The stinging of cosmetics, such as facial cleansers, when they enter the eyes is due to the irritation of the eye surface tissues, including the cornea or conjunctiva, caused by the chemical components inside. This phenomenon is similar to the irritation that usually occurs when dust or foreign objects enter the eyes, and the main symptoms are tearing, fear of opening the eyes, fear of light, and stinging pain. The chemicals in the face wash or cosmetics are soluble in water, and after it enters the eyes, with the irritation and tears, the eyes will produce a lot of tears, which will gradually wash away the chemical components on the surface of the eyes, and as these components are washed away, the irritation can be gradually relieved. In this case, the irritation can be relieved in a very short time.