Introduction to Black Toenails

Do you want to get into running? If your New Year’s resolutions included taking up running, you may want to consider connecting with the Plano Pacers (if you haven’t already done so). This local running club has over 700 members and hosts monthly races, which makes it an invaluable resource to find support and provide motivation when you are feeling less than enthusiastic about hitting the trails.

Whether you are a novice runner or a seasoned pro, you might take off your shoes and socks following a long run and notice some black toenails, or dark spots on your toenails. This type of toenail issue, though common among runners, can happen to anyone. If your toenails have turned an unfortunate shade of grey, purple, or black, you may be wondering whether to seek medical help.

As well as looking a little unsightly, black toenails can sometimes signal an underlying health issue. So, to help you make sense of your toenail problems, we’ve put together a quick guide to causes and treatments.

What are Black Toenails?

Black toenails are – as the name suggests – toenails that have darkened in color and may feel a little tender to the touch. Some people may only see a small black spot on a single toenail, while others may experience severe discoloration across multiple toes.

What Causes Black Toenails?

While most cases of black toenails are nothing to worry about, some may indicate health conditions that require investigating. The most common causes of black toenails include:

  • Fungal toenails: Although fungal infections usually turn toenails white or yellow, they can sometimes cause black spots due to debris buildup.
  • Melanoma: Melanoma is the most serious form of skin cancer and tends to appear as a dark, misshapen spot. Melanoma lesions can occur anywhere on the body, including under nailbeds.
  • Trauma: Severe or repeated trauma can cause blackened toenails, as well as itchiness, swelling, or pain. Avid runners and dancers are especially prone to experiencing black toenails, as their feet frequently undergo repeated trauma.
  • Other underlying conditions: A wide range of health conditions, including heart disease, kidney disease, anemia, and diabetes can cause dark toenails.

When noted by runners, darkened nails are typically the cause of repeated trauma as a toe hits the front of a shoe during a long run. In such a case, the darkness is either a bruised nailbed or a subungual hematoma (blood that has pooled between the nail and its bed). Besides the darkened coloration, other symptoms in the toe may include tenderness or swelling.

Darkened toenails are more common for runners who wear shoes that are too tight, so a good way to prevent the condition from developing in the first place is to choose footwear that fits correctly. Of course, this is simply good advice that will help you avoid an array of potential issues such as ingrown toenails.

Not all cases of black toenails are experienced by runners, though. Sometimes the darkened coloration is the result of a fungal infection. In other cases, bruising or subungual hematoma happens from a single traumatic incident, like dropping something heavy on your foot.

Foot needing to get black toenails evaluated

When Should You See a Doctor?

As you can see, there are many potential reasons for black toenails, some of which don’t require medical attention. For example, if your toenail blackens after you’ve dropped something heavy on it (ouch!), it’s safe to assume you’re suffering from a bruised nailbed or subungual hematoma (a pool of blood between the nail and nailbed).

However, if your toenails appear to have turned black for no reason or stay black for several weeks, you should visit our office for an assessment.

Can Black Toenails Cause Complications?

In short – yes. Here’s why:

Toenail Fungus Complications

Untreated toenail fungus can permanently damage your nails and spread beyond your feet if you have underlying health conditions such as diabetes or a suppressed immune system.


While rare, melanoma is a severe form of cancer requiring immediate treatment. The sooner such cancers are treated, the better the outcomes for patients. If you see black spots spreading through your nail, make an urgent trip to your doctor. While it’s probably nothing, you must get it checked.

Treating Black Toenails

If your black toenails were caused by trauma, you should protect them with padding and wear loose shoes for a few days. The discoloration should fade after a few weeks.

If you have a fungal nail infection, investing in an anti-fungus cream from the drugstore should help resolve the issue if you don’t have underlying health issues. As we’ve already mentioned, black toenails caused by other problems require medical attention.

Worried About Your Black Toenails? Give Richardson Podiatry a Call!

If you’re concerned about your black toenails and need a professional evaluation, our friendly podiatrists, Dr. Haddad and Dr. Reister, are here to help. They can evaluate your black toenails, figure out the cause, and get you the best treatment available.

Give Richardson Podiatry Center a call at (972) 690-5374 today to schedule an appointment, or fill out our contact form online. Don’t let concern over your black toenails haunt you anymore, get them checked out!