Monday, May 20, 2024
FOOT HEALTH Skin and Nail Problems

Black Toenail: 5 Common Causes and Treatment (A Helpful Guide) is a participant in the Amazon Services LLC Associates Program. As an Amazon Associate, I earn from qualifying purchases. Read full Disclosure here.

A black toenail is a common condition that many people experience. Black toenails can be caused by minor injuries or serious underlying medical conditions. They can be unsightly and uncomfortable, but the good news is that most cases can be easily treated. 

In this article, we will explore the 5 common causes of black toenails and the most effective treatments available. 

Causes of Black Toenails

Throughout the day, our feet endure a considerable amount of strain and pressure. Fortunately, our bodies are adept at signaling when something is amiss. 

Toenails are composed of a protein called keratin, which is also present in our skin and hair. 

Typically, toenails are shiny, firm, and white, with a translucent appearance. However, when toenails sustain damage, their color and texture can become altered.

toenail black

1) A Subungal Hematoma of the Toenail Can Cause a Black Toenail

A subungual hematoma is a fancy word for “bruise” underneath the toenail. Sometimes, trauma to the toenail is obvious. 

Say for instance, you dropped a barbell on your toenail. You would naturally notice pain and bruising in the toenail. 

First, you would see red blood underneath the toenail, which would progress to dark brown, and eventually black. If your toenail is black, then the blood has been there for a while. 

However, a lot of times people will develop subungual hematomas without even realizing it. 

If you stub your toe often, you may not even realize that you have developed a subungual hematoma. You may look down at your toenail one day and it may already be black.

Diabetics with numbness in their feet are especially vulnerable to injuring their toes and not realizing it. That’s why it’s so important to check your feet every day. 

Wearing Shoes That Are Too Small Can Also Cause a Subungual Hematoma

Did you know that the majority of people wear shoes that are just too small for their feet?

If your shoes are too tight and narrow, or if your shoe toe box is very shallow and compresses the toenail, then you may likely develop a black toenail. 

Your feet are very unique. Sometimes one foot may be larger than the other. Some days you may notice more swelling in your feet, which may require a larger shoe. 

When buying shoes, make sure you go see your foot doctor or visit your local shoe store to have your feet appropriately measured. 

The way to properly measure your feet is using a Brannock device. “The Brannock device can improve the sizing accuracy of your foot measurement up to 95%-96%.” You can use it to measure your shoe size as well as width. 

If you decide to buy your own Brannock device, you can buy it here.

Here’s a video below by San Luis Podiatry on how to properly use a Brannock device: 

Pro tip: It’s important to get your feet measured at the end of the day when they are the most swollen. Your two feet may measure differently. If they do, go with the larger and wider shoe size when picking shoes. This will ensure that your shoes don’t cause trauma to your toenail. 

If you have children, make sure you measure the sizes of their feet every 3-6 months, as their feet get bigger quickly and thus their shoes should be changed accordingly. 

pointed ballet shoes

Toe Trauma From Activities Can Cause a Subungual Hematoma

If you are a runner, you may notice that you develop black toenails often. 

Subungual hematomas are quite common in runners and sprinters. A black toenail has also been called “a runners toe”.  

That’s because, in runners, repetitive stress occurs to the toenails.

Dancers (especially ballet dancers) are also at risk of developing a black toenail. 

Any sport that causes excess pressure to be placed on the toes can cause a toenail to turn black. 

Related post: Is Your Toe Broken? Here’s Everything You Need To Know

black fungal toenail

2) A Fungal Infection Can Cause a Black Toenail

Toenail Fungus

A fungal infection can cause a toenail to turn black. Typically, when fungal infections penetrate the skin and nails, the toenail becomes thick and yellow. In some cases, the toenail may turn white or look black.

To avoid fungal infections, it’s crucial to refrain from walking barefoot. If you notice any thickening or discoloration of your toenail, it’s vital to inform your doctor immediately so that you can receive appropriate treatment. 

Fungal infections are difficult to treat since they often persist for a long time and may require several months or even years of treatment.

Read more about how to prevent foot fungus from spreading and recurring in a supplemental article here.

psoriasis nail

3) Medical Conditions

Black toenails can be indicative of various health conditions. 

Medical conditions such as psoriasis and kidney failure can lead to toenail discoloration. 

How Does Kidney Disease Affect the Toenails?

Kidney disease is known to decrease filtration in the kidneys, causing a buildup of nitrogen waste products in the body. This buildup can lead to skin and nail changes, including black toenails. 

Therefore, it is essential for people with kidney disease to take care of their feet and monitor any changes that occur.

How Does Psorasis Affect the Toenails?

Psoriasis is a skin condition that affects many people worldwide. In addition to the skin, psoriasis can also impact the nails, causing thickening and ridging. 

One of the telltale signs of psoriasis is the development of “splinter hemorrhages.” These occur when tiny blood vessels along the nail bed are damaged, leading to black toenails. 

If you have psoriasis, it is vital to seek medical attention if you notice any changes in your toenails.

Medications Can Cause the Toenails to Turn Black

In addition to medical conditions, certain medications can also cause toenail discoloration. 

Chemotherapy drugs and some antibiotics, for example, can cause the toenails to turn black. 

Therefore, if you’re taking any new medication and notice changes in your toenails, it is essential to inform your healthcare provider.

melanonychia toenail

4) Melanonychia of the Toenails

Black toenails can be caused by a condition called “melanonychia”. This term refers to the dark discoloration of the nail plate, which is typically brown or black. 

Melanocytes are responsible for producing melanin, and when they produce more melanin than usual, dark discoloration can occur in the nails. 

While anyone can develop melanonychia, it is more common in individuals with darker skin tones.

