Syndrome, Frey: Sweating on one side of the forehead, face, scalp, and neck occurring soon after ingesting food as a result of damage to a nerve that goes to the large saliva gland in the cheek (the parotid gland).
Frey syndrome is the most common cause of sweating after eating (gustatory sweating). Gustatory sweating is also a rare complication of diabetes mellitus in which case the sweating is on both sides of the head and the severity of the sweating may be mild or substantial.
This distressing problem can be difficult to treat. Treatments used include oxybutynin chloride, propantheline bromide, and clonidine. Recently, some success has been reported using topical applications of glycopyrrolate; the lotion was applied to the skin of the forehead and face, sparing the eyes and mouth.
"Gustatory" is a tasteful word. It means of or pertaining to taste or tasting. It is descended from the Latin "gustare," to taste.