Medically reviewed by Danielle McNeil, D.P.M
Toenail fungus, also called onychomycosis or tinea unguium, is a fungal infection that can change the appearance of your toenails. They’re quite common, affecting up to 14% of people.
While fungal nail infections aren’t a serious health problem, they can sometimes cause pain. More often, though, they’re a cosmetic problem, as the toenail may become thick, discolored, or cracked.
This article will help you see what kind of toenail fungus you might have, who’s especially susceptible to toenail fungus, and whether you may be dealing with a different type of condition.
What Do Different Types of Toenail Fungus Look Like?
You can pick up a toenail fungus from your environment. They often get in through small cracks in the nail or the skin around it.
The fungus may infect one nail or multiple nails and the surrounding skin. Each type has its own signs, symptoms, causes, and appearance.
The most common type of toenail fungus is called subungual onychomycosis. It may affect the tip or sides of the nail. Look for:
Lifting of the nail
The fungus, often Trichophyton rubrum, typically invades the nail bed and the underside of the nail plate. It then moves toward the base of the nail.
Less often, the infection begins at the base of the nail. This area then thickens and becomes discolored. This is associated with a compromised immune system, especially human immunodeficiency virus (HIV).
What Does "Subungual" Mean?
"Sub" means "under," and "ungual" refers to a fingernail or toenail. Thus, "subungual" means "under the nail."
White Superficial Onychomycosis
White superficial onychomycosis is caused by a variety of fungi that invade the top layers of the toenail. It creates symptoms on the surface of the nail that include:
White, well-defined flaky patches
Eventually, patches that become rough, soft, and crumbly
The most common cause of white superficial onychomycosis is the fungus Trichophyton mentagrophytes.
Related: What Causes Nail Pitting?
Candida (yeast) onychomycosis is most common in people who:
Have chronic problems with yeast infections, possibly due to an impaired immune system
Have previously injured or infected nails
Regularly have wet feet
Work with chemicals such as detergents and soaps
Rough nails with pronounced ridges
Breakdown of the nail surface
Infection of the soft tissue around the nail
Infection that begins suddenly and may worsen quickly
Less often, opalescent, pitted nails
This type of infection is especially common in agricultural workers due to exposure to wet environments, mud, and animal waste.
Who’s Susceptible to Toenail Fungus?
Anyone can get a fungal toenail infection. But you may be more likely to develop it if you have:
A deformity in your nail or foot
Recent foot trauma
A compromised immune system from cancer, other diseases, or medication
Poor circulation in your legs
Other fungal infections
They also grow more likely with age.
Bacterial Plus Fungal Infection
If a bacterial infection occurs along with your fungal infection, it can cause serious illness. Diabetes or a compromised immune system may increase this risk.
Toenail Fungus Treatment by Type
Toenail fungus can be difficult to clear up, and it usually doesn’t go away without treatment. You’re more likely to be successful if you start toenail fungus treatments right away.
You’ll know the treatment is working when you see healthy growth at the base of the nail.
If you have a very mild fungus, you may be able to keep it from getting worse by:
Cleaning your toenails regularly
Filing off white marks
Using an over-the-counter antifungal liquid
Keep in mind that this is a temporary measure and not a solution. Even if it seems to go away, the fungus is likely to come back. It’s best to make an appointment with a healthcare provider for a proper diagnosis and treatment.
Antifungal nail creams are widely available in drug stores and online. You may want to ask your healthcare provider or pharmacist to recommend a product, as not all of them are proven effective. You might also want to use a nail-softening cream, which can make the infected areas easier to scrape off.
It may help to disinfect your socks and the insides of your shoes to ensure they’re not reintroducing the fungus when you wear them.
Learn More: Topical Treatments for Toenail Fungus
Prescription-strength topical antifungal medications are a common treatment option for toenail fungal infections. Topical medications that are approved by the Food and Drug Administration (FDA) include:
Side effects of topical agents can include:
Stinging or burning
Prescription oral (by mouth) antifungal medications may be used for a laboratory-confirmed toenail fungus. The most common treatment is a 12-week course of a drug called terbinafine.
