NaOH – sodium hydroxide – is a white, solid compound also known as lye and caustic soda. Sodium hydroxide is a strong alkali and can cause severe chemical burns. Sodium hydroxide is widely used in many industries, including paper production, textiles, soaps, cosmetics, and chemistry. NaOH is included in many substances used to clear blockages in drains: it helps completely dissolve debris of all sizes and move it further through the pipes.