Top 5 causes of black toenails and how to avoid them

Having a black toenail may not seem like a big deal, but it can lead to complications.

Having a black toenail may not seem like a big deal, but it can lead to complications.

Photo credit: Fotosearch

What you need to know:

  • If you notice a change in your nails, such as a black line, see your doctor for an evaluation.
  • Black toenails are often harmless but could signify a serious condition.
  • Therefore, early diagnosis and treatment are important for the best possible outcome.


For many people, toenails are an afterthought. You might give them a cursory glance when getting ready for bed or slip on a pair of sandals, but they do not usually warrant much attention except when they get too long or stub your toe.

However, toenails can tell a lot about your overall health. For example, black toenails are often caused by trauma to the nail, such as from running or kicking a ball.

They can also be caused by severe conditions, such as melanoma.

In this article, discover the potential causes of black toenails and how to avoid them.

Fungal infection

Toenails are susceptible to all sorts of infections and problems. One of the more common toenail problems is a fungal infection. A fungal infection of the toenails is also called onychomycosis.

This infection usually starts as a white or yellow spot on the nail. The nail may become discoloured, thickened, and brittle as the condition progresses. The nails may also separate from the nail bed.

Fungal infections of the toenails are often caused by wearing tight shoes or walking barefoot in public places. To avoid a fungal infection of the toenails, keep the feet clean and dry. Avoid sharing towels, socks, and shoes, as it is a contagious infection.

Wearing socks and shoes that fit well will prevent a toenail fungal infection. If you think you have a toenail fungal infection, see your doctor for treatment.

Melanoma

Melanoma is a type of skin cancer that can also occur in the nails. The melanoma of the nail is also called subungual melanoma. This type of melanoma usually starts as a brown or black line under the nail.

While melanoma is a serious type of cancer, it is rare. If you have a black line under your nail that does not go away, see your doctor for evaluation.

Trauma

One of the most common causes of black toenails is trauma. This can occur from running, kicking a ball, or dropping something on the toe. As a result, the nail may become bruised and discoloured.

Wearing too tight or ill-fitting shoes can also cause trauma to the toenails. Therefore, to avoid black toenails from trauma, wear well-fitting shoes.

Most black toenails caused by trauma will eventually grow out, and the nail will return to its normal colour.

Underlying medical conditions

Some underlying medical conditions can cause black toenails. These include diabetes, anaemia, psoriasis, or heart diseases. If you have any of these conditions, it is important to see your doctor regularly.

Black toenails can also be a side effect of certain medications. If you take medication and develop black toenails, talk to your doctor about the potential side effects.

Pigmentation

In some cases, black toenails are caused by a change in pigmentation. Melanonychia is a condition in which the nails become darker. This is more common in people with darker skin. If you notice that your toenails are suddenly darker than usual, it is important to see your doctor for an evaluation.

Black toenails complications

Having a black toenail may not seem like a big deal, but it can lead to complications. If the toenail is left untreated, it can become infected. The infection can spread to other nails or even to the bone.

The nails may come off completely, which can be extremely painful.

General tips to prevent black toenails

  • Wear well-fitting shoes
  • Avoid tight shoes
  • Keep the feet clean and dry
  • Avoid sharing towels, socks, and shoes
  • Pay attention to any changes in your nails