A Black Line on Your Nails Could Be a Sign of Cancer

A black spot or a line could be the result of a blow or other circumstances (infections, consumption of certain medications, etc.) and it doesn't necessarily means you have cancer.
A Black Line on Your Nails Could Be a Sign of Cancer

Last update: 22 January, 2021

How often do you go to a nail salon for a manicure? Jean Skinner works as an aesthetician in Uckfield, East Sussex (United Kingdom), and shared her story about a black line a few days ago. It scared more than one person.

It all started when one of her clients asked her to apply a dark color on their nails to cover the black line that went across them. Nevertheless, Skinner advised her to consult a doctor because cancer symptoms present themselves this way in some cases.

The diagnosis confirmed the person had ungual melanoma, a type of cancer. These dark or bluish spots don’t just appear on nails: there’s also a change in their size, color, and shape.

Note that dark spots aren’t always linked to cancer. These are some situations in which their presence is completely normal:

  • Use of medications: The side effects of some drugs include nail pigmentation, after several days of use.
  • During pregnancy: It’s possible for nails to acquire a brownish stain during pregnancy. However, there are no serious consequences.
  • Infections: The appearance of nail fungus changes nail color.
  • Hematomas: If the spot is a mixture of brown and red dots, then the dark spot is most likely due to a blow.

Jean Skinner’s story indicates the importance of paying attention to certain signs of the body.

When to worry about a black line

Even though it’s uncommon, ungual melanoma can appear in children. The width of the black line is larger than a sixteenth of an inch, and it’s not just one color, there are different tones of brown within the same line.

It changes as time goes by, and generally, the skin around the nail is also dark in color.  In most cases, ungual melanoma doesn’t just affect one nail. However, there are other symptoms that can present themselves in various areas of the body such as the toes and scalp.

Is a black line really dangerous?

Melanoma is the most aggressive kind of skin tumor because it spreads rather quickly into other organs, even to distant ones such as the small intestine, the eyes, the brain, and even to the heart.

A doctor holding a patient's hand.


There are different ways to treat melanoma in your skin. Everything depends on the state of the tumor and the patient’s physical conditions. These are some of the treatments:

  • Radiotherapy: This method keeps the cancerous cells from growing. It’s a localized treatment. In other words, it only affects the area where the melanoma is found.
  • Surgery: This method is the most used one. For this treatment, the tumor and the tissue found around it are removed. The goal is to keep cancer from reproducing to areas around it.
  • Chemotherapy: This is used when melanoma has spread to other parts of your body. The patient is given a combination of drugs. This includes a localized application.
  • Immunotherapy: the goal of this treatment is to increase your immune system’s strength.


As in other cases, a nail melanoma prognosis depends on how soon you get a diagnosis and begin treatment. Unfortunately, the expectations are worse than those of cutaneous melanoma because the diagnosis is late in many cases.

It’s essential for the primary care physician to be familiar with the characteristics of this type of melanoma, as this increases the chances of successful treatment.


One of the largest causes of melanoma is careless sun exposure. You must keep the following in mind when it comes to your skin:

  • Avoid sun exposure during peak hours (between noon and 4 pm).
  • Get in the habit of using a sunscreen every day (apply it half an hour before going out, especially if you’re going to a pool or a beach.)
  • Drink at least 2 pints of water as the sun dehydrates your body and you must regulate your body temperature.
  • Protect your skin from tanning. Exposure to UV rays speeds up the skin aging process and increases the risk of skin cancer.
  • Pay attention to any irregularity. Don’t overlook the signals! Keep an eye on your nails and moles for any changes in color or size.
A woman putting on sunblock so she doesn't get a black line on her nail.

Listen to your body

It’s very common to confuse melanoma with benign diseases such as nail fungus or common bruises. It’s for this reason that patients don’t seek help until the advanced stages of the condition.

So, don’t self-diagnose, for your own wellbeing and consult a dermatologist if you find any skin abnormalities. This is the only way to obtain a good diagnosis and proper treatment.

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  • Jefferson, Julie, and Phoebe Rich. “Melanonychia.” Dermatology research and practice vol. 2012 (2012): 952186. doi:10.1155/2012/952186
  • Singal, Archana, and Rahul Arora. “Nail as a window of systemic diseases.” Indian dermatology online journal vol. 6,2 (2015): 67-74. doi:10.4103/2229-5178.153002