Lubricants were first used in clinical medicine to examine the human body, many medical devices will be in the human body, causing varying degrees of mechanical damage, and lubricants can minimize the damage to the body's tissues, mucous membranes.
Early human lubricants to glycerin and hydrophilic substances as the main components, and later improved to add sodium vitrate, ethyl cellulose, carbomer and other components, improved to reduce the viscosity, balanced pH, so that it is as similar as possible with the human body fluids, reducing the incidence of allergic symptoms.