the nail plate and reach fungus at the nail bed, working best on nails that have been lightly filed back first, consistent with how topical antifungal treatment performs best generally.
No injury = see a doctor
A dark nail streak that appears without a clear injury or widens over time should be evaluated promptly, since it can occasionally indicate something more serious than a bruise
Hematoma vs Fungal: Quick Signs
- ✓Sudden onset after injury, throbbing pain → likely hematoma
- ✓Gradual yellow-brown color, thickening → likely fungal
- ✓Purple-black color that migrates and grows off → likely hematoma
- ✓Spreads to multiple nails over months → likely fungal
- ✓No injury, widening streak, or single nail affected → see a doctor
⚠️ Important: A dark nail streak with no clear injury, that widens over time, or that involves the surrounding skin fold should be evaluated by a doctor promptly to rule out subungual melanoma.
Nail Mycosis Solution
If nail discoloration follows the gradual, yellow-brown fungal pattern rather than a trauma-related bruise, Nail Mycosis Solution is formulated to penetrate the nail plate and reach fungus at the nail bed.
View Nail Mycosis SolutionFrequently Asked Questions
How do I know if my black toenail is a bruise or fungus?
A bruise, or subungual hematoma, typically follows a clear injury and appears as purple-black discoloration that migrates outward and grows off with the nail, while fungal discoloration is usually gradual, yellow-brown, and accompanied by thickening rather than a sudden color change.
Does a bruised toenail need to be drained?
A mild hematoma can often be left to grow out on its own, but a large hematoma with significant throbbing pain may need to be drained by a doctor to relieve pressure; attempting to drain it at home is not recommended due to infection risk.
When should a black toenail be checked by a doctor?
See a doctor if the discoloration appears without a clear injury, widens over time, involves the surrounding skin fold, or affects only one nail with no obvious explanation, since these features can indicate something more serious than a bruise.
Can toenail fungus cause black discoloration?
Occasionally, some fungal infections can cause darker pigmentation, but the classic presentation is gradual yellow-brown discoloration with thickening, which develops over weeks to months rather than appearing suddenly like a bruise.
How long does it take for a bruised toenail to grow out?
Since the discoloration is trapped within the existing nail plate rather than the nail bed itself, it takes as long as the nail needs to fully regrow, often several months for a toenail, gradually moving toward the tip until it's trimmed away.
Clinical Sources
- Piraccini BM, et al. Differential diagnosis of pigmented nail lesions. ScienceDirect, reviewed August 2024.
- Subungual Hematoma: Insights From a Clinical Case Study. PMC12178952.
- Trauma-Associated Pseudo-Hutchinson Sign case report. PMC11769705.
- Nail Melanoma overview. Skin of Color Society, skinofcolorsociety.org.
Related Reading
- How to Get Rid of Toenail Fungus: A Complete Guide
- Ingrown Toenails: Causes, Treatment, and Prevention
- Nail Health: How to Keep Your Toenails Strong and Healthy
Owner, Imperial Feet — Third-Generation Foot Care
Sylke Bommel is the owner and third-generation leader of Imperial Feet, the Dutch professional foot care brand her grandfather founded in 2001. Raised in Aruba and based in Haarlem, just outside Amsterdam, she has led the brand's international expansion for over a decade, growing Imperial Feet from a single Dutch distributor to a professional range used by pedicurists, podiatrists, and pharmacies in more than 20 countries, including the United States.
Editorial note: Sylke writes from the perspective of a foot care brand owner and formulator, not a medical practitioner. Content is educational and does not replace individual medical advice from a qualified foot care professional.
Disclaimer: This article is for informational purposes only and does not replace individual medical advice from a qualified foot care professional. If you have diabetes, poor circulation, or a persistent infection, consult a podiatrist before self-treating.
