Toenail Fungus: Symptoms, Causes, and Treatment Options

By Nena Luster DNP, MBA, FNP-BC
Medically reviewed checkmarkMedically reviewed
June 7, 2022

Changes in the appearance of your toenails can be distressing, especially if you’re unsure of what’s causing your toenails to appear dry, brittle, cracked, or discolored.

Toenail fungus is a common nail infection that can cause your toenails to look and feel different.

Understanding the most common signs of a toenail fungal infection can help you know when to seek help to start treating the infection. 

In this article, I’ll cover the symptoms of toenail fungal infection, its risk factors, and causes.

I’ll also cover how a toenail fungal infection is diagnosed and which treatment options are available and effective.

Finally, I’ll explain when you may want to speak with your medical provider to confirm a toenail fungal infection. 

What is Toenail Fungus?

Toenail fungus is a common fungal nail infection (also called onychomycosis) that can cause nails to become brittle or change color.

It’s estimated that somewhere between 3-12% of the general population is affected with nail fungus.

A fungal nail infection can occur on the toenails or fingernails, but most fungal nail infections affect the toenails.

The toenails on the big toes are most often affected by toenail fungus.

Concerned about toenail fungus? Chat with a medical provider using K Health.

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Symptoms of Toenail Fungus

The main symptoms of toenail fungal infection are a change in the appearance and in feel of the toenails.

Specifically, symptoms can include:  

  • Change in nail shape
  • Whitish-yellowish or brownish discoloration of the toenails
  • Brittle or crumbly toenails
  • Toenails that hurt or become painful
  • Loosening or lifting of the toenail
  • Dull toenails that have lost their usual luster and/or shine 
  • Toenails that appear fragile or cracked 
  • White or yellow patches that form on the surface of the toenail (sometimes these patches appear as small dots, other times they appear like spread out streaks)
  • Discolored or brittle parts of the toenail that detach from the nail bed

Risk Factors

Fungal toenail infections can affect anyone.

But there are some people who may be more likely to be affected, including older adults and people who have: 

  • Diabetes
  • Athlete’s foot
  • Minor skin or nail injuries
  • Deformed nail or nail disease
  • Frequent contact with infectious fungi (in places like swimming pools, steam rooms, and saunas)
  • A weakened immune system (including those living with a chronic condition like HIV or those who take medication that suppresses the immune system)
  • Blood circulation issues (often a result of diabetes or peripheral artery disease (PAD))
  • Damaged nails
  • Tight shoes that don’t allow air to reach your feet
  • Certain skin conditions, including psoriasis

Additionally, moist working conditions can put some people at a higher risk of fungal nail infections in general.

For example, professional cleaners and dishwashers are more likely to get fungal nail infections on their fingernails.


A toenail fungal infection can be caused by many different types of fungi.

These fungi can live on dead tissues of the hair, nails, and outer skin layers as well as in your surrounding environment.

The fungi that are responsible for most toenail infections are called dermatophytes.

A small crack in your nail or the surrounding skin can allow fungi to enter the nail and lead to an infection. 

Other types of fungal infections can also cause a toenail infection, including:

  • Athlete’s foot: Athlete’s foot is a fungal infection that affects the skin and tissue of the feet. It’s also referred to as tinea pedis or ringworm of the foot. Certain people can be at a higher risk of developing athlete’s foot, including people who wear closed shoes, keep their feet wet for long periods of time, and sweat excessively. Athlete’s foot is easily spread through direct contact with people who have the infection and/or direct contact with items like shoes, socks, and shower and pool surfaces. Symptoms of athlete’s foot include red and itchy feet, burning and stinging pain on the skin, and areas of skin that ooze or get crusty.
  • Jock itch: Jock itch is a fungal infection that affects the groin area. It’s also referred to as ringworm of the groin. People who are at higher risk of getting jock itch are adult men, teenage boys, and people who have another type of ringworm infection (including athlete’s foot). Similar to athlete’s foot, jock itch can be spread by direct skin-to-skin contact or by direct contact with items that touch the affected area, including unwashed underwear or clothing. Symptoms of jock itch include red, raised, and scaly patches that form on the skin and can blister and ooze. In some cases, jock itch can also abnormally darken or lighten skin, sometimes permanently.


Confirming diagnosis of toenail fungus is fairly straightforward; your provider can usually confirm whether or not you have a toenail infection with a physical examination of your toenails.

