This mask is designed for very rough, thickened skin and deep-looking heel roughness, but it should only be applied to intact skin. If a heel crack is open, bleeding, painful, or looks like a wound, do not put the mask into that area. A 50% urea product is strongly keratolytic, meaning it helps loosen hardened dead skin; on broken skin it may sting strongly and increase irritation.
For heels with thick dry edges but no open wound, apply the mask only to the hardened surrounding skin and follow the contact time on the packaging. After use, remove softened skin gently with a pumice stone or foot file, then rinse. Avoid cutting calluses with blades at home, as it is easy to remove too much skin or create small injuries.
Do not use the mask between the toes, on the top of the foot, on inflamed-looking skin or on areas that feel unusually sensitive. Stop use if irritation appears. People with diabetes, neuropathy, reduced feeling in the feet or circulatory issues should consult a foot-care specialist before using high-strength keratolytic products, because small skin injuries may be harder to notice and manage safely.