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Black toenail

A black toenail is usually blood trapped under the nail after a knock, a crush or repeated pressure. Small, painless ones often need only ice, elevation and pain relief, and a clinician can drain a painful one. A dark nail with no clear injury should be checked.

Reviewed by Andrew Schox, BSc(Hons) PGradDipPod MPodLast reviewed 27 October 2026 6 min read

Jump to a section
  1. 1. What is a black toenail, and how common is it?
  2. 2. What causes a black toenail, and who gets it?
  3. 3. What does it feel like, and how is it diagnosed?
  4. 4. What can I do first, and what will a podiatrist or doctor do?
  5. 5. What if that isn't enough?
  6. 6. How long does it take to settle, and can I stop it coming back?
  7. 7. When to see a podiatrist

At a glance

  • It's blood trapped under the nail, usually after a knock, a crush or repeated pressure on the toe.
  • Small, painless ones often need no treatment, and ice, keeping the foot raised and pain relief can be enough for minor ones.
  • A painful one can be drained by a trained clinician, so it's best not to try it yourself.
  • A dark nail with no clear injury needs checking, because it isn't always a bruise.
  • The nail can take a while to settle, and nail changes can happen even with good care.

What is a black toenail, and how common is it?

A subungual haematoma (blood trapped under the nail) is a collection of blood beneath a fingernail or toenail, often after a crush or other knock to the nail. The trapped blood raises the pressure under the nail, which causes throbbing pain, and the nail looks dark red to black. It's a common nail injury.

Many people know it as a black toenail or a bruised toenail. Not every dark toenail is blood from an injury, so it's worth getting one checked if you're unsure of the cause.

What causes a black toenail, and who gets it?

Most often it's a single injury: dropping something heavy on your toe, a direct blow or a crush. Repeated small knocks can cause it too, which is why it's seen in long-distance runners and dancers. Badly fitting shoes can also be behind it. It can even build up unnoticed over time, with no one injury you remember. In children, the typical injury is a fingertip caught in a closing door.

Some people need extra care. Blood-thinning medicines and clotting conditions are relevant, so tell your clinician if that's you. If you have diabetes or poor circulation, you may feel less pain and put off getting help, which raises the risk of complications. It's sensible to check that your shoes fit and leave room for your toes, especially if you run.

What does it feel like, and how is it diagnosed?

The usual sign is sudden, throbbing pain after a knock, with the nail turning maroon to black, and sometimes blue-white. One that has been there longer can look purple-black and often isn't tender. A small, painless one usually needs no treatment.

A podiatrist or doctor can diagnose it by asking how it happened and examining the nail, the skin around it, and the circulation, feeling and movement of the toe. They may suggest an X-ray, because a broken bone under the nail is common with these injuries. If the nail seems to have darkened on its own, they'll ask about repeated pressure and consider other causes.

What can I do first, and what will a podiatrist or doctor do?

For a minor one, ice, keeping your foot raised and pain relief are recommended. Wrap the ice in a towel rather than putting it straight on your skin. A pharmacist can advise on pain relief such as paracetamol.

If the pain is moderate to severe, a trained clinician can drain the blood. Draining (trephination) makes a small hole in the nail so the blood can escape, and it usually brings immediate pain relief. It's the typical treatment, and most people need nothing more. It's best to be assessed first rather than draining it yourself, because an X-ray is advised before draining if a fracture is suspected. Afterwards, keep the toe clean and dry.

Draining the blood or removing the nail doesn't seem to change how the nail looks afterwards.

What if that isn't enough?

A larger haematoma, or one where the nail bed may be cut, may need the nail removed and the nail bed repaired. Where the nail itself is intact, that isn't required. A displaced or open fracture, or a badly torn nail bed, needs urgent assessment and repair.

Most of the research is on fingers, so how well it applies to toes is less certain. A clinician will weigh up what suits your toe.

How long does it take to settle, and can I stop it coming back?

Outcomes are generally good, and most people do well after simple drainage. Even with the best treatment, though, the nail can separate, change shape (temporarily or permanently) or become infected. Problems are more likely with an underlying health condition or a more serious injury, and healing can be much slower with diabetes or poor circulation. Nail changes can take time to settle and may not clear quickly.

Wearing shoes that fit, with room for your toes, is sensible. It isn't clear yet that any change in footwear stops one coming back.

When to see a podiatrist

See your GP or a podiatrist the same day if:

  • the pain is severe;
  • the toe or foot is swollen with pus, or has spreading redness, heat or swelling;
  • you have diabetes and a wound, sore, blister or colour change on your foot, including a bruise that hasn't started to heal after a few days;
  • you can't put weight on the foot after the injury, or you think the toe may be broken;
  • it was a severe crush injury, because rarely this can cause dangerous pressure in the toe.

For urgent advice when it isn't an emergency, call healthdirect on 1800 022 222 (24 hours a day), or go to a Medicare Urgent Care Clinic.

See your GP soon if a dark nail has no clear injury behind it, isn't growing out, or keeps coming back. A haematoma can look like a melanoma (a serious skin cancer), so don't assume it's a bruise. Taking dated photos helps track any change.

See a podiatrist or your GP if more than half the nail is involved, or if you have poor circulation or take blood thinners.

Common questions

Will my toenail fall off?

It can happen. The nail can separate or change shape, temporarily or sometimes for good, after bleeding under it, even with good care. If a nail loosens, keep the toe clean and dry and protect it from knocks. A podiatrist can talk through what's likely for your toe.

How long does a black toenail take to grow out?

There's no reliable timeframe, so it's best to be patient. Nail changes can take time to settle and may not be fully back to normal quickly. A podiatrist can look at your toe and give a sense of what to expect, and can check the nail if you're unsure how it's changing.

Further reading

Want to know more? Black toenail on Clindice

Reviewed by Andrew Schox, BSc(Hons) PGradDipPod MPod

Podiatrist

Reviewed 27 October 2026. Next review by 27 October 2027.

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Sources

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This page is general information, not a diagnosis or a treatment plan for you. For advice about your own feet or legs, see a podiatrist or your doctor. In an emergency, call 000.

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