What Causes Black Toenails and How Do You Treat Them?

blackened toenail.

Are you worried about the blackening of your toenails seen in the image above? Okay, take a deep breath and listen. If you don’t feel any pain or see any bad signs aside from the discolouration, there’s a great chance you’ll be fine so you can relax now.

However, if there’s more to it than the unsightly black colour, you might need to seek professional advice and treatment for your black toenails as soon as possible.

But before we go deep into that, here are a few reasons for the discolouration of your toenails. 

What causes toenails to turn black?

Toenails can turn black for a variety of reasons. Some common causes of black toenails include:

  • Trauma
  • Fungal infection
  • Melanoma

Here’s a deeper dive into each one of them. 


Have you ever stubbed your toes against heavy furniture like a door or dining table? Don’t be surprised if your nails start to blacken!

This kind of trauma to the toenail is probably the most common reason your toenail is blackening. But aside from stubbing your toes, the toenail can be traumatized in a variety of ways, such as:

  • by wearing shoes that are too tight or too loose
  • by squeezing or slamming your toe in a door or other objects
  • or by participating in activities that put repetitive stress on the toenails, such as running or dancing

These forms of trauma to the toenails often result in a phenomenon called subungual hematoma where blood collects under the nails, which could cause the nail to turn black or purple.

In most cases, a subungual hematoma is not a serious condition and can be treated at home. But if the hematoma is large or if the nail is loose, you should contact or visit the nearest podiatry clinic near you for assessment and treatment.

It is important to avoid trying to remove the blood from under the nail yourself, as this can cause further damage to the nail bed.

If you are concerned about the trauma or if you are experiencing severe pain, you should get checked out sooner rather than later.

Black toenail fungus

Fungal infection is another common cause of black toenails. This type of infection is called onychomycosis which is caused by the fungus class called dermatophytes.

Aside from toenail blackening, onychomycosis can also cause the nail to become thick, brittle, and turn brown, white, or even yellow. It may also cause the nail to separate from the nail bed. The skin around the nail may also become red and swollen.

Onychomycosis is more common in people who have diabetes, peripheral artery disease, or other conditions that impair circulation.

It is also more common in people who have a weakened immune system or a history of athlete’s foot or other fungal infections. Onychomycosis is often spread through direct contact with infected nails or through shared surfaces, such as communal showers.

Other factors that may increase the risk of onychomycosis include:

1. Wearing tight or poorly fitting shoes – tight or poorly fitting shoes can cause the toes to become warm and damp, which can create an ideal environment for fungi to grow.

2. Sweating heavily – excessive sweating can create a warm, damp environment on the feet, which can increase the risk of fungal infections.

3. Having a weakened immune system – people with HIV/AIDS or other conditions that weaken the immune system may be more prone to developing onychomycosis.

4. Having a history of athlete’s foot or other fungal infections – people who have had athlete’s foot or other fungal infections in the past may be more likely to develop onychomycosis.

5. Age – onychomycosis is more common in older adults.


Melanoma can occur on any part of the body including the toenails. This type of skin cancer that occurs under the nails is also known as subungual melanoma.

For starters, it is a rare type of melanoma, accounting for only 1-2% of all melanomas. It affects the nails and can be difficult to diagnose because it can mimic other conditions such as a fungal infection or a bruise.

Subungual melanoma typically appears as a dark or black stripe or spot under the nail or on the nail bed. It may also appear as a change of shape of the nail.

But aside from the discolouration, symptoms of subungual melanoma may also include:

  • Thickening or swelling of the nail
  • Pain or tenderness in the affected area
  • Bleeding or discharge from under the nail

Although it’s a rare condition, risk factors for subungual melanoma include having a history of melanoma, having a family history of melanoma, having a weakened immune system, and having a lot of exposure to ultraviolet (UV) radiation from the sun or tanning beds.

If not treated early, cancer can spread quickly to other parts of the body and can be fatal.

How do you treat black toenails?

Black toenails caused by trauma

Treatment for black toenails caused by trauma will depend on the severity of the injury. Some steps you can take at home to help treat a black toenail include:

  • Keep the nail clean: Wash the affected area with soap and water to help prevent infection. Dry the area thoroughly afterwards.
  • Elevate the foot: If the toe is swollen, try elevating the foot to help reduce swelling.
  • Take pain medication: Over-the-counter pain medication, such as acetaminophen or ibuprofen, can help reduce pain and inflammation.
  • Protect the nail: Wear shoes that have enough room in the toe area to prevent further trauma to the nail. You can also try placing a small piece of padding, such as a bandage, over the nail to protect it.
  • Remove the nail: If the nail is severely damaged or infected, your healthcare provider may recommend removing the nail. This can help prevent further infection and allow the nail to grow back healthy.

If you have a black toenail and are experiencing severe pain, difficulty walking, or other symptoms, it is important to see a doctor for proper diagnosis and treatment.

The medical expert may recommend additional treatments, such as antibiotics or other medications, to help manage the injury.

Black toenails caused by a fungal infection

Toenail fungus can be treated in several ways:

  • Take oral medication: Your healthcare provider may prescribe an antifungal medication, such as terbinafine or itraconazole, to help clear the infection. These medications can be taken orally or applied topically.
  • Use over-the-counter topical medication: There are several over-the-counter antifungal creams, ointments, and sprays that can help treat toenail fungus. These products can be applied directly to the affected nail and surrounding skin.

Make sure to contact a doctor before buying or consuming any of these medications. It’s also important that you’re consistent in taking these and fully commit to the treatment plan designed by your doctor.

During the treatment, you may find that your nail starts to look better, but believe us, the fungus might still be there. The infection isn’t cured until we can’t find the fungus in your toenail clippings. 

Black toenails caused by melanoma

Treatment for subungual melanoma typically involves the removal of the affected nail and the underlying bone. This may be done through surgery or the use of chemotherapy or radiation therapy. The goal of treatment is to completely remove cancer and prevent it from spreading.

In some cases, additional treatments may be needed to address any complications or to prevent cancer from returning. These may include medications, such as immune checkpoint inhibitors or targeted therapies, to help the body fight cancer cells.

It is important to see a dermatologist or a specialist in skin cancer as soon as possible if you suspect that you may have subungual melanoma. Early diagnosis and treatment can improve your chances of a successful outcome.

When to see a podiatrist

Depending on the cause, toenail blackening will resolve on its own over time. And in most cases, black toenails are not a serious concern.

However, if you have a black toenail and are experiencing other symptoms, such as pain, swelling, or difficulty walking, it may be a good idea to see a podiatrist.

Podiatrists like us here at Watsonia Podiatry are medical professionals who specialise in the diagnosis and treatment of conditions that affect the feet, ankles, and lower limbs. We can help you determine the cause of your black toenail and recommend the appropriate treatment.

You can book in to see us here at Watsonia Podiatry by calling us on 03 9432 2689 or booking online here.