However, some research suggests fungal infections can become resistant to terbinafine, so let your healthcare provider know if treatment doesn’t seem to be working.
For Candida infections, common drugs include:
Side effects of oral antifungal medications can include:
Loss of taste
Nausea and diarrhea
It’s also common to combine oral and topical treatments.
More and more, experts are urging healthcare providers to get a laboratory diagnosis before they start treatment in a patient. That way, they can start you on the proper treatment as soon as possible.
It may take several months or even a year for your fungal infection to clear up.
In the case of a severe and painfully malformed nail, your healthcare provider may suggest removing the entire nail permanently. This is a minor procedure that’s usually done with a local anesthetic to numb the area.
Learn More: What Are the Best Toenail Fungus Treatments?
Fungal Infections Can Spread
An ongoing fungal infection can spread from your toenail to other places, or to your nails from somewhere else. If you have or suspect a toenail fungus, take swift action to keep the problem from becoming worse.
Other Conditions That Look Like Toenail Fungus
Not all conditions that affect your toenail are fungal infections. Other conditions that can resemble a toenail fungus are:
Psoriasis: Psoriasis is an autoimmune condition affecting the skin and nails. It causes white, yellow, or brown discoloration, pitting, crumbling, blood under the nail, and the nail separating from the toe.
Skin cancer: When melanoma skin cancer forms under and around the nails, it can cause dark streaks or bands, dark skin around the nail, lifting or splitting, and bumps under the nails.
Darier's disease: This rare skin condition may cause red and white streaks in the nails and irregular texture. Symptoms may also include small pits on the soles of the feet and wartlike blemishes on the skin.
Yellow nail syndrome: This extremely rare condition is characterized by malformed toenails and fingernails, along with breathing problems and puffiness.
Alopecia areata: This autoimmune disease causes hair loss and, in some cases, ridges or pits in the nails.
Other types of foot fungus: Other fungal infections, such as athlete’s foot, can spread to your toenails, making them thick, brittle, and brownish-yellow. They are caused by the same types of organisms and can spread to the nail easily.
Seeing a healthcare provider is the best way to determine what’s causing your toenail symptoms and find the right treatments.
Related: Causes of Yellow Nails
Is Toenail Fungus Contagious?
Yes, toenail fungus is contagious. Just as it can spread to other nails or skin, it can also spread to other people.
You may catch or spread toenail fungus in the shower—including at the gym—or through practices such as sharing toenail clippers or shoes. This means that preventive measures are especially important when you have a fungal infection.
How to Prevent Toenail Fungus
You can take steps to prevent toenail fungus, such as:
Keeping your feet dry and clean
Washing regularly with soap and water
Trimming your toenails regularly
Disinfecting nail clippers between uses
Wearing sandals or flip-flops in public showers or locker rooms
Not sharing nail clippers
Changing socks and shoes more than once a day
Wearing shoes made of materials that breathe
Wearing socks composed of natural fibers
Not polishing infected toenails
Treating athlete’s foot
If you get pedicures, be sure to choose a clean, licensed salon. Ensure they sterilize all instruments before using them on you. You may also be able to bring your own supplies, but if they’ve been used, disinfect them first.
Toenail vs. Fingernail Fungal Infections
Both toenails and fingernails can develop fungal infections. However, it’s more common in toenails.
When to See a Healthcare Provider
You should see a healthcare provider such as a podiatrist for a toenail fungus if you notice your toenails are:
You may need more aggressive treatment if:
The infection is severe.
The infection spreads to other nails or body parts.
Home remedies aren’t working.
You have a condition that could make an infection especially hard to treat.
Toenail fungal infections are common and can be difficult to treat. You may be prone to them if you have diabetes or a weakened immune system. Symptoms may include thickening, discoloration (white or yellow), crumbling, lifting, and spreading to the skin around the nail.
Treatment may involve some combination of over-the-counter products, prescription-strength topical treatments, and oral antifungal medications. You can prevent the spread of fungal toenail infections by keeping your feet clean and dry, wearing flip-flops in public showers, and sterilizing pedicure instruments after using them.
Many conditions cause similar symptoms. See your healthcare provider if you notice concerning changes in your toenails.
Read the original article on Verywell Health.