Athlete's foot is a form of dermatophytosis (fungal infection of the skin), caused by dermatophytes, fungi (most of which are mold) which inhabit dead layers of skin and digests keratin. Dermatophytes are anthropophilic, meaning these parasitic fungi prefer human hosts. Athlete's foot is most commonly caused by the molds known as Trichophyton rubrum and T. mentagrophytes, but may also be caused by Epidermophyton floccosum. Most cases of athlete's foot in the general population are caused by T. rubrum; however, the majority of athlete's foot cases in athletes are caused by T. mentagrophytes.
Patience is key, as treatment duration varies from 2-3 months for oral treatments to up to 12 months for topical treatment. Because the nails take a long time to grow (6 months for fingernails and 12-18 months for toenails), it will take some time for the infection to resolve and the nail appearance to improve, regardless of the type of treatment used. Sometimes treatment may not be successful and your doctor may prescribe a different medication.
Since some people are simply more prone to fungal infections, they are also prone to repeated infection. Preventive measures include keeping your feet clean and dry, avoiding prolonged moist environments, using socks in airport security lines, removing shoes, and allowing the feet skin to "breathe," avoiding walking barefoot, especially in public areas like swimming pools and gyms, avoiding contact with known infected people, and avoiding soaking and contaminated tool usage at nail salons. Weekly applications of a topical antifungal foot cream or sprinkling of antifungal foot powder (Zeasorb Foot Powder) into shoes may also be helpful.
There are many possible causes of foot rashes. Additional causes include irritant or contact dermatitis, allergic rashes from shoes or other creams, pompholyx (dyshidrotic eczema), psoriasis, yeast infections, and bacterial infections (gram negative toe web infection and erythrasma). Since these conditions are often indistinguishable on superficial visual examination, it is important for your doctor to do his best to identify the precise cause. Since fungal infections are potentially curable, it is important not to miss this diagnosis.