There are two major causes of fungal infections of the skin and nails: yeast and dermatophytes.
Yeast infections of the skin and nails are generally caused by an organism called Candida albicans. This organism normally makes a quiet home for itself on your skin and doesn't bother anyone. We all carry this organism on our skin (and in other places such as our mouth, our gastrointestinal tract (gut), and the vagina).
Occasionally Candida albicans multiplies uncontrollably, causing a yeast infection (also known as candidiasis). Yeast infections of the skin can cause a red, itchy rash that may leak fluid. Yeast nail infections can lead to pain and swelling, and may cause the nail to separate from the finger or toe.
Dermatophytes are fungi that only live in dead tissue, such as your nails and dead skin cells. Dermatophyte infections can also be called tinea. Dermatophyte infections of the skin can cause a round, scaly rash that may also have blisters. When dermatophytes infect the nails, the nails become thick, split, become dull, and may fall off.
Fungal skin infections may also be caused by a fungus called Malassezia. These infections, also called tinea versicolor, lead to scaly patches that vary in colour from white to brown.
Fungal infections may also affect the skin of the feet. This is also known as athlete's foot. For detailed information this condition, see the article on athlete's foot on this website.
Fungal infections may also affect the vagina. This is also known as vaginitis or female yeast infection. For detailed information this condition, see the article on vaginitis on this website.