Why is my toenail turning black

Nail discoloration

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Checked by Prof. Dr. Wolf-Ingo Worret • Dermatologist

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Most of the time, nail discoloration is completely harmless. However, they can also be an indication of diseases.

What is nail discoloration?
Nail discoloration is the term used to describe changes in the color of the horn structure of the fingernails or toenails.

The nails consist of one Horn plate and protect the sensitive fingertips and toes. Usually the nails appear translucent pink.

Nail discoloration: causes

Nail discoloration can numerous causes to have. Various skin diseases, internal diseases or infections with bacteria or fungi are possible for this. The nail discoloration can look very different depending on the underlying causes.

It is therefore best to leave out the possible causes in the case of nail discoloration from a dermatologist clarify. Only your doctor can determine for sure whether nail discoloration is harmless or needs treatment.

Yellow and green nail discoloration

Yellow and green nail discoloration are common Chemicals innail polishorNail hardener traced back. You can also use it as a Side effect of certain drugs occur or a sequence of Fungal diseases or infections with bacteria be.

White discoloration of the nails (leukonychia)

White discoloration of the nails (leukonychia) can have a variety of causes. Sometimes the exact leaves Form of whitening Conclusions about the causes to:

  • Small white dotson the nails (Leukonychia punctata): Small white dots on the nails are common. They are usually caused by injuries, for example when the nail or its root (nail matrix) is crushed. This can be the case, for example, especially on the big toe if you wear shoes that are too tight. White spots or spots on the nail are usually harmless. They are seen more often after infectious diseases.
  • Whiteningof the whole nail(Leukonychia totalis): A whitening of the whole nail is congenital in rare cases. Then all toenails and fingernails are white as chalk.
  • Cloudy white nails (frosted glass nails): Cloudy-white nails can occur with cirrhosis of the liver, and less often with heart failure (weak heart muscle).
  • White horizontal stripes (Leukonychia striata): In most cases, white horizontal stripes are the result of bruising the nail, e.g. in a car door. Manicure injuries (such as nail bed injuries) can also be a cause. However, white horizontal stripes on the nails can also indicate heavy metal poisoning (e.g. with arsenic or thallium) or severe metabolic disorders (e.g. Pellagra). Occasionally, white horizontal stripes appear on the nails with febrile infections (such as scarlet fever).

Also a Nail fungus (Onychomycosis) can be one white or yellow discoloration of the nails cause. However, symptoms of nail fungus usually persist. The affected nails are then not only discolored, but also look, for example, thickened, rough and crumbly.

Brown and (blue) black discoloration of the nails

Dark discoloration of the nails is often caused by bruises (hematomas) after one injuryfor example with a hammer or by crushing it in a door. In many cases, however, if someone has a bruise under the nail, they cannot remember how it happened.

There may also be an infection with one Nail fungus (Onychomycosis). Molds in particular are a possible cause of dark nail discoloration.

Uneven brownish black greenish nails can cause Mixed infections of the nails, for example when the nail is infected with bacteria such as Pseudomonas and a fungus at the same time.

At a brown-black spot or brown-black vertical stripes (so-called Melanonychia striata) under the nail plate it can be harmless birthmark (Mole) or possibly cancer - for example a so-called subungual melanoma (black skin cancer).

Other possible causes for brown-black nails are:

Nail discoloration: diagnosis

In the case of nail discoloration, the dermatologist can often already through the typical appearance Make a diagnosis of the altered nails. The exact shape (e.g. spots, stripes) and shade of the discoloration, a possibly also changed nail shape and other reported complaints can indicate certain causes.

If a nail infection with fungi or bacteria is suspected, the dermatologist will take smears and tissue samples (biopsy) and have them examined under the microscope. If necessary, he can also create a pathogen culture. If there could be an internal disease that manifests itself in nail discoloration, further examinations are necessary for the diagnosis (e.g. blood tests, ultrasound examination).

Nail discoloration: treatment

How to treat nail discoloration depends on the underlying cause. However, treatment is not always necessary. For example, nail discoloration caused by pressure (e.g. in tight shoes) or the use of nail polish will grow out of its own accord over time. For other causes, medication is sometimes necessary to treat the nail changes.

Small white spots (leukonychia punctata) or white horizontal stripes on the nails (leukonychia striata) that are the result of an injury do not need treatment. They grow out again on their own.

If the nail discoloration has other causes, drugs that act locally or throughout the body may be used for therapy. In the case of bacterial nail infections, for example, antibiotics may be necessary, in the case of nail fungus so-called antimycotics.

If there is an internal disease behind the nail discoloration (e.g. cirrhosis of the liver or ulcerative colitis), therapy for the underlying disease is necessary.

Malignant tumors under the nail plate, such as melanoma (black skin cancer), must be surgically removed by the doctor.

What can you do yourself?

You can prevent some nail discoloration:

  • Be sure to, matching shoes to wear. Shoes that are too tight can lead to nail discoloration over time - especially on the big toe.
  • If you are prone to yellow nails from nail polish or nail hardener: always use one Base coatthat protects the nails.
  • If your nails are already discolored from the use of nail polish or nail hardener: leave them off Discoloration will grow out and do not use nail polish or nail hardener during this time. Then you should always use a base coat.

Online information from Altmeyer's encyclopedia: www.enzyklopaedie-dermatologie.de (accessed: July 18, 2019)

Online information from the Pschyrembel: www.pschyrembel.de (accessed: July 18, 2019)

Moll, I .: Dermatology. Thieme, Stuttgart 2016

Haneke, E .: Eye diagnosis - nail changes. Online information from Thieme: www.thieme.de (as of: 8/22/2014)

Sterry, W., et al .: Dermatology Checklist. Thieme, Stuttgart 2010

Plewig, G., et al .: Braun-Falco’s Dermatology, Venereology and Allergology. Springer, Berlin Heidelberg 2012

Altmeyer, P .: Dermatological differential diagnosis. Springer, Berlin Heidelberg 2007

Altmeyer, P .: Therapielexikon dermatology and allergology. Springer, Berlin Heidelberg 2005

Dirschka, T., et al .: Clinical Guide Dermatology. Urban & Fischer, Munich 2003

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Last content check:18.07.2019
Last change: 18.07.2019