Sodium sulfide is used in some over-the-counter foot care products to help soften thickened, hardened skin and the hardened nail edges that cause ingrown toenails, making them easier to lift and relieving pressure. It is an inorganic sulfur compound with strong skin-softening and keratin-dissolving properties, breaking down excess keratin around nail folds. However, it is alkaline and irritating, so it must be used with caution, avoided on broken skin, and should not replace professional medical treatment for severely infected ingrown toenails.