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Black Spots Under Toenail: 5 Causes of Black Toenails

Seeing your toenail turning black is alarming, and a range of issues can cause black spots under the toenail. Find out 5 potential causes in this article.

Read on

Seeing your toenail suddenly or slowly turning black is definitely alarming, but there are a range of issues that can cause black spots under toenail ranging from minor to more severe.

After reading this article, if you are still unsure what could be causing your black spots under toenail, or it is causing you significant distress, you should schedule an appointment with your doctor to get a full assessment of the situation.

Below are 5 things that can lead to your toenails turning black or having black spots.

Also Read: 10 Best Toenail Fungus Avoidance Tips

1. Poor-Fitting Shoes

This one should be easy to identify.

If you wear shoes that are way too tight, or just fit in a strange way that causes your toenail to be constantly hitting the shoe or rubbing the nail constantly - it can damage the toe enough to cause blood to build up underneath giving the nail a black appearance.

Step one here is to get yourself to the shoe store to pick up a well-fitting pair of shoes.

2. Toe or Foot Injury

Any extreme injury to the toenail or foot may lead to blood vessels to break in the area and blood to pool underneath the nail.

Think back to if you really stubbed your toe, dropped something heavy on your foot, or have just been running a lot to train for that marathon, as all of these things may lead to a toe injury that causes your nails to turn black.

This type of nail injury may come along with a feeling of pressure under the nail, and in extreme cases, you may need to see a doctor to let them drill a tiny hole and let some of the blood out.

However, in the case of minor injury which is not causing you much pain, you may be able to treat a toenail injury at home with the RICE technique:

R - Rest the foot. This means to put your marathon training schedule on hold for a few weeks to allow the nail to heal.

I - Ice the toe to help reduce any inflammation and pain that you may be having. This can be done multiple times daily, but try not to ice for longer than 30 minutes at a time.

C - Compress the area to reduce inflammation using a bandage wrapped around the toe. This may help reduce the amount of blood that ends up pooling under the nail.

E - Elevate the affected foot to reduce swelling.

3. Melanoma

The most severe form of skin cancer, melanoma, can occur anywhere you have skin on your body, your toes included.

Melanoma usually appears as a dark brown to black unusually shaped spot, and when it occurs near or under the toenails it can look like a long dark streak through the nail. With melanoma, the surrounding toe skin may take on a darkened appearance as well.

If your black spots under toenail did not come from a direct injury or obvious nail fungus, you will need to see your doctor to ensure you are not dealing with something more serious like melanoma.

If you are diagnosed with melanoma, your doctor will go over the next potential treatment options for removal.

With melanoma, early detection is key! So, don’t brush off unusual dark spots under or around your toenails.

4. Toenail Fungus

A toenail fungus, also known as onychomycosis, is a common nail affliction that can usually be safely removed with prescription therapy over a long period of time.

While most nail fungi appear as yellow to brownish discolorations, sometimes the fungus can appear dark brown to black with the buildup of debris under the nail.

Some signs that you may be dealing with a nail fungus include:

Yellow to brown to black nail discoloration

Thickened nails

Brittle, crumbly, or ragged texture

Changes in nail shape

Foul smell

If all signs are pointing to a nail fungus, you can schedule an appointment with your local doctor for treatment, or have an Online Visit with our U.S. licensed doctors today.

Our Strut Nail Formula is a blend of multiple antifungal medications mixed into a base with a strong driving agent DMSO to make sure the ingredients get through the nail to the root of the fungus.

If you are a good candidate for treatment, your prescription nail fungus treatment can be shipped discreetly to your front door.

5. Certain Medical Conditions

Certain medical conditions have been found to cause one or many toenails turning dark or black.

These conditions may include:


Kidney disorders

Heart disease


You will need to speak with a doctor to make sure that the cause of your black toenails is one of these conditions and not something else like a fungus or melanoma.

If you have diabetes, you will need to see a doctor for anything happening involving your toes or feet, due to diabetics having increased risks of infection and generally worse wound healing.

In general, to help get rid of a black toenail caused by one of these conditions, the root condition would need to be improved.

When to see a doctor for black spots under toenails

Unless you know exactly what caused your toenail to turn black (like, you dropped a hammer on it last weekend), and it is not causing you much discomfort, it is best to have a doctor check out your black toenail to make sure nothing serious is going on.

A toenail fungus is a complicated fungal infection and often will need prescription antifungal medications to clear completely.

Bottom Line: If you don’t know why your nail turned black or you are having a lot of discomfort from the nail - go see a doctor for a diagnosis and treatment.

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