Black and Traumatized Nails

 

A black or blue nail often draws attention and causes concern. In the vast majority of cases, it is a subungual hematoma caused by an impact, repeated friction, or shoes that are too tight. More rarely, the dark discoloration may indicate a deep fungal infection or a nail imbalance requiring appropriate care. Athletes, runners, and people who spend all day on their feet: black nails are a common everyday issue that can be treated. 

At PODERM®, each treatment has been formulated to work deep within the traumatized nail, not just on the surface. We have carefully selected targeted active ingredients in our products to strengthen the nail matrix, promote healthy regrowth, and protect the nail while it regenerates.

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Why does my nail turn black?

A nail that turns black can have several causes. It is important to identify the cause before choosing the treatment.

The most common external causes

  • Direct trauma: a violent impact causes a subungual haematoma (accumulation of blood between the nail and the nail bed)
  • Repeated friction in shoes that are too tight or too short (running, hiking, contact sports)
  • Prolonged wear of dark nail polish without a protective base coat (superficial staining of keratin)
  • Manual work or professions exposing the hands to repeated impacts

Internal causes

  • Nail fungus (onychomycosis): the nail can turn black when the fungus is very deep
  • Iron or vitamin B12 deficiency (the nail may develop dark spots)
  • Nail psoriasis in less frequent cases
  • Subungual melanoma: a rare cause but one that warrants medical consultation if the blackening is not related to an impact

If in doubt, we recommend consulting a podiatrist or qualified healthcare professional.

Black toenail: specific causes

Toenails turn black more often than fingernails, as they undergo significant mechanical stress daily: body weight, closed shoes, endurance sports.

The main causes of black toenails are:

  • Repeated friction is the number one cause among athletes. The big toe is most exposed. The nail turns blue then black over outings, without particular pain at first.
  • Black and thick nail: when a toenail is both black AND thick, fungal infection must be ruled out. Without treatment, the nail can progressively detach from the nail bed.
  • Ill-fitting shoes (too short, too rigid, or pointed) compress the nail with every step and cause repeated micro-traumas even without an identifiable impact.

Is a black nail a sign of a serious illness?

In the vast majority of cases, no. A black nail after an impact or friction is benign and resolves over time. However, certain signs should prompt you to see a doctor:

  • Black nail without identifiable trauma that does not disappear after 2 to 3 months
  • Longitudinal black streak (melanonychia) that progressively widens: possible subungual melanoma
  • Black nail + pus + intense pain: bacterial infection, medical emergency
  • Several nails turning black simultaneously without obvious mechanical cause

Black nail or fungal infection: how to tell the difference?

A haematoma and a fungal infection can look visually similar, but they are not treated the same way.

How to recognise a subungual haematoma:

  • The nail turns black rapidly after an identifiable impact
  • The colour is uniform, dark red to black, under the nail
  • Slight pressure may be painful in the first few days
  • The colour moves towards the free edge as the nail grows

How to recognise a deep fungal infection:

  • The blackening progresses from a corner or the free edge, without impact
  • The nail thickens and becomes brittle
  • A slight odour may appear
  • The texture changes, the nail may partially detach

How to treat a black nail?

If the nail is black following an impact or trauma:

  • Apply a strengthening serum twice a day on the nail and its surroundings
  • Protect the weakened nail with a protective cap if the nail is at risk of detaching
  • Avoid any additional pressure: adapt your footwear, reduce impacts
  • Be patient: full regrowth takes 6 months (fingernails) to 12 months (toenails)

If the nail is black and you suspect a fungal infection:

  • Use a tea tree-based antifungal serum or polish for 3 to 6 months
  • Do not cut the nail too short (risk of spreading)
  • If resistant or in doubt, consult a podiatrist

If the nail starts to detach:

  • Do not pull it off: a silicone cap holds the nail in place and protects the nail bed
  • Continue the strengthening treatment to support the underlying regrowth

How to prevent black nails?
  • Choose shoes with half a centimetre of space between the end of the foot and the toe cap
  • Cut your nails regularly and straight (avoid rounded corners that catch)
  • Wear technical moisture-wicking socks during sporting activities
  • Apply a strengthening serum as a preventive measure if you practise a sport with repeated impacts
  • Dry your feet carefully between the toes after showering to prevent fungal infection
  • Always apply a base coat before a dark polish to prevent pigment deposits

Our best tips for healthy nails
  • Identify the cause before choosing the treatment: impact, fungus or other
  • Do not pull off the detached nail: protect it and let it grow back naturally
  • Act early: the sooner treatment is started after the trauma, the better the regrowth
  • Be patient: a traumatised nail takes several months to return to its normal appearance
  • Maintain a routine with a strengthening serum even after visible healing

Our top tips for healthy nails

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The strengthening serum for dark nails is specially formulated to reinforce and revitalize darkened nails. Dark nails often appear dull and fragile, requiring special care to restore their natural shine. Regular application of a strengthening serum for dark nails helps improve their texture and prevent breakage.

This serum penetrates deeply into the nail matrix to nourish and strengthen its structure. By incorporating this strengthening serum into your routine, you provide your nails with lasting protection against external aggressors.

For optimal results, use the strengthening serum for dark nails as part of a regular care routine. This product not only enhances the appearance of dark nails but also maintains their long-term health. Integrating this serum into your daily regimen ensures stronger, more radiant nails.

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