Black Toenail: Causes, Prevention, and Effective Treatments

Black Toenail - Causes, Treatment and Prevention

A black toenail is rarely a cause for serious concern but is usually the result of a minor injury or fungal infection. At first, noticing discoloration under one of your toenails can give you a shock. Probably your first question is “what caused my toenail to turn black?”

Depending on the cause of the blackened toenail, you can use some home remedies to treat the damaged nail naturally. For example, tea tree oil is great for getting rid of nail fungus. Or you can apply a cold compress if the toe and toenail have suffered a trauma. In some cases, if the discoloration under your toenail doesn’t go away you should see a doctor because it can be a sign of melanoma (skin cancer).

In this article, you will find out how to treat and prevent black toenails at home. First of all, let’s examine the various reasons for black toenails.

Causes of Black Toenails

If you are worried about the reason your toenail has turned black, the following information will help you to know the cause of the darkening under your nail.

Toenail fungal infection

A very common reason for having a black toenail is a fungal infection in the toenail (onychomycosis). Fungal infections are very common on the feet because fungi thrive in the dark, damp conditions in your footwear. It is also easy to pick up a toenail fungal infection walking around locker rooms or in swimming pools.

According to doctors from the National Health Service, toenail fungus can cause the nail to turn black, white, green, or yellow. You will also find that as well as the toenail becoming discolored, fungal nail infections are one of the main reasons why toenails thicken and become crumbly. The thick, black toenail may also cause pain if it puts pressure on your toe.1

Injury to toenail

An injury to your toenail will cause your toenail to turn black. The condition is called subungual hematoma, which is basically bleeding under the nail. Along with the black toenail, the injury may also cause swelling, intense pain and throbbing.

Dr. Melinda Ratini on WebMD says that usually, a “crush trauma” like dropping something on your foot or stubbing your toe causes bleeding which results in a bruised toenail. Unless there has been damage to the nail bed or broken bones, you should have nothing to worry about. The toenail will also be tender to touch and painful as blood collects between the nail and the nail bed.2

Dr. Ratini says that a black toenail after an injury will usually fall off and take up to 6 months to regrow.

Repeated toenail trauma

Sometimes it doesn’t take a painful injury for your toenail to become discolored and black. Small repetitive traumas can cause bruising under the toenail making the toenail black. These types of toenail traumas are very common among athletes and runners. Sometimes, a black toenail that athletes have is referred to as “runner’s toe.”

Doctors from the Cleveland Clinic say the toenail gets damaged as it repeatedly and forcefully makes contact with the front of your shoe. This causes small blood blisters to develop under the toenail. In the end, running results in a black toenail that will probably eventually fall off.3


If you have a black toenail or black lines under a toenail without any sign of fungal infection or trauma, then it could be melanoma. Melanoma is a type of skin cancer that develops in the pigments of your skin.

Dermatologist, Dr. Amanda Oakley says that melanoma of the nail bed starts as a dark line the length of the nail. It will gradually become wider and may cause the nail to crack. If the black lines or spots under your nail have been caused by bleeding (and not by cancer) the spots will move and gradually disappear as the nail grows. However, if the spot stays in the same place for many weeks, you should have it examined.4

If you are concerned about any blackened areas under one or more of your toenails, you should see your doctor for a checkup.

Black Toenails – Treatment and Prevention

There are no “quick-fix” methods to treat black toenails. However, there are many effective home remedies that can help to kill off fungal infections and speed up the healing process of an injured toenail.

How to treat toenail fungal infection at home

Tea tree oil for fungal infections

Use tea tree oil to kill off fungal infections that cause black, discolored, and thickened toenails. Tea tree oil antifungal activity is thanks to a compound called terpinen-4-ol. This is effective in treating various fungal and bacterial infections like athlete’s foot, ringworm, acne, and also insect bites.

A study into the antifungal effect on toenail fungal infections found tea tree oil to be just as effective as clotrimazole. Clotrimazole is a pharmaceutical drug used for topical application to get rid of fungal infections. After 6 months of treatment, the tea tree oil cured toenail fungus in just as many patients as clotrimazole.5

How to use:

To get rid of a black toenail caused by fungal infection with tea tree oil, Dr. Weil recommends the following:6

  • Put a few drops of tea tree oil on the end of a cotton swab.
  • “Paint” the tea tree oil on the affected toenail.
  • Continue doing this for around 2 months until the nail no longer has any signs of a fungal infection.

