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Onychomycosis (toenail fungus) is an infection of the nail and sometimes surrounding tissue. It is extremely common with 20 percent of the general population and 75 percent of people over 60 years old affected. Frequently the problem causes cosmetic concerns, but many patients also experience pain. Sometimes toenail fungus can allow more serious infections to develop.
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.
Your physician may perform a simple test called a potassium hydroxide (KOH) preparation for microscopic fungal examination in the office or laboratory. This test can be used to confirm the presence of a fungal infection. This test is performed by using a microscope to examine small flakes of skin from the rash. Many dermatologists perform this test in their office with results available within minutes. Rarely, a small piece of skin may be removed and sent for biopsy or fungal culture to help confirm the diagnosis.

Sometimes people with a fungal nail infection are offered laser treatment. This involves shining infrared or ultraviolet (UV) light on the nail in order to kill the fungi. Laser treatments haven’t been proven to work in good quality studies. Because statutory health insurers in Germany don’t cover the costs of this treatment, people have to pay for it themselves.

Other risk factors include perspiring heavily, being in a humid or moist environment, psoriasis, wearing socks and shoes that hinder ventilation and do not absorb perspiration, going barefoot in damp public places such as swimming pools, gyms and shower rooms, having athlete's foot (tinea pedis), minor skin or nail injury, damaged nail, or other infection, and having diabetes, circulation problems, which may also lead to lower peripheral temperatures on hands and feet, or a weakened immune system.[11]
Toenail fungus is an infection that gets in through cracks in your nail or cuts in your skin. It can make your toenail change color or get thicker. It can also hurt. Because toes are often warm and damp, fungus grows well there. Different kinds of fungi and sometimes yeast affect different parts of the nail. Left untreated, an infection could spread to other toenails, skin, or even your fingernails.
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