In most cases, melanonychia is not a cause for concern. However, if you notice progressive worsening pigmentation in the nail, it is essential to seek medical attention. 

Your doctor may recommend a biopsy to rule out any underlying health conditions.

melanoma toenail

5) Melanoma

Although it’s uncommon, a black toenail could be a sign of a more severe condition, such as melanoma, which is a type of skin cancer. 

Melanoma occurs when the pigment-producing cells in the skin called melanocytes grow uncontrollably, leading to the formation of a tumor.

If you notice irregular patches of black discoloration on your toenail that are spreading or pigmentation that extends into the skin adjacent to the toenail, it’s crucial to seek medical attention immediately. 

A Dermatologist or Podiatrist can perform a biopsy to determine if the discoloration is due to melanoma.

Melanomas are aggressive and are a dangerous form of skin cancer. They usually develop slowly and you may not experience any symptoms. 

If you are over the age of 50, have a family history or personal history of melanoma, you may be at higher risk for melanoma

Like other forms of melanoma, if left untreated, cancer can spread to other parts of the body and become very serious. 

It’s important to note that melanoma can be treated successfully if caught early. Therefore, it’s essential to monitor your toenails regularly and seek medical attention if you notice any changes.

What Would the Biopsy Entail?

Your doctor will numb your toe using an injection filled with a local anesthetic. 

Your doctor will then take a punch biopsy needle to obtain a small sample of your nail, nail bed, and nail matrix and send it to the lab.

 You can continue your activities regularly after a punch biopsy. 

Since the biopsy will be obtained from the nail matrix (which is where the nail-creating cells are that are responsible for the growth of the toenail), you may notice that your toenail may grow out slightly deformed afterwards.

Toenail Hematoma vs Melanoma: Which Is It?

Signs of Toenail Hematoma

  • Black or red discoloration under the toenail
  • Pain or discomfort in the affected toe
  • Swelling or inflammation around the toenail
  • Difficulty walking or wearing shoes due to discomfort

Signs of Melanoma

  • Irregular patches of black or dark brown discoloration on the toenail
  • Pigmentation that extends into the surrounding skin
  • Changes in the shape or texture of the toenail, such as thickening or ridges
  • Bleeding or discharge from the toenail
  • Pain or discomfort in the affected toe


Subungual Hematoma

If the hematoma is minor and there are no complications, the doctor may simply recommend applying ice to the affected toe, elevating it, and resting the foot.

However, if the hematoma is more severe and causes a lot of pain, the doctor may opt for a more invasive treatment. 

This can include using a needle to puncture the nail and drain the blood from the hematoma. This procedure is known as trephination and is usually done under local anesthesia.

In some cases, the doctor may also remove a portion or the entire nail if the hematoma is large or if the nail has been severely damaged. 

This can help promote healing and prevent the development of complications such as infections.

Home Remedies

If you have minimal pain in your toe, you can try these home remedies: 

  • Soak your toe in warm water and Epsom salts. This will help relieve some of the discomfort in the toe. 
  • Using a nail clipper, carefully trim away any sharp edges of the nail. If the tip of your toenail is loose, you can trim away the loose edge. 
  • Apply antibiotic ointment to the toe and keep the toe covered using a clean bandage. If you notice any signs of infection in the toe such as a foul odor, redness in the toe, or pus, it is time to contact your doctor. 

What Happens if a Subungual Hematoma Is Untreated?

If a subungual hematoma is left untreated, it can lead to complications such as infection, pain, permanent nail damage, and even loss of the affected nail. 

Fungal Infections

To treat fungal infections, your doctor may recommend a prescription antifungal pill or drops. 

Topical antifungal creams and ointments may also be prescribed, but they are less effective for treating toenail fungus. 

It’s important to follow your doctor’s instructions carefully and complete the full course of treatment to ensure that the infection is completely cleared.


Treatment for melanoma may involve surgical removal of the affected nail and surrounding tissue, as well as radiation therapy or chemotherapy. In some cases, amputation of the toe may be needed. 

Early detection and prompt treatment are key to improving outcomes for patients with melanoma.

When Should You See a Doctor?

Knowing when to see a doctor regarding a black toenail is important for proper diagnosis and treatment. 

Typically, it takes 6 months to a year for a toenail to grow out fully, and if the discoloration is due to a subungual hematoma, it should progress as the nail grows. 

However, if the toenail remains black for several months or the discoloration spreads, it’s crucial to contact your doctor for a biopsy. 

If you have a personal or family history of melanoma, it’s important to take skin cancer seriously and not delay seeking medical attention. 

Contacting your doctor for a biopsy can provide peace of mind and allow for timely treatment if necessary. 

Additionally, if you have a subungual hematoma that is causing significant pain, it’s important to seek medical attention promptly to prevent potential complications.

toenail black causes


In conclusion, black toenails can be caused by a variety of factors, such as trauma, fungal infections, or melanoma. While some cases may not require immediate medical attention, it’s important not to ignore any changes in the color, texture, or shape of your toenails. 

Regularly checking your feet and nails for any signs of discoloration or abnormalities can help you catch potential issues early on and seek treatment promptly.

Related article: Toenail Is Falling Off: Understanding the Causes & Treatments of Toenail Loss


toenail black pin

DISCLAIMER: The information, including but not limited to, text, graphics, images and other material contained on this website are for informational purposes only. No material on this site is intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or another qualified healthcare provider with any questions you may have regarding a medical condition or treatment before undertaking a new health care regimen, and never disregard professional medical advice or delay in seeking it because of something you have read on this website.

Vaishnavi Bawa
Dr. Vaishnavi Bawa is a Podiatrist who specializes in treating foot and ankle pathology. LifesLittleSteps mission is to educate the public about foot health in an easy-to-understand manner using evidence-based medicine.
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