Toenail fungus (onychomycosis) is caused by a group of fungi known as dermophytes. This group thrives on skin and on keratin, the main component of hair and nails. The fungus gets under the nail and begins to grow, damaging the nail so it discolors, becoming white, brown or yellow. Eventually, the nail might thicken, harden, become brittle and even fall off.
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.
Athlete's foot is a term given to almost any inflammatory skin disease that affects the sole of the foot and the skin between the toes. It is usually scaly and may be a red, raw-appearing eruption with weeping and oozing with small blisters. It affects the feet of athletes and non-athletes alike. Although it is frequently caused by a fungal infection, other causes may be indistinguishable without proper testing.

If the diagnosis is uncertain, direct microscopy of a potassium hydroxide preparation of a skin scraping (known as a KOH test) can confirm the diagnosis of athlete's foot and help rule out other possible causes, such as candidiasis, pitted keratolysis, erythrasma, contact dermatitis, eczema, or psoriasis.[13][23][27] Dermatophytes known to cause athlete's foot will demonstrate multiple septate branching hyphae on microscopy.[13]
If you observe any abnormal nail changes it is important to visit your doctor for prompt assessment. In addition to being cosmetically unappealing, OM can also lead to more serious complications, including the possible loss of your nail, bacterial infections, or cellulitis. Speak with your healthcare provider to determine what the best treatment plan is for you.
Dermatologists specialize in the treatment of skin disorders, including athlete's foot. You may find a board-certified dermatologist through http://www.aad.org. Additionally, family medicine physicians, internal medicine physicians, pediatricians, podiatrists (foot doctors), and other practitioners may also treat this common infection. Most primary care physicians can treat athlete's foot successfully.
The vesiculobullous type of athlete's foot is less common and is usually caused by T. mentagrophytes and is characterized by a sudden outbreak of itchy blisters and vesicles on an erythematous base,[7] usually appearing on the sole of the foot. This subtype of athlete's foot is often complicated by secondary bacterial infection by Streptococcus pyogenes or Staphylococcus aureus.[13]
Following effective treatment, recurrence is common (10–50%).[2] Nail fungus can be painful and cause permanent damage to nails. It may lead to other serious infections if the immune system is suppressed due to medication, diabetes or other conditions. The risk is most serious for people with diabetes and with immune systems weakened by leukemia or AIDS, or medication after organ transplant. Diabetics have vascular and nerve impairment, and are at risk of cellulitis, a potentially serious bacterial infection; any relatively minor injury to feet, including a nail fungal infection, can lead to more serious complications.[31] Infection of the bone is another rare complication.[6]
Infected nails are usually thicker than normal and could be warped or oddly shaped. They can break easily. Nails with fungus might look yellow. Sometimes a white dot shows up on the nail and then gets bigger. When fungus builds up under your nail, it can loosen and even separate the nail from the bed. The fungus can also spread to the skin around your nail.
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