Malodor (halitosis/bad breath) has been a major concern for people through the ages. Despite the fact that odorless breath does not exist, we worry about other peoples’ reactions to our breath. Even if bad breath is purely physiological, the odor can intensify depending on a person’s health condition and levels of stress and anxiety. In some individuals, however, bad breath is caused by disease with no subjective symptoms. Because of the uniqueness of olfactory perception, it is difficult to assess the severity of one’s odor, which causes anxiety. Here, recognizing bad breath as an odor and manifestation of emotional stress, we discuss the management of bad breath and introduce the Japanese Academy of Malodor Syndrome Guidelines.