Toenail Fungus: What to Know About Symptoms, Causes, and Treatment Options, According to Experts

It might seem like a harmless problem, but doctors say you shouldn't ignore this fungal infection.

For the most part, toenails don't get a whole lot of love. Sure, you trim them every now and again; maybe you even paint them a bright color in the summer. But toenails are one of the more uninteresting parts of our anatomy, and it's safe to assume hardly even think about them—until there's a problem.

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Other than the usual bumps and bruises (admit it, you've stubbed a toe on your coffee table before), one of the most common issues people have with their toenails is fungal infection.

Like it or not, we spend our days living among a host of microorganisms, including fungi and yeast. Many of these organisms never make themselves known to us, peacefully coexisting in, on, and around our bodies. But some of them have a tendency to overgrow, causing infection and a whole bunch of symptoms, from painless itching to funky odors.

This is exactly what happens when you're dealing with a bout of toenail fungus. Here's what you need to know about the different types of fungal toenail infections, what causes them to occur, and what you can do to treat them.

What is toenail fungus?

Toenail fungus, also called onychomycosis, is the umbrella term for a handful of microorganisms that can infect one or more of your toenails, according to the Centers for Disease Control and Prevention (CDC). The infection is typically the result of a superficial cut, crack, or opening near your toenail; with this window of opportunity, the fungus is able to sneak in and spread, causing an infection.

Infections can range from mild or barely noticeable to severe, affecting multiple toenails and causing pain or deformation of the nail.

Are there different types of toenail fungus?

There are three different types of toenail fungus, William Spielfogel, DPM, director of the Podiatric Medicine and Surgery Residency Program at Lenox Hill Hospital-Northwell Health, tells Health. They include: distal subungual onychomycosis, white superficial onychomycosis, and candida onychomycosis.

We're going to simplify that for you, though, by telling you that molds and yeast are basically always to blame.

One type of mold, known as dermatophytes, only grows in keratin-producing structures like hair follicles and nails, Ashley Jenkins, MD, a dermatologist at University of Missouri Health Care, tells Health. This is distal subungual onychomycosis, and Dr. Jenkins says it's responsible for at least 60% of toenail infections.

Another type of mold, white superficial onychomycosis, is a non-dermatophyte—that means it starts by infecting the top layer of the nail rather than the follicles. And finally, candida onychomycosis is caused by yeast overgrowth—this is the least common type of toenail fungus, but it does happen.

What does toenail fungus look and feel like?

There is a range of symptoms that can occur with any toenail fungal infection, but some of the most common ones include:

  • Nail thickening
  • Yellowing, browning, or discoloration
  • Nail crumbling
  • Abnormal or frequent breakage
  • Unusually shaped nails
  • Separation of nail from the nail bed
  • Pain
  • Odor or bad smell

Different types of infections often cause different symptoms. For example, many mold infections aren't very painful but yeast infections can be; similarly, you may notice a dark build-up of debris under the nail with distal subungual onychomycosis, but you're more likely to see white spots or patches on the surface of the nail with white superficial onychomycosis.

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What causes toenail fungus?

We come into contact with the yeast and molds that cause toenail fungus frequently, but there are a number of reasons why an infection might occur. Typically, people with cracks in their toenails or with weakened toenails are most at risk—this means older adults, people with superficial toe injuries, and people with certain skin conditions, like psoriasis.

Dr. Jenkins says there are some other common risk factors for toenail fungus, too, including having diabetes, a history of athlete's foot, or a suppressed immune system (either because of an autoimmune condition or from being on immunosuppressant drugs). "If fungus is hanging around [under these circumstances]," she adds, "it will crawl underneath the nail and spread."

You may also be at a higher risk for toenail fungus if you:

  • Wear poor-fitting shoes
  • Have poor circulation
  • Sweat more than usual, especially from your feet
  • Are male
  • Are a smoker
  • Spend a lot of time in the water or walking in damp areas (like an indoor swimming pool)

How to get rid of toenail fungus

First, the bad news: Dr. Jenkins and Dr. Spielfogel both admit that toenail fungus is extremely hard to treat, especially at home.

"The most effective treatment is an oral systemic antifungal medication, such as Lamisil, once per day for 12 weeks," says Dr. Jenkins. "It cures around 75% of patients, but 25% won't be cured and will need repeat treatment or even a surgical treatment, like removing the toenail."

For the most part, Dr. Jenkins says Lamisil is generally safe for use, though it can—in rare cases—cause liver enzyme abnormalities. She adds that this side effect is almost never seen in children, and that your doctor will monitor these enzymes and perform frequent blood work during your course of treatment to ensure Lamisil is not negatively affecting your liver.

If you're still concerned about Lamisil as a treatment option or you have an existing medical condition that prevents you from safely taking it, your doctor may prescribe a topical treatment instead...but those take a lot longer to work (think 48 weeks, i.e. almost a whole year) and only have a 25%-30% cure rate.

Finally, you can try a home remedy for toenail fungus—while most of them aren't terribly effective, they don't come with many side effects, either. If your toenail fungus is mild, you might be able to see results over time.

"[Home remedies] have maybe a 10% cure rate, but could be effective enough if someone is highly motivated," says Dr. Jenkins, who adds that some of her patients swear by frequent applications of products such as Vicks VapoRub, amber-colored Listerine, and tea tree oil.

If you're going to attempt an at-home remedy, it's important to give your toenail some extra TLC, says Dr. Spielfogel: "Keeping the area clean and dry may help keep the infection under control."

Can you prevent toenail fungus?

If your toenail fungus is caused by something in your control (i.e., not an underlying condition), then yes. You can:

  1. Wear shoes in public areas, especially ones that are typically wet, like pools and gyms.
  2. Keep foot injuries clean and covered until they're healed.
  3. Protect your overall health by not smoking and maintaining a healthy weight.
  4. Wear supportive and breathable shoes.

You also may see a reduction in bouts of toenail fungus by keeping your toenails consistently clean, dry, trimmed, and free of nail polish (which can clog the nail and contribute to fungal growth).

However, many causes of toenail fungus are caused by other conditions, like chronic illness, old age, and diabetes, and there may not be much you can do to prevent fungus in these situations. Dr. Spielfogel does recommend using preventative products if you know you're at risk for fungal infections; the Dr.'s Remedy line of nail care products, for example, includes an antifungal cuticle oil that can be used nightly to reduce the risk of fungal growth.

When should you see a doctor?

It's tempting to dismiss toenail fungus as an unsightly but mainly harmless problem. Like so many other health issues, though, ignoring it will only make things worse down the line.

"You should see a podiatrist when you notice the problem and treat it early," advises Dr. Spielfogel. "If left untreated, which is very common, the infection will spread to the rest of the nail and eventually spread to the other nails."

Once you make an appointment, your podiatrist will give your feet a thorough examination and will probably take a biopsy, or sample, of your nail to be sent away for testing. This will help your doctor confirm that you have an infection and not some other issue, as well as figure out exactly what type of infection you have, Dr. Spielfogel explains.

From there, your doctor can work with you on a treatment plan to (hopefully) get rid of your toenail fungus for good.

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