Olfactory reference syndrome (ORS) is a psychiatric condition in which there is a persistent false belief and preoccupation with the idea of emitting abnormal body odors which the patient thinks are foul and offensive to other individuals. Olfactory reference syndrome (ORS) is a psychiatric condition in which there is a persistent false belief and preoccupation with the idea of emitting abnormal body odors which the patient thinks are foul and offensive to other individuals. People with this condition often misinterpret others' behaviors, e.g. sniffing, touching nose or opening a window, as being referential to an unpleasant body odor which in reality is non-existent and can not be detected by other people. This disorder is often accompanied by shame, embarrassment, significant distress, avoidance behavior, social phobia and social isolation. The term olfactory reference syndrome comes from: Although the existence of ORS is generally accepted, there is some controversy as to whether it is a distinct condition or merely a part or manifestation of other psychiatric conditions, mainly due to the overlapping similarities. Similarly, there is controversy with regards how the disorder should be classified. As ORS has obsessive and compulsive features, some consider it as a type of obsessive compulsive spectrum disorder, while others consider it an anxiety disorder due to the strong anxiety component. It is also suggested to be a type of body dysmorphic disorder or, as it involves a single delusional belief, some suggest that ORS is a monosymptomatic hypochondriacal psychosis (hypochondriacal type of delusional disorder, see monothematic delusion). The World Health Organization's 10th revision of the International Statistical Classification of Diseases and Related Health Problems (ICD-10) does not have a specific entry for ORS, or use the term, but in the 'persistent delusional disorders' section, states delusions can 'express a conviction that others think that they smell.' ORS has also never been allocated a dedicated entry in any edition of the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders. In the third edition (DSM-III), ORS was mentioned under 'atypical somatoform disorders'. The revised third edition (DSM-III-R) mentions ORS in the text, stating: 'convictions that the person emits a foul odor are one of the most common types of delusion disorder, somatic type.' The fourth edition (DSM-IV), does not use the term ORS but again mentions such a condition under 'delusional disorder, somatic type', stating 'somatic delusions can occur in several forms. Most common are the person's conviction that he or she emits a foul odor from the skin, mouth, rectum or vagina.' In the fifth edition (DSM-5), ORS again does not appear as a distinct diagnosis, but it is mentioned in relation to taijin kyōfushō (対人恐怖症, 'disorder of fear of personal interaction'). The variants of taijin kyōfushō (shubo-kyofu 'the phobia of a deformed body' and jikoshu-kyofu 'fear of foul body odor') are listed under 300.3 (F42) 'other specified obsessive compulsive and related disorders', and is about someone's fear that his or her body, or its functions, is offensive to other people. There are four subtypes of taijin kyōfushō. 17% of these individuals suffer from 'the phobia of having foul body odor', the subtype termed jikoshu-kyofu. Although taijin kyōfushō has been described as a culture-bound syndrome confined to east Asia (e.g. Japan and Korea), it has been suggested that the jikoshu-kyofu variant of taijin kyōfushō is closely related or identical to ORS, and that such a condition occurs in other cultures. However, some Western sources state that jikoshu-kyofu and ORS are distinguishable because of cultural differences, i.e. Western culture being primarily concerned with individual needs, and Japanese culture primarily with the needs of the many. Hence, it is claimed that ORS mainly focuses on the affected individual's embarrassment, and jikoshu-kyofu is focused on the fear of creating embarrassment in others. In this article, jikoshu-kyofu and ORS are considered as one condition. Synonyms for ORS, many historical, include bromidrosiphobia, olfactory phobic syndrome, chronic olfactory paranoid syndrome, autodysomophobia, delusions of bromosis, hallucinations of smell and olfactory delusional syndrome. By definition, the many terms which have been suggested in the dental literature to refer to subjective halitosis complaints (i.e. where a person complains of halitosis yet no odor is detectable clinically) can also be considered under the umbrella of ORS. Examples include halitophobia, non-genuine halitosis, delusional halitosis, pseudo-halitosis, imaginary halitosis, psychosomatic halitosis, and self halitosis. The onset of ORS may be sudden, where it usually follows after a precipitating event, or gradual.