Why are my toenails going black?

Discoloured toe nails are one of the most common presenting complaints we have in our Podiatry clinics across Far North QLD. As a general rule, the discolouration is secondary to bruising from previous trauma to the nail. The trauma results in bleeding under the nail and as the blood has nowhere to escape, it becomes trapped, dries out and can remain there for sometime. The severity of trauma can vary from a simple stub of the toe against the bed leg (we can all relate to this!) or to the extent of a crush injury.

So what if your toenail has become black and you can’t remember any incidents? Chances are, this is related to your footwear. Shoes that are too big big or small can also cause repeated trauma to your nails. If your shoes are too big, the extra room in the shoe allows your foot to slide in the shoe and hit the end. If your shoes are too small, your foot doesn’t have room to slide and repeatedly hits the end of the shoe. This is a common issue that we see in runners across our clinics, particularly those running long distances. 

Here are some important FAQ’s regarding black toenails:

  • If my toenail is black, does it mean it is dead?

As a general rule, one traumatic incident to the nail, isn’t enough to ‘kill it’. This only occurs after repeated trauma to the nail and the root. The damaged nail will likely fall off and a new one will grow underneath to replace it. 

  • If I am certain there has been no trauma to the nail, what else could it be?

If this is the case, we strongly recommend a consultation at one of our Podiatry clinics in Cairns. Although uncommon, skin cancers can develop under the nail so further assessment may be required. Particularly given the climate that we live in and the higher incidence of skin cancers. 

  • How do I tell if the black nail is fungal?

As a general rule, a fungal infection under the nail results in a white/yellow discolouration rather than a dark one. The nail will also often have a brittle appearance. If you would like to be sure, consult one of our Podiatry clinics in Cairns and one of our friendly Podiatrists will conduct a thorough assessment of the nail.

  • Will I lose my toenail if it is black?

This really depends on the severity of the damage and the amount of bleeding under the nail. If mild, the pressure from the dry blood generally isn’t enough to cause the nail to lift. However, if the trauma is significant, the amount of bleeding results in the nail lifting from the bed (if it hasn’t already from the trauma) and will slowly fall off.

  • What can I do to reduce the risk of my nail falling off after trauma?

The best way to reduce the risk of nail damage and pain, is to consult a Podiatrist within the first 48hrs of the injury. The treating Podiatrist will be able to drain some of the blood out from underneath the nail, hence reducing pressure and improving comfort significantly. Ice application can also be beneficial as it can close the capillaries and hence reduce the severity of the bleeding. 


If you have a black toenail that is causing pain or you are concerned about, be sure to see us at one of our Cairns Podiatry clinics for an assessment. Appointments are readily available online at www.fnqpodiatry.com.au or call on 40 455 749