Cracked heels are a common complaint in women who go barefoot, wear sandals or poorly fitting unpadded shoes. A callous is a dehydrated keratin that is not shedding so that it becomes stiff and inelastic. When the foot moves, the keratin will crack into the living tissue, producing bleeding and pain.
Water is required by cholesterol sulfatase, which is the enzyme the makes our skin shed. The callous will not slough off until the skin is rehydrated. Urea and lactic acid are used to treat foot callouses since these chemicals will digest the keratin and open up water binding sites on the keratin, so that shedding can resume.
The safest way to remove a callous is to soak the feet in warm water with a few drops of liquid dish soap for 30 minutes prior to bedtime. Then, use your fingernails to scrape away the hydrated skin. Soak the feet for another 30 minutes and again remove the newly hydrated skin layer with your fingernails. Apply an exfoliating cream, put socks on, and go to sleep. In the morning, the callous will be well hydrated and easily removed with your fingernails.