Infection of the nails by fungus is called onychomycosis.
Onychomycosis can affect children and adults and is more common as people get older. The toenails are more commonly affected than the fingernails. When treated early, it is possible to cure onychomycosis. Onychomycosis can be caused by fungi, which commonly affect the skin, as well as unusual fungi.
Increasing age, the presence of tinea pedis (athlete鈥檚 foot), exposure to others who have onychomycosis, trauma to the nails, and a lowered immune system are common risk factors for developing onychomycosis.
Nails affected with onychomycosis can be thick, yellow, and crumbly. Sometimes there is a yellow streak in the nail that is caused by a collection of fungi. Sometimes just the top layers of the nail are infected with fungus. Less commonly, nails with onychomycosis can have a darker color.
The diagnosis of onychomycosis can be done easily. One common method is to send a nail clipping to a laboratory for a pathologist to examine with a microscope where they can see the fungi within the nail. Another common method to diagnose onychomycosis is with a fungal culture. This is done by lightly scraping material from under the nail and sending it to a laboratory. It is a good idea to have testing done to make sure that the diagnosis is correct, because other nail problems can look similar to onychomycosis.
There are multiple treatment options for onychomycosis, and the best choice will depend on the type of onychomycosis you have, as well as what you prefer. There are US Food and Drug Administration鈥揳pproved antifungal medications that come in topical and pill form. Topical medications, typically liquids applied to the nails, are the safest. However, they need to be used for a longer time and are not as effective as oral medications. Oral antifungal medications are more effective than topical antifungal medications but may have serious adverse effects. Topical and oral medications may also be used together to increase the chances of treating the fungal infection most effectively. It is also helpful to clip back any affected nails, because this removes infected nail and helps the treatment. If there is a yellow streak in the nail, a surgery to remove this area of infected nail may be needed. If there is a fungal infection on another part of the skin, such as the feet, in addition to the onychomycosis, this should also be treated.
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Published Online: April 10, 2024. doi:10.1001/jamadermatol.2023.5194
Conflict of Interest Disclosures: None reported.