What Is Nail Fungus?

Medically reviewed by William Truswell, MD

Nail fungus (medically known as onychomycosis) is a common fungal infection that occurs when fungi in the environment enter your nail bed (the tissue below your nails). Generally, nail fungus affects the toenails, but it's possible to experience symptoms in the fingernails, too. Common symptoms include discoloration, fragile or brittle nails, and cracking.

Certain factors like older age, having a weakened immune system, and living with health conditions such as diabetes can increase your risk of this condition. About 10% of the general population develops nail fungus, but over 50% of people over the age of 70 have this condition. But treatments like oral medications, topical creams, and nail removal can help improve symptoms.

Symptoms

Nail fungus affects your toenails and fingernails, which may cause symptoms such as:

• Nail discoloration, making the nails look white, yellow, or brown

• Cloudy or chalky white-colored patches in the nail

• Changes in the nail shape

• Thickening of the nail

• Brittle, thinning, or fragile nails

• A gap between the nail and the nail bed

• Buildup of debris under the nail

• Cracking or splitting in the nails

Keep in mind: symptoms can develop in one or more nails. Generally, the longer you wait to treat nail fungus, the worse symptoms can become. While pain is rare with nail fungus, severe cases of this condition may cause discomfort when wearing shoes or gloves.

Related: What Causes a Toenail to Turn Black?

What Causes Nail Fungus?

Nail fungus occurs when certain fungi called dermatophytes infect the tissue under the nail or nail bed. These dermatophytes can enter your nail through cuts in the surrounding skin, cracks in the nail, or spaces that develop between the nail and nail bed. Once they infect the area, the fungi reproduce which causes symptoms to occur.

It's easy for nail fungus to spread through direct contact with infected surfaces or skin. It's common to catch fungi if you walk barefoot in places like hotel carpets, on gym or locker room floors, or around pools. Sharing towels or nail clippers can also spread the infection. It's also common to develop nail fungus if you wear moist and sweaty socks or shoes.

Risk Factors

While anyone can develop nail fungus, some people have a higher chance of experiencing symptoms. Factors that can increase your risk include:

• Being over the age of 60

• Residing in a hot or humid climate

• Having sweaty feet or poor blood circulation

• Walking around on damp surfaces

• Receiving cancer treatment or living with cancer

• Living with health conditions like diabetes, psoriasis, or HIV/AIDS

• Previously experiencing a nail infection or injury

• Recently undergoing an organ transplant

Diagnosis

If you have symptoms of nail fungus, it's a good idea to reach out to your healthcare provider for proper testing. During the diagnostic process, your provider will rule out conditions that may cause similar symptoms. These conditions include:

• Toe injury

• Psoriasis

• Skin cancer

• Contact dermatitis

• Yellow nail syndrome

In some cases, your healthcare provider will be able to diagnose a fungal infection through a visual physical exam. But to confirm a suspected case, they’ll collect a sample of a toenail clipping and evaluate it under a microscope. Once they send the toenail sample into the lab, they can learn the specific fungi that are causing your symptoms and prescribe appropriate treatment. Your healthcare provider may work with a dermatologist (skin doctor) or podiatrist (foot doctor) to guide treatment.

Nail Fungus Treatment

Though it doesn’t usually lead to complications, nail fungus can sometimes be difficult to treat. As your dermatologist or podiatrist will tell you, it typically takes a year or more before you see results. That said, oral medications, topical creams, nail removal, and laser therapy are some options for effectively treating a fungal infection.

Oral Medications

Healthcare providers prescribe two classes of antifungal medications: azole and allylamine, that you can take by mouth. Your provider will prescribe these drugs for three weeks to a year, depending on the severity of your symptoms. Common medications include Diflucan (fluconazole), Sporanox (itraconazole), and Lamisil (terbinafine). These are up to 70% to 76% effective in getting rid of nail fungus.

