Toenail Fungus: Causes & Symptoms

by Meenakshi Nagdeve last updated -

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Toenail fungus may be among the worst in the unsightly infections, causing your toenail to change color or crumble. Therefore, it is important to know what are the causes, and how to identify it.

What is Toenail Fungus?

Toenail fungus is a broad categorization of any fungus that embeds itself beneath the toenail. Technically known as onychomycosis, toenail fungus tends to be caused by two different dermatophytes – fungi that require keratin for growth. Keratin is conveniently found in your toenails, which makes them an ideal location for infection.

In the case of toenail fungus, the condition will likely start with a small white or yellow dot beneath your toenail. If not addressed, and provided with good conditions for growth, that small dot will grow and begin to weaken the nail, followed by dullness, scaling, and pits on your nails.

While toenail fungus is not inherently dangerous, it can be an unsightly and uncomfortable condition, while also opening up your body to other infections, if the toenail becomes cracked and broken into an open wound. Fortunately, since this condition is so common, a considerable amount of research on signs, symptoms, causes, risk factors and treatments has been conducted.

Close up of an image of podologist checking the left foot suffering from toenail fungus infection


The most common symptoms of toenail fungus include discoloration of the nail in yellow and white streaks, as well as physical damage to the nail, such as crumbling at the edges of the nail, or pits forming in the surface of the toenail. Yellow spots may also appear at the base of the nail, near the nail bed, and in the most severe cases, the toenail will fall off completely. Your nail will also likely lose its shine and take on a dullness, and may also become distorted or bent out of shape, as though it is growing at the wrong angle.

If you see scaling under the nail, or visible cracks/pits in the nail, there is also a good chance that other debris will get beneath the nail, resulting in a brown color, a dirtiness that is difficult to clean off. There will typically be an odor to the toenail when it is infected, as is true with other types of infections on the skin. The toenail will likely become thicker and more brittle as the infection spreads.

These symptoms are not unique to toenail fungus, however, so to get an accurate diagnosis, it is necessary to visit your doctor for a formal examination. At that point, you can discuss treatment options specific to your condition.


Toenail fungus is caused at the root by dermatophytes, which are fungi that require keratin to survive and thrive. However, there are a number of other causes and risk factors for toenail fungus, such as excessive dampness or perspiration, physical exertion, wearing closed-toed shoes, diabetes, old age, injuries to the nail, poor circulation, weak immune system and exposure to public water.

  • Damp Environment: Fungal infections thrive in areas that are damp or perpetually moist, which is why showers and locker rooms are the perfect places to catch one of these nasty infections. Avoid using other people’s towels and wear shower shoes in public locker rooms whenever possible.
  • Physical Exertion: If you are an athlete, your physical activity likely causes an excessive amount of perspiration in your shoes and socks. If you wear old socks or shoes or leave them on for too long following a workout, the conditions are ripe for a toenail fungus infection.
  • Shoe Choice: Always wearing closed-toed shoes can promote a constant environment where this fungus can thrive. Let your toes breathe a bit and ensure that you regularly wash between your toes and under the edge of your toenails when you shower.
  • Age: As we age, our nails naturally become more brittle and susceptible to infection, combined with a decrease in personal hygiene and a preference for warmer temperatures. Furthermore, the immune system becomes weaker as we age, making the natural response to infections less powerful.
  • Diabetes: One of the major symptoms if diabetes is a decrease in circulation, particularly in the extremities, like the toes. Where there is a lack of resources to repair or heal infections, such as in the toes, infections can take hold much more easily.
  • Circulation: There are other reasons why your circulatory system may struggle to deliver the necessary nutrients to your toes and nail beds. If you are overweight, have high blood pressure, wear constricting socks or take certain medications, your circulation may be low, leaving you vulnerable to toenail fungus.
  • Public Pools: Swimming in public pools opens your toes to a veritable cesspool of potential fungi, so if you have an infection or are prone to developing them, avoid these types of public spaces.
  • Immune System Issues: weakened immune system can happen due to illness, autoimmune disease, nutrient deficiency and many other factors, leaving your entire system more vulnerable to infection.
  • Injuries: If your toenail has been damaged by an injury or if your nail bed is exposed for any other reason, your risk for developing toenail fungus increases considerably. Protection Status
About the Author

Meenakshi Nagdeve, Co-Founder, Organic Facts is a health and wellness enthusiast and is responsible for managing it. She has completed the Nutrition And Healthy Living Cornell Certificate Program, Cornell University, US. She holds a Post Graduate Diploma in Management from IIM Bangalore and B. Tech in Metallurgical Engineering and Materials Science from IIT Bombay. Prior to this, she worked for a few years in IT and Financial services. An ardent follower of naturopathy, she believes in healing with foods. In her free time, she loves to travel and taste different types of teas.

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