Hot air coming out of the mouth all the time may be a normal phenomenon, or it can be caused by viral colds, burning mouth syndrome and other disease factors. 1. Normal phenomenon: If you eat spicy and stimulating food, or a lot of exercise, it may lead to hot air coming out of your mouth when you exhale, which is generally a normal phenomenon. 2. Viral colds: Hot air coming out of the mouth all the time may be caused by viral colds. Usually, patients with viral colds will have a generalized fever or respiratory fever, thus showing the phenomenon of hot air coming out of the mouth. 3. Burning Mouth Syndrome: The main symptom of Burning Mouth Syndrome is heat and burning pain in the oral mucosa, which also induces a series of oral inflammation, and therefore, the phenomenon of hot air coming out of the mouth may also occur. It is recommended that patients try to avoid spicy and stimulating food, exercise should also pay attention to the amount of moderate, if the symptoms have not been relieved, should go to the hospital in a timely manner, to clarify the cause of the disease, for treatment.