Why Your Toenails Keep Turning Black
Why Your Toenails Keep Turning Black
It can be alarming to look down and see a black toenail. Sometimes it’s painless, other times it throbs with every step. Either way, it’s a sign something’s not quite right.
Black toenails are more common than you might think—and not just for runners or athletes. Understanding the cause is the first step to getting your nails back to a healthy, natural color.
The Most Common Causes of Black Toenails
1. Injury or Trauma
A sudden hit—like stubbing your toe or dropping something on it—can cause bleeding under the nail (called a subungual hematoma). The trapped blood makes the nail look dark purple, brown, or black.
Symptoms: Pain, swelling, tenderness, or pressure under the nail.
Tip: If pain is severe, see a podiatrist quickly to relieve the pressure.
2. Repeated Pressure from Shoes
Tight or ill-fitting shoes can press against your toenail with every step, especially during exercise. Over time, the repeated friction causes bruising under the nail.
Common in: Runners, hikers, and people who spend long hours on their feet.
3. Fungal Infections
Certain fungal infections can discolor nails, turning them yellow, brown, or even black as the infection spreads.
Clues: Thickened nails, crumbling edges, or a foul odor.
4. Underlying Medical Conditions
In rare cases, black toenails can signal more serious issues like melanoma (a type of skin cancer) or blood circulation problems. These require immediate medical attention.
When to See a Podiatrist
You should get a black toenail checked if:
The discoloration lasts more than a few weeks.
You have significant pain or swelling.
You don’t remember injuring your toe.
The nail changes shape, thickens, or lifts from the skin.
A podiatrist can determine if the cause is harmless or something that needs treatment right away.
Treatment Options
For injuries: Draining trapped blood, trimming damaged nails, or removing loose nail portions.
For fungal infections: Prescription antifungal medication, laser therapy, or nail reconstruction.
For chronic pressure: Custom orthotics or shoe recommendations to prevent repeat damage.
Preventing Black Toenails
Wear shoes with enough toe room.
Trim nails straight across—don’t cut them too short.
Wear moisture-wicking socks to prevent fungus.
Replace old or worn shoes regularly.
Black toenails aren’t just a cosmetic issue—they’re your body’s way of signaling something’s off. Whether it’s an injury, fungus, or something more serious, getting the right diagnosis means you can treat it properly and keep your nails healthy.
