Athlete’s foot—the most prevalent foot fungus—thrives in warm, sweaty places like the insides of your athletic shoes, which is how it got its name. However, foot fungus can develop in multiple environments, natural and man-made, as long as there is lots of moisture where fungi can grow. These include shared areas at gyms or pools, soil and grass, or even shared items such as shoes, socks, or towels from household members who are infected.
Because athlete's foot may itch, it may also elicit the scratch reflex, causing the host to scratch the infected area before they realize it. Scratching can further damage the skin and worsen the condition by allowing the fungus to more easily spread and thrive. The itching sensation associated with athlete's foot can be so severe that it may cause hosts to scratch vigorously enough to inflict excoriations (open wounds), which are susceptible to bacterial infection. Further scratching may remove scabs, inhibiting the healing process.
Besides being exposed to any of the modes of transmission presented above, there are additional risk factors that increase one's chance of contracting athlete's foot. Persons who have had athlete's foot before are more likely to become infected than those who have not. Adults are more likely to catch athlete's foot than children. Men have a higher chance of getting athlete's foot than women. People with diabetes or weakened immune systems are more susceptible to the disease. HIV/AIDS hampers the immune system and increases the risk of acquiring athlete's foot. Hyperhidrosis (abnormally increased sweating) increases the risk of infection and makes treatment more difficult.
Nail infections occur more often in men than in women, and the infections are found in adults more often than in children. If you have family members who often get these types of fungal infections, you’re more likely to get them as well. Older adults are at the highest risk for getting fungal infections of the nails because they have poorer circulation and their nails grow more slowly and thicken as they age.
Trichophyton rubrum is the most common dermatophyte involved in onychomycosis. Other dermatophytes that may be involved are T. interdigitale, Epidermophyton floccosum, T. violaceum, Microsporum gypseum, T. tonsurans, and T. soudanense. A common outdated name that may still be reported by medical laboratories is Trichophyton mentagrophytes for T. interdigitale. The name T. mentagrophytes is now restricted to the agent of favus skin infection of the mouse; though this fungus may be transmitted from mice and their danders to humans, it generally infects skin and not nails.
The definition of over-the-counter (OTC) products means that they are available by ordinary retail purchase, not requiring a prescription or a license. Although there are few OTC medications aimed to treat fungal nails, many of these medications have not been tested and therefore are not approved by the U.S. Food and Drug Administration (FDA) for the treatment of onychomycosis. Most OTC agents are aimed at treating fungal infection of the skin rather than the nail. Some medications list undecylenic acid and/or propylene glycol as main ingredients. These ingredients inhibit fungal growth; however, they may not adequately penetrate the nail to be effective in treating fungal nails.
If the fungal infection has spread to the toenails, the nails must also be treated to avoid reinfection of the feet. Often, the nails are initially ignored only to find the athlete's foot keeps recurring. It is important to treat all of the visible fungus at the same time. Effective nail fungus treatment may be more intensive and require prolonged courses (three to four months) of oral antifungal medications.
Conventional treatment typically involves thoroughly washing the feet daily or twice daily, followed by the application of a topical medication. Because the outer skin layers are damaged and susceptible to reinfection, topical treatment generally continues until all layers of the skin are replaced, about 2–6 weeks after symptoms disappear. Keeping feet dry and practicing good hygiene (as described in the above section on prevention) is crucial for killing the fungus and preventing reinfection.
Removal of the nail can reduce symptoms rapidly, but regrowth of the nail can take one year during which time local treatment for fungus can be used. Oral medications include terbinafine (Lamisil), itraconazole (Sporanox), and griseofulvin (Fulvicin). Treatment regimens vary and can last between six weeks and one year. Side effects of systemic treatment include gastrointestinal disorders, liver toxicity, skin rash and other hypersensitivities. These medications should not be taken during pregnancy or if there is a chance you will become pregnant because of effects on the fetus.
For this treatment, the affected toe or finger first has to be soaked in warm water for ten minutes and then dried. After that, the urea-based cream is applied to the nail, and the nail is covered with an adhesive bandage. After 24 hours, the bandage is removed and the toe or finger is held in warm water again. The softened layer of the nail is then scraped off using a spatula, the cream is applied again and the nail is covered with a new bandage. This treatment is carried out over 14 days. Once the infected part of the nail has been scraped away completely, the skin beneath is treated for another four weeks with a bifonazole cream.
Fungi that are already present in or on your body can cause nail infections. If you have come in contact with someone else who has a fungal infection, it may have spread to you. According to the American Academy of Dermatology (AAD), fungal infections affect toenails more commonly than fingernails because your toes are usually confined to your shoes, where they’re in a warm, moist environment.
Athlete’s foot appears as a scaly red rash on the bottoms or sides of the feet often accompanied by itching, dry or cracked skin, stinging, and odor. You can also have moist, raw skin between your toes. Though athlete’s foot is fairly easy to treat with over-the-counter anti-fungal creams or sprays, this foot fungus is quite contagious and may easily spread to your toenails.
Wei, Y.-X., Xu, X.-Y., Xu, & Song, X. (2017). A review of antifungal natural products against the pathogenic fungi causing athletes' foot disease. Current Organic Chemistry, 21, 1–13. Retrieved from https://www.researchgate.net/profile/Xun_Song/publication/319128408_A_Review_of_Antifungal_Natural_Products_Against_the_Pathogenic_Fungi_Causing_Athletes'_Foot_Disease/links/59931c65458515c0ce61efa1/A-Review-of-Antifungal-Natural-Products-Against-the-Pathogenic-Fungi-Causing-Athletes-Foot-Disease.pdf