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Black toenail: trauma or fungus? How to tell the difference

4 min · Dr. Romina Orsetti


In brief

  • A black nail is often a subungual haematoma from trauma, not a fungus.
  • A knock or tight shoes can cause bleeding under the nail.
  • At home: protect it, don’t tear it, keep it clean and dry.
  • If it appears without trauma or doesn’t improve, have it assessed.

A toenail turning dark is alarming, but in most cases it’s a trauma. Let’s look at how to recognise it and what to do.

Trauma or fungus: how to tell them apart?

A black nail is often a subungual haematoma: blood pools under the nail after a knock, a fall or because of shoes that are too tight (typical in runners). A fungus, on the other hand, tends to give a more yellow-brown colour, with thickened and crumbling nails. Sometimes a trauma can also lead to onycholysis, that is the detachment of the nail from the bed.

Telling them apart with certainty is not easy with the naked eye: it is the podiatrist, with a clinical eye, who identifies the real cause.

What to do at home?

  • Don’t tear off the nail, even if it is partly lifted.
  • Protect it with a plaster and keep it clean and dry.
  • Wear comfortable shoes that don’t press on it.
  • Keep the nails short and cut straight across.
See a podiatrist or doctor if the nail turns dark without any obvious trauma, if there is intense pain, swelling, or if the mark changes shape and does not improve. Recognising it in time prevents complications.

Frequently asked questions

Is a black nail always a fungus?
No, it is often a bruise from trauma. Only the podiatrist can tell trauma, fungus or other causes apart with certainty.
If it’s coming off, what do I do?
Don’t tear it off: protect it with a plaster, keep it clean and dry and have it assessed by the podiatrist.
When should I worry?
If it appears without obvious trauma, changes shape or doesn’t improve over time: a professional assessment is needed.

Concerned about your feet? Let’s talk

An assessment with a podiatrist catches the problem early and prevents complications. Prevention is better than cure: book in Osimo or Villa Musone di Loreto.