This length of time for treatment is needed because the nail needs time to grow out. Even if you still have some signs of a toenail fungal infections after 2 months, continue persevering as it may take longer to kill off the infection.

Tea tree oil remedy for fungal infections has fewer side effects and is cheaper than many “conventional” antifungal nail treatments.

Snakeroot extract for black toenail fungus

Snakeroot extract (Ageratina pichinchensis) is another effective natural antifungal treatment for curing a black toenail that is a result of fungal infections. Doctors at the Mayo Clinic say that some people have had success in using snake root extract for nail fungus.7

For example, a study on people with mild to moderate nail fungal infections found that within 6 months almost 80% of nail fungal infections were cured. The researchers concluded that snake root extract has “high rates of effectiveness in patients with mild and moderate onychomycosis.”8

You can use snake root extract in a similar way to tea tree oil to destroy fungus causing toenail infections.

You can also find information on how to use apple cider vinegar, hydrogen peroxide and baking soda to treat toenail fungus in my article about natural cures for toenail fungus.

Prevent black toenails – fungal infection

It’s important to prevent fungal infections affecting your feet and toenails. These preventative measures are also important while treating toenail fungus to speed up the healing time.

This is how to prevent black toenails forming due to fungal infections:

  • Keep your feet as clean and as dry as possible.
  • Wear flipflops or waterproof sandals walking around locker rooms or other communal areas.
  • Change your socks or pantyhose daily.
  • Clip toenails straight across to help prevent fungal infections.

How to treat injured black toenail

If your toe has been injured or had a trauma, quick treatment can help to reduce bleeding under the nail and prevent it turning black. In fact, prompt home care for your toenail can also help prevent infections to your toe and speed up the healing process.

Doctors from the WebMD recommend using ice to prevent bruising under the nail. As soon as possible after the nail trauma, this is what you should do:9

  • Put some crushed ice in a sealable plastic bag and wrap in a thin towel.
  • Keep your foot elevated to prevent blood flowing to the injury.
  • Hold the ice pack on for 10-15 minutes, then rest for 5 minutes.
  • Repeat for 2-3 times each session to help prevent your nail turning black.

If the swelling and buildup of blood under your nail is painful, your doctor may drain the blood from under the nail.

Prevent black toenail – injury

If you suffer from black toenails because of repetitive trauma, there are some ways to prevent blackened and bruised toenails.

Doctors from the Cleveland Clinic have published the following advice to help prevent black toenails caused by repeated small injuries:3

  • Wear proper fitting running shoes. Proper athletic footwear should be comfortable and still have some extra space for your toes. This will prevent too much pressure on your toenails that can cause bleeding in the nail bed when you are running.
  • Use silicone toe pads to prevent damaging your toenails when running.
  • Tie your laces properly so that your feet don’t slide in your shoe.

Black Toenail – When to See a Doctor

Generally, the only worry about having a black toenail is that it looks unsightly and may cause embarrassment. However, there are some times when you should contact your doctor for professional medical help.

You should see a doctor for a black toenail in the following circumstances:

  • There are signs of an infection like pus, swelling, and redness in the tissue around the toe and black toenail.
  • The swelling in the toenail causes discomfort and it’s difficult to carry out your daily activities.
  • Black marks or lines appear in the nail and there has been no injury or infection which could have caused this.
  • You don’t like the appearance of the nail and want to have it removed.

If you suffer from diabetes, a weakened immune system, or have circulatory problems, you should always have a qualified podiatrist examine black or damaged toenails. This is to avoid complications that could lead to serious medical problems.

Read my other related articles:
1. Simple and Effective Natural Cures for Toenail Fungus
2. Health Warnings Your Fingernails May Be Sending
3. Home Remedies to Get Rid of Ingrown Toenails
4. Yellow Toenails and Fingernails – Causes and Effective Treatments

Article Sources

  1. NHS. Fungal nail infection.
  2. WebMD. Subungual hematoma.
  3. ClevelandClinic. Tips to protect your toenail.
  4. DermNetNZ. Melanoma of nail unit.
  5. J Fam Pract. 1994 Jun;38(6):601-5.
  6. DrWeil. Nail fungus.
  7. MayoClinic. Nail fungus.
  8. J Ethnopharmacol. 2009 Oct 29;126(1):74-8.
  9. WebMD. Nail problems and injuries.

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