Caustic cleansers are cleaning agents that contain lyes, which are highly alkaline substances such as sodium hydroxide or potassium hydroxide. These substances are used to remove dirt, grease, and other organic matter from surfaces. They are often used in industrial settings, but can also be found in household products such as oven cleaners, drain cleaners, and toilet bowl cleaners. Caustic cleansers are effective at removing tough stains, but should be used with caution as they can cause skin irritation and damage surfaces if not used properly.