If there is any question about the diagnosis, your medical provider may collect scrapings from the nail and examine them under a microscope.

Inspecting nail scrapings under a microscope will also enable your provider to identify the type of fungus causing the infection. 

Sometimes, a fungal infection can be difficult to distinguish from other nail conditions, like psoriasis. In these cases, your provider may send a sample of your toenail to a laboratory for a fungal culture.

The results of this process can take anywhere from 2-6 weeks.  

Other tests may also be recommended, including an examination of your nail tissue performed by a laboratory, but these are less common.


Toenail fungal infections can be tricky to treat. But there are several treatment options available, including:

  • Nail polish: A prescription colorless nail polish can topically treat nail fungus when it contains the ingredients amorolfine or ciclopirox. Amorolfine and ciclopirox can help to stop the fungus from growing and, in some cases, kill the fungus causing the infection.
  • Treatment sets: Treatment sets that contain a urea-based cream may work to soften the toenail, after which you can scrape the affected toenail off with a spatula. The skin underneath is then treated with a topical cream containing bifonazole. 
  • Antifungal tablets: Oral antifungal medications may be needed to treat certain cases of toenail infections. However, these medications usually need to be taken for many months and can cause certain side effects, including liver issues. 
  • Nail removal: In severe cases, your provider may recommend removing the affected nail completely.

Unfortunately, most OTC topical treatments found at drugstores are not effective at treating a toenail fungal infection

The best treatment option for you may depend on the type of fungal infection you have, which is why it’s important to speak with a medical provider if you notice signs of a toenail fungal infection.


Fungi love dark, moist, and damp environments, so keeping your feet and nails dry can help to prevent a toenail fungal infection.

Other preventive methods that can help include:

  • Wearing shoes that fit well and allow your feet to breathe 
  • Not wearing the same shoes multiple days in a row
  • Removing shoes as often as possible throughout the day
  • Keep your toenails short and clean
  • Wearing protective shoes (like flip-flops) when using public swimming pools, showers, changing rooms, etc.
  • Ensure that any nail salons you visit properly sanitize instruments after each use (or bring your own instruments for the specialist to use)
  • Don’t share towels, shoes, socks, or nail clippers
  • Washing socks, bedding, and towels at 60 degrees Celsius (or using special laundry sanitizers that can effectively kill fungal spores when washing clothing at low temperatures)

Concerned about toenail fungus? Chat with a medical provider using K Health.

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When To See a Medical Provider

You can reach out to your medical provider if you’re experiencing any symptoms of a toenail fungal infection, including:

  • Discolored nails that appear yellow, brown, or white
  • Toenails that are brittle or thick
  • Toenails that are fragile or cracked

Symptoms that warrant more immediate medical attention are:

  • Fungal infection that doesn’t go away or improve 
  • Toenails that are painful to touch, red, or drain pus

How K Health Can Help

Did you know you can get affordable primary care with the K Health app?

Download K Health to check your symptoms, explore conditions and treatments, and, if needed, text with a clinician in minutes. K Health’s AI-powered app is based on 20 years of clinical data.

Frequently Asked Questions

What is the best way to get rid of fungus on your toenails?
There are several treatment options for a fungal toenail infection, some of which may depend on the type of fungus and the severity of the infection. Antifungal medications taken orally may be the most effective option, but they require a provider’s prescription and are not a good option for everyone due to the potential side effects.
Can fungus on toenails be cured?
Fungal toenail infections can be tough to treat, but it’s possible to cure most toenail infections. If you’re experiencing brittle, cracked, or discolored toenails (or any additional symptoms of a fungal toenail infection), it’s important to reach out to your provider for their treatment recommendations. The sooner you start treatment, the easier it is to treat.
What happens if you leave toenail fungus untreated?
Toenail fungus is not likely to have serious consequences in otherwise healthy people, but it will not resolve on its own. If left untreated, toenail fungus can remain on the toenail or spread, thickening the nail and making it difficult to walk or move around easily. Untreated toenail fungus can also increase the risk of a bacterial infection of the surrounding skin in people with certain medical conditions, like diabetes, HIV, or other chronic, immunosuppressive conditions.
K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

Nena Luster DNP, MBA, FNP-BC

Nena Luster is a board certified Family Nurse Practitioner with over 14 years of experience including emergency medicine, urgent care, and family practice.