Scaly patches of skin produced by fungal or bacterial infection

When infections appear as rashes, the most common culprits are funguses or bacterial infections.

Fungal infections: Fungal infections are fairly common but don't appear nearly as often as rashes in the eczema category. Perhaps the most common diagnostic mistake made by both patients and non-dermatology physicians is to call scaly rashes "a fungus." For instance, someone with several scaly spots on the arms, legs, or torso is much more likely to have a form of eczema or dermatitis than actual ringworm (the layman's term for fungus). Likewise, yeasts are botanically related to fungi and can cause skin rashes. These tend to affect folds of skin (like the skin under the breasts or the groin). They look fiery red and have pustules around the edges. As is the case with ringworm, many rashes that are no more than eczema or irritation get labeled "yeast infections."

Fungus and yeast infections have little to do with hygiene—clean people get them too. Despite their reputation, fungal rashes are not commonly caught from dogs or other animals, nor are they easily transmitted in gyms, showers, pools, or locker rooms. In most cases, they are not highly contagious between people either.

Treatment is usually straightforward. Many effective antifungal creams can be bought at the drugstore without a prescription, including 1% clotrimazole (Lotrimin, Mycelex) and 1% terbinafine (Lamisil).