They include pathology of the right hemisphere of the brain, substance abuse, arteriovenous malformations in the brain, and temporal lobe epilepsy.Social anxiety disorder (SAD) and ORS have some demographic and clinical similarities. Where the social anxiety and avoidance behavior is primarily focussed on concern about body odors, ORS is a more appropriate diagnosis than avoidant personality disorder or SAD. Body dismorphic disorder (BDD) has been described as the closest diagnosis in DSM-IV to ORS as both primarily focus on bodily symptoms. The defining difference between the two is that in BDD the preoccupation is with physical appearance, not body odors. Similarly, where obsessive behaviors are directly and consistently related to body odors rather than anything else, ORS is a more appropriate diagnosis than obsessive–compulsive disorder, in which obsessions are different and multiple over time.ORS may be misdiagnosed as schizophrenia. About 13% of people with schizophrenia have olfactory hallucinations. Generally, schizophrenic hallucinations are perceived as having an imposed, external origin, while in ORS they are recognized as originating from the individual. The suggested diagnostic criteria mean that the possibility of ORS is negated by a diagnosis of schizophrenia in which persistent delusions of an offensive body odor and olfactory hallucinations are contributing features for criterion A. However, some reported ORS cases were presented as co-morbid. Indeed, some have suggested that ORS may in time transform into schizophrenia, but others state there is little evidence for this.
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 Organizations 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 Associations 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 that "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 persons 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").