Patients who suffer from dry mouth may benefit from using lemon glycerin swabs. However, they are not recommended for use over a long period of time. How Lemon Glycerin Swabs Work The lemon flavoring may over-stimulate the patient's taste buds. Lemon glycerin swabs work in relieving dry mouth in patients. The glycerin in the swabs is what stimulates the production of saliva. Glycerin is found in many household items and is believed to draw the moisture to the surface of the skin or in this case, the mouth. In addition to the glycerin, the lemon flavoring in the swab stimulates the taste buds to help in the production of saliva.