Burning mouth syndrome (BMS) is currently defined by the International Headache Society (IHS) in the International Classification of Orofacial Pain, ICOP and in International Classification of Headache Disorders, ICHD 3 as “an intraoral burning or dysesthetic sensation, recurring daily for more than 2 hours per day over more than 3 months, without evident causative lesions on clinical examination and investigation”. In the International Classification of Diseases, ICD-11, BMS is “chronic burning mouth” in the primary chronic headache and orofacial pain disorders. Previously used terms are stomatodynia, glossodynia, and primary BMS. In approximately 2/3 of the patients, taste alterations and dry mouth may occur, giving reasoning to consider the symptom complex a syndrome. In the ICOP classification, two subtypes of BMS are recognized: BMS with or without somatosensory changes. As somatosensory alterations may occur due to changes either in the peripheral or central nervous system, this subdivision does not define the origin of possible neurogenic alterations