There are many causes of hot mouth, such as burning mouth syndrome, chronic inflammation of the tongue, lichen planus, Sjögren’s syndrome and so on. 1. Burning mouth syndrome: the main symptom of burning mouth syndrome is that the tongue will have obvious tingling, burning sensation, and some patients also have abnormal sense of taste, so the patient will feel hot in the mouth. 2. Chronic lingual inflammation: atrophy of the papilla of the tongue can also cause redness of the tongue, so there is the phenomenon of spicy mouth, usually the surface of the tongue is relatively smooth. 3. Lichen planus: Lichen planus of the oral mucosa will be accompanied by a burning sensation in the mouth, which will cause spicy mouth. 4. Sjögren’s syndrome: Sjögren’s syndrome can cause a decrease in the secretion of the tongue glands, so the oral mucosa will have a burning sensation, belonging to the autoimmune disease. There are many reasons for the spicy mouth, it is recommended that patients go to the hospital in a timely manner to improve the examination, a clear diagnosis, do not ignore the symptoms, so as not to cause adverse consequences.