Topical Treatments

Medicated nail lacquer that you apply twice a day directly on affected nails is another treatment option. Ciclopirox 8% is the only such prescription solution available U.S. Because the keratin (a type of protein) that makes up nails is hard to penetrate through, this treatment is only effective about 9% of the time.

There are also several over-the-counter medications, including Nail Renew (a solution of cyanoacrylate, undecylenic acid, and hydroquinone) and a topical cream called Lamisil (terbinafine). Current research shows that the effectiveness of these treatments is limited.

Nail Trimming or Removal

Some studies have shown that regularly trimming the affected nails or removing them can help improve symptoms. Experts recommend nail removal alongside other treatments, such as oral or topical medications. For instance, researchers found this work to make Ciclopirox 8% (the nail lacquer) more effective, raising the cure rate to about 77%.

Laser Therapy

Laser treatments, in which laser lights are directed to affected ideas, are FDA-approved to treat nail fungus. Though laser therapy is effective, research shows that medications are more successful in getting rid of nail fungus.

Complementary Methods

Some people with nail fungus also try applying herbal ointments to the affected nails. According to a review of the literature, there’s some evidence that snake root extract and menthol (Vick’s Vaporub) are effective. There’s early evidence that tea tree oil is an antifungal remedy, but more research is needed to investigate the effectiveness of the oil. Before you incorporate at-home remedies to treat nail fungus, always check with your provider to see if these options are safe for you.

How to Prevent Nail Fungus

While it may be difficult to entirely avoid nail fungus, dermatologists recommend doing the following things to prevent getting nail fungus or having a repeat infection, including:

• Wearing flip-flops or shoes in shared, moist spaces, like pool decks, saunas, or gym locker rooms

• Throwing out and replacing any socks or shoes that you wore while having a prior foot or nail infection

• Changing your socks whenever your feet get sweaty

• Buying shoes that fit properly

• Preventing foot dampness by wearing leather, canvas, or mesh shows, which let your feet breathe more

• Alternating the shoes you wear each day

• Regularly cleaning and trimming your nails

• Sanitizing your nail clippers before use

• Avoiding using another person's nail clippers or wearing their socks and shoes

• Keeping the skin on your feet moisturized to prevent cracked skin and cuts

Complications

Though nail fungus isn’t dangerous and is often a cosmetic issue, there is a rare risk of developing some complications. These complications typically affect people older than 60 or those with weakened immune systems. Complications may include:

• Cellulitis: Fungi that spread from the nail to the surrounding tissues can cause cellulitis, an infection that causes swelling and discolored skin

• Sepsis: A serious and rare blood infection that can lead to shock and organ failure if the fungi infect your blood  

• Paronychia: Causing swelling, redness, and sometimes pus, paronychia is when the nail fungus spreads to the tissue folds around your nails

• Osteomyelitis: Occurs when the fungi spread to nearby bones, causing infection symptoms like pain, swelling, fever, and chills

A Quick Review

Nail fungus can develop when fungi enter the tissue below your nails, causing discoloration, brittle nails, and cracking. Walking on damp surfaces, sharing nail clippers with others, and wearing sweaty socks are some factors that can cause nail fungus. Fortunately, treatments like oral pills and topical medications can help reduce symptoms over time.

Frequently Asked Questions

Can you remove nail fungus yourself?

Generally, oral pills and topical creams are the best treatments for nail fungus. You shouldn't try to remove nail fungus on your own, but your healthcare provider may recommend over-the-counter treatments and trimming your nails to keep them healthy at home.

What kills toenail fungus permanently?

Researchers have found oral antifungal medications, such as Diflucan (fluconazole), Sporanox (itraconazole), and Lamisil (terbinafine), successful in clearing nail fungus almost 80% of the time.

What happens if you have toenail fungus for too long?

Advanced or long-term cases of nail fungus can cause worsening symptoms like cracked nails and thickened skin around the toenails. In rare cases, complications like cellulitis and sepsis can occur.

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