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Though unsightly, calluses are usually not a problem. Ones that form on your hands if you play tennis, or on your fingers if you play a string instrument, can actually be helpful. But if a blister forms underneath or if calluses become too thick and crack, they can be painful. Calluses that develop a thick center are called corns and usually develop on toes, where they are particularly tender.
If you get hard calluses on your feet, use a pumice stone regularly after showering or soaking your feet in warm water, and apply a thick moisturizer daily. If they are painful or bothersome, a podiatrist can trim down the thickened area with a blade (never cut a callus yourself), prescribe a cream or ointment, and help identify and correct what may be causing them. Besides wearing properly fitting shoes, you may be advised to use shoe inserts, especially if you have an underlying foot problem. If you have diabetes or a nerve or circulatory problem that affects your feet, seek medical attention for problem calluses.
Ointment options: Prescription creams and ointments containing urea or lactic acid, at 40 to 50% strength, are most effective. Called keratolytic agents, they chemically break down and soften the thick skin of the callus. Over-the-counter products often contain the same (or similar-acting) chemicals as prescription products, but at lower concentration, so they may be less effective or not effective at all. Those containing salicylic acid may be harmful if not used correctly, so follow label directions carefully. Some over-the-counter creams contain "patented enzymes," plant oils, or other "natural exfoliating" ingredients, though it's doubtful that these help at all.
Beware of eggs and corn cutters. The Ped Egg, advertised in infomercials and on the Internet, is the latest in callus-care products. Shaped like an egg and resembling a cheese grater, it contains numerous stainless steel microfiles that file away the callus. It costs under $20 and comes with plenty of testimonials, but if you scrape too hard (as with a pumice stone, too) or use it on wet skin you can end up abrading healthy skin and risking infection. Use it cautiously or not at all if you have diabetes or circulatory problems. Especially risky is the Credo corn cutter (and similar products), sold in many drugstores, which uses a razor blade to shave off calluses, but can easily slice off an entire layer of healthy skin underneath. Our credo: avoid the Credo.