The term “foot fungus” describes superficial fungal infections of the skin or toenails. Two of the most common foot fungi infections are tinea pedis and onychomycosis.
Tinea pedis is also known as athlete’s foot or foot ringworm, and it can affect the skin on the feet, causing itchiness and peeling or flaking skin. Onychomycosis is the medical term for fungal nail infections.
Keep reading to learn more about these two fungal infections, including potential causes, risk factors, and treatments.
All humans have fungi on their skin. These organisms are part of the microbiome, which is the complex collection of microbes that live in various parts of the body.
Usually, these microbes keep each other in check, and prevent any one species from growing too much. But sometimes, infections develop.
People may pick up an infectious type of fungi while walking barefoot. Alternatively, the fungi that is already on their skin or nails may become opportunistic.
Infections of the skin are often tinea pedis, also known as athlete’s foot or foot ringworm. If a person has a fungal infection of the nail, it is known as onychomycosis, or tinea unguium.
The fungi or other organism that cause these infections are:
Tinea pedis
Tinea pedis occurs due to dermatophyte fungi. These are fungi that require keratin for growth and can cause infections on the skin, hair, and nails.
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People can pick up these fungi while walking barefoot in places such as gyms, changing rooms, or swimming pools.
Onychomycosis
Fungal nail infections often occur when tinea pedis spreads to the nail, and so the same dermatophyte fungi that can cause athlete’s foot can also cause nail infections.
Occasionally, though, microbes that do not cause athlete’s foot infect a nail. Examples include yeasts such as Candida albicans and molds such as Scopulariopsis brevicaulis.
The risk factors for fungal infections of the feet include:
- having wet feet due to moisture, sweat, or humidity
- wearing enclosed shoes for long periods
- wearing synthetic materials on the feet
- using communal facilities such as swimming pools, showers, and baths
- having certain health conditions, such as diabetes or circulation problems
- having a compromised immune system
- involvement in certain sporting activities, such as expedition adventure racing
Fungal infections of the skin and nails have differing symptoms.
Tinea pedis
Tinea pedis can involve just one foot or both feet. It can present in one of three ways:
- itchy, peeling or scaly skin in between the toes, most commonly in the space between the 4th and 5th toes
- scaly skin on the sole and the sides of the feet
- small or medium-sized blisters on the inner part of the foot
In some cases, tinea pedis can occur in combination with a fungal infection of the groin, hands, nails, or both.
Other symptoms that a person with tinea pedis may experience include:
- moist, peeling skin
- an unpleasant smell
- thickening of the skin
- the skin discoloration, appearing white, yellow, or green
While uncommon, a person with tinea pedis may notice oozing in between the toes or ulcers forming.
Onychomycosis
Onychomycosis may involve one toenail or fingernail, or multiple nails. More commonly, onychomycosis affects the big toenail and the little toenail.
Symptoms of onychomycosis can include:
- a white or yellow streak on one side of the nail
- white spots on the nail plate
- scaling under the nail
- nail thickening
- the end of the nail lifting up
- discoloration of the nail
- damage or destruction of the nail
- a build-up of debris under the nail
- nail splitting
The diagnosis of both tinea pedis and nail infections typically starts with a physical examination. A doctor will check the foot for signs of either condition.
Next, the doctor may send skin or nail samples for testing. A scientist will check the scrapings of skin for spores to confirm the presence of fungi.
Treatment options for both infections may include:
Tinea pedis
Treatment for tinea pedis may include:
- topical antifungal cream
- salicylic acid, which may improve skin peeling
- tolnaftate powder to prevent reinfection after a person visits places where athlete’s foot may transmit, such as swimming pools
Typically, topical treatments work within
If topical therapy does not work, a doctor may prescribe oral antifungal medication, such as terbinafine or fluconazole. The treatment length and dose will depend on the severity of the infection.
Onychomycosis
Treatment for fungal nail infections may include:
- antifungal lacquer, which a person applies to the nail regularly
- topical antifungal cream or ointment
- ultrasound or laser therapy
- medical nail avulsion, which involves removing nails when the whole nail is affected
If topical options do not work, doctors may consider oral antifungal medications. The American Academy of Dermatology (AAD) state that antifungal pills have a higher cure rate than topical creams. They also work more quickly, so a person may only need to take them for a few months.
The AAD recommend the following to prevent tinea pedis or athlete’s foot:
- wearing sandals or flip-flops while in changing rooms, gyms, pools, or communal showers
- keeping the feet dry
- washing and drying the feet every day
- wearing socks made of natural fabrics
- alternating the shoes worn every day
- not sharing clothing or shoes with other people
Additional tips for preventing nail infections include:
- treating athlete’s foot promptly
- sanitizing nail clippers before use
- keeping the nails short by trimming them regularly
- moisturizing dry skin
Once the infection is gone, the AAD also recommends throwing away shoes a person wore during the infection to prevent recurrence.
Speak with a doctor or pharmacist about any signs of a nail or foot infection, such as itchiness or color changes.
This is especially important if they have a compromised immune system, or underlying conditions such as diabetes. Prompt treatment can prevent the infection from getting worse.
If treatments for fungal infections do not help, a person should contact a doctor for further advice.
Fungal infections such as tinea pedis and onychomycosis are widespread. Hot and humid environments and restrictive footwear encourage fungal infections.
A person should follow the recommended preventive measures to reduce the risk of infection.
If a person notices changes to the skin or nails of the feet, they should seek the advice of a medical professional to ensure early antifungal treatment.
