Dealing with a discolored toenail

Last Modified: 4/05/2022


This post was written by Ashley Bojrab, DPM, FACFAS, ABPM, PPG – Podiatry.

My friends ask me questions about their feet all the time. It comes with the territory! One that I’ve gotten more than once is, “Why did my toenail turn black?” They may have removed toenail polish and noticed a black toenail or taken off their work boots and noticed a nail was purple. This can be a startling discovery, but there’s typically an easy explanation for why the discoloration is occurring.


Toenails can be damaged fairly easily, and when this happens bleeding can occur underneath the nail, causing a black or purplish discoloration. Often toenails turn black because of some type of trauma. Whether it be stubbing your toe on the bed or nightstand, improperly fitted shoes, running or a pet stepping on your foot. These can all cause a break in the skin under the nail. When this happens, bleeding can occur, and that can cause partial or total involvement of the toenail.

If the toe was only partially involved in the trauma, it’s not uncommon for the toenail to have a black spot initially that, over the course of six to nine months, grows out toward the tip of the toe. If the whole nail is involved, the toenail may fall off or need to be surgically removed.  Depending on how bad the trauma is, it can break the bone underneath the nail and must be treated accordingly.  


If the black discoloration begins to spread over time and does not grow out, this could be concerning for melanoma, a type of skin cancer. If this is the case, it is very important to have the area evaluated by your medical team.

Nail fungus

Another reason why toenails turn black is nail fungus. This can darken the toenail and cause thickening of the nail with white crumbly debris under the nail. Nail fungus can be unsightly and very difficult to treat, which mean permanent damage to the nail. Over-the-counter treatments can be ineffective, so seek professional medical treatment if you are experiencing these symptoms.


You can prevent black toenails from developing by wearing socks and properly fitted shoes. Feet can change over time, so have your feet measured regularly by a professional. Keep shoe gear clean by spraying with disinfectant, as needed, and making sure shoes are always dry.  Remove toenail polish frequently so that the toenails can breathe and you can inspect the nail for any discoloration. Wear shoes around the house to prevent any injuries to the toes.

As always, if you have any concerns about your toes, please contact your podiatrist for further evaluation.

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