Where Does Toenail Fungus Come From? Causes, Prevention and Treatment

Thick, yellow or crumbly toenails are something a lot of people hide under socks. Toenail fungus is very common, and it isn’t a sign that you’re not clean. It does tend to stick around, though, and it can spread to other nails. Here’s where it comes from, how to protect yourself, and which treatments actually help.

What causes toenail fungus?

Toenail fungus (the medical name is onychomycosis) is an infection of the nail and the skin underneath it. According to the Mayo Clinic, it’s caused by various fungal organisms, most commonly a type called a dermatophyte; yeasts and molds can also be responsible.

These fungi thrive in warm, damp places, which is why feet are such an easy target. Common ways people pick it up:

• From athlete’s foot. A fungal infection on the skin of the foot can spread into the nails.
• Damp public spaces. Locker rooms, pool decks and gym showers.
• Sweaty shoes and socks that keep feet warm and wet for hours.
• A nail injury, like stubbing a toe or tight shoes, that lets fungus get under the nail.
• Shared tools such as nail clippers, files, or unclean salon equipment.

Who is most at risk?

Anyone can get it, but the risk goes up with:

• Age, as nails grow more slowly and blood flow to the feet decreases
• Diabetes or poor circulation (see our diabetic foot care page)
• A weakened immune system
• Heavy sweating or a history of athlete’s foot
• Psoriasis or a past nail injury

Signs to look for

• A nail that’s thickened, yellow, brown or white
• Crumbly, ragged or brittle edges
• A nail that’s lifting away from the skin
• A slight odor, or discomfort in shoes

Other problems, such as nail injury or psoriasis, can look similar, so it’s worth getting a diagnosis before spending months on a treatment.

How to prevent it

• Keep feet clean and dry, especially between the toes
• Wear moisture-wicking socks and change them if they get sweaty
• Choose breathable shoes, and rotate pairs so they dry out
• Wear sandals in locker rooms, pool areas and public showers
• Don’t share nail clippers or files, and choose a salon that sterilizes tools
• Treat athlete’s foot promptly so it doesn’t spread to the nails

Treatments that work, and ones that usually don’t

Toenail fungus is stubborn because it lives under and inside the nail, where creams can’t reach well. MedlinePlus notes that over-the-counter creams and ointments usually don’t help treat it, while prescription antifungal pills, taken for about two to three months for toenails, are among the more effective options.

Depending on how many nails are involved and your overall health, treatment may include:

• Prescription oral antifungal medicine
• Prescription medicated nail solutions for milder cases
• Trimming and thinning thick nails in the office for comfort
• Laser nail fungus treatment, which we offer at Opensky Podiatry

Patience is part of the treatment. The American Academy of Dermatology explains that even when treatment works, it can take up to a year for a clear nail to grow out, and the fungus can come back. That’s why the prevention steps above matter after treatment too.

When to see a podiatrist

See a podiatrist if a nail is painful, thick enough to press in your shoes, spreading to other nails, or if you have diabetes or circulation problems. In those cases, a small infection can lead to bigger trouble. Learn more on our toenail fungus page.

Can I still get a pedicure?

It’s best to hold off at a salon until the infection is treated, both to avoid spreading it and to protect your nails. If you do go, bring your own tools and skip polish that traps moisture.

The bottom line

Toenail fungus comes from common fungi that love warm, damp feet. Over-the-counter creams rarely clear it, but prescription and in-office treatments can, especially when started early and paired with good prevention habits. Dr. Opensky sees patients in Skokie, IL and Whiting, IN.

Sources

• Nail fungus: Symptoms and causes. Mayo Clinic. mayoclinic.org
• Fungal nail infection. MedlinePlus, U.S. National Library of Medicine. medlineplus.gov
• Nail fungus: Diagnosis and treatment. American Academy of Dermatology. aad.org

This article is for general education and is not medical advice. If you have foot or ankle pain that isn’t getting better, or you have diabetes or poor circulation, see a podiatrist or your doctor.