30 years old suddenly have fox odor, the etiology is not clear, may be related to certain factors, such as genetic factors, dietary habits, environmental factors, infectious factors, mental factors and so on. 1. Genetic factors: the prevalence will increase significantly if there is a parent who has a certain genetic predisposition to bad breath. 2. Dietary habits: usually love to eat spicy, love to eat stimulating food, will increase the chance of disease. 3. Environmental factors: for example, the outside temperature is too high, hot, humid, wearing clothes that are not breathable, etc., will also increase the risk of disease. 4. Infectious factors: local microbial infections can also induce bad breath. 5. Mental factors: mental tension, anxiety, emotional excitement, is also prone to increase the chances of morbidity. There may be other reasons why you suddenly have bad breath at the age of 30, so you need to go to the hospital in time and follow the doctor’s instructions for treatment.