Sudden fox odor in adolescence may be caused by not paying attention to hygiene, strenuous exercise or physical development. 1. not pay attention to hygiene: if the patient usually do not pay attention to personal hygiene, long-term not bathing, may make the local breeding bacteria, so that the sweat in the composition of the bacterial decomposition and metabolism, thus appear suddenly have bad breath. 2. Strenuous exercise: if the patient often do strenuous exercise, in strenuous exercise, sweat glands will increase the secretion of sweat, which is prone to the emergence of suddenly have bad breath. 3. Physical development: the occurrence of bad breath and the armpit area of the sweat glands, and their own metabolic level, hormone secretion, seasons and other highly correlated, puberty due to the physical development of hormone levels rise resulting in bad breath, the sudden onset of bad breath may be the development of the sweat glands to a certain level. The emergence of bad breath should go to the hospital in a timely manner, under the diagnosis of the doctor to choose the appropriate way of treatment, to avoid affecting the daily life.