Why Is My Toenail Black?

This article was reviewed by Dr. Emilija Ashtalkoska on August 22nd, 2018. Products listed therein are not intended to diagnose, treat, cure, or prevent any disease or health condition.


It is terrifying to look down at your feet and see a black toenail. You may freak out and wonder, is this serious? Is it nail fungus? Should I be concerned?

Do not worry! Below we are going to outline the most commons reasons why people get a black toenail, or black spots underneath their toenails.

Is It Nail Fungus?

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Nail fungus is a disease that affects over 30 million people worldwide. It can cause the nail or area around the nail to emit a foul odor, cause pain, and turn various shades of colors, including black.

Other common symptoms include thinning or thickening of the nail, or discharging fluids, a condition known as weeping.

Onychia and Paronychia, the conditions that cause weeping nails, generally start with soreness and inflammation around the nail, so be on the lookout for this as well.

Nail fungus can be contracted from a variety of places such as pools, nail salons, saunas, or even just walking around barefoot. It can also spread from athlete’s foot (tinea pedis) to infecting the nail, causing it to eventually turn black.

If you believe you have contracted nail fungus, head to our treatment recommendation list and starting treating your nail fungus today.

Unfortunately, nail fungus is highly contagious and will not heal on its own without treatment, so it is in your best interest to start treating the affliction as quickly as possible.

Are You A Runner?

black spot under nail

High endurance, repetitive running is one of the most common sources of black nails.

This will generally appear shortly after repetitive, intense workouts in shoes that do not fit quite right. In mild cases, the nail will appear to have small black and blue dots underneath the nail.

Generally, these are painless and do not require any intervention. Make sure you wear proper fitting running shoes and wait for the nail to grow out over the next 6-12 months.

In more severe cases, large black and bloody blisters can appear under the nail and can cause issues. In some instances, the blister can displace the nail from the nail bed, causing the sufferer extreme pain as it detaches either partially or fully.

This will cause the nail to fall out and a new healthy nail to grow back in within a year.

If you are experiencing a large black spot with any detachment, see your doctor immediately so they can make a proper diagnosis. They may need to file down part of the dead nail to allow the new one to grow in properly.

For most people, a black spot under the nail as a result of running is not a major concern at all. Simply acquire some better fitting running shoes and give your body enough time to heal.

Trauma To The Nail

Trauma to the nail is another major source of black spots. This is known as subungual hematoma. Did you recently slam your toe in a doorstop, or viciously stub your toe?

If so, the blood vessels in your nail beds have most likely ruptured and flooded your nail bed with blood, causing pain and coloring the nail a blackish red. Symptoms of trauma to the nail include:

  • Pain and soreness in the nail
  • A “throbbing” sensation caused by the build up of blood
  • Part or all of the nail falling off

In many instances, light trauma to the nail will heal on its own. However, if the discoloration or throbbing does not go away, see your local podiatrist. They will be able to drain the blood, thus relieving the pain and discoloring.

Skin Pigmentation

For some people, discoloration has to do with their skin tone. This is most often the case with patients of color. Sometimes, pigmentation simply changes over time.

Usually, if this happens, it happens symmetrically, not just one toe. In some instances, it will also occur underneath your fingernails.

Generally, this form of discoloration is completely harmless, but it is recommended that you see your doctor just in case.

Note About Black Toenails

It must be mentioned that if the toenail is black because of an infection, that means that whatever is causing the discoloration is already deep in the nail and whoever has a black toenail must visit a doctor, and will most likely be given prescription medication, both oral and topical.


There are a variety of reasons why someone can develop a black spot underneath their nails.

We also recommend consulting a medical professional before starting any treatment, especially if you have diabetes because this can further complicate issues with feet and black spots.

Hopefully, this article shined some light on some of the most common issues that cause black spots.

1 thought on “<span class="dojodigital_toggle_title">Why Is My Toenail Black?</span>”

  1. I dropped a weight on my toenail and the next day it was all black and blood. Thanks for the article. Hope it clears up soon.

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