Why Do Toenails Get Black?

If you have a black toe or black toenail then it is understandable that you might be alarmed and want to get to the bottom of what is causing the discolouration. However there is not just one cause of a black toenail but several which can make it quite difficult to identify the problem and to treat/avoid it. Here we will look at a few causes of a black toenail and how to avoid them or treat them.

Black toes from walking

Black toenails, or toenails with a black mark on them, are a common problem that occurs for those who do a lot of walking or running. This occurs when the bed of the toenail is injured and this happens whenever the shoe allows the foot to slide forwards in the shoe, which means that the toenails hit into the end of it and then are forced back farther into the toes themselves. When the nail grows further it will then have a black mark on it where the trauma occurred. While this is not something that will likely cause any serious damage, it is important to avoid it from happening to avoid damage to your toenail and because it can look unattractive, particularly for women who maybe want to show their toes in open-toed sandals or heels. Here we will look at a few ways to prevent it from happening.

Avoiding a black toe from walking

To prevent this from happening you should get shoes that fit you well. When buying your shoes try to ensure that that your feet reach the ends and that there isn’t too much space for your foot to move forwards. Press on the end of the shoe and you should be able to feel your toes. At the same time though you should avoid them being too tight as this can mean that your toenails are constantly under pressure and constantly being pushed into the beds. You should ensure that you tie the laces and the Velcro up tight in order to avoid the foot moving around too much as well, and to wear thick socks that can pad the ends of your feet and prevent them from sliding.

Black toenails from bruising

In some other cases your black toenail may be a result of bruising beneath the nail. This is highly painful and generally caused by some kind of trauma – stumping the toe or perhaps dropping something on it. If the appearance is alarming then you should make sure that you see a doctor who may drain the blood out from underneath. This is only usually necessary if the bruise or blister is enough to lift the toenail up away from the toe and if it is causing a large amount of discomfort. Draining will normally be done with a red hot needle that will also sterilise the area. It is also important to see the doctor in case the toe is broken in which case it will normally be taped to your other toes or a splint to ensure that it heels as straight as possible.

Other causes

If you are not sure of the cause of your black toenail then you should always see a doctor. A black toenail is often a harmless sign of bruising or damage to the nail bed, but in some other cases it can be a result of melanoma which is a type of skin cancer. If this looks more like a streak of blackness rather than a ‘blotch’ or discolouration of the entire nail, then this is another sign that it may be cancer – particularly if it does not disappear on its own after a brief period of time.

Whenever you get a black nail whether from walking related injuries to the nail bed or from a bruise beneath it you may be likely to lose all or some of the nail. After about a month the toenail will be shed but it may begin to detach sooner than this and be ‘loose’ for a while. You will then grow a new toenail in its place which will partially have caused the dead toenail to fall off. It can take several months before your toenail looks entirely ‘normal’.

Be careful during this period to protect our toe as it can be very painful having no nail. The purpose of the toenail is to protect the toe and this is because we have a lot of nerve endings in the tips of our fingers and toes. Ensure that you keep your toe protected then while your toenail grows back but allow it to air to ensure that the toenail forms healthily. You can also ensure a high calcium diet during this time to provide the body with the raw materials it needs to create a nail. Where steel tipped boots if you have them so that your toes are protected and avoid tight or woolly socks which can rub on the toe and cause discomfort while starving your toe of oxygen. Take it easy for a while and cease any activities that cause your toe to hurt such as walking or running.


  1. I have black toenails on both of my feet and I was wondering what actually causes all of them to turn black like that?

  2. Very helpful information.

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