**7. Differential diagnosis**

There are many diagnoses that can be confused with OCD. For example, some anxiety disorders must be considered like generalized anxiety disorder, specific phobia, and social anxiety disorder. In generalized anxiety disorder, recurrent thoughts are usually about real-life concerns as finances and family, but in OCD these thoughts are irrational. Anxiety of patients with specific phobia is more limited with specific objects or situations, and they do not have rituals or compulsions. In social anxiety disorder, fear is limited with social situations. Major depression can be confused with OCD, but obsessions in major depression are usually appropriate with patients' mood, not intrusive or distressing and not related with compulsive behaviors. Some disorders that are under the category of OCD and related disorders like body dysmorphic disorder, trichotillomania, and hoarding disorder can interfere with OCD. In body dysmorphic disorder, obsessions and compulsions are only with physical appearance; in trichotillomania there are no obsessions, and compulsive behaviors are only hair pulling. Hoarding disorder patients have difficulty in discarding or parting with possessions. In consequence objects extremely accumulate, but in OCD obsessions are not typically related with dispose of objects. Although obsessions and compulsions in anorexia nervosa are limited to body image or weight, this disorder can be confused with OCD. Tic disorders also can be misdiagnosed as OCD. Tics are not related with neutralizing obsessions, and tics are less complex than compulsions. Not only OCD but also psychotic disorder patients can have irrational thoughts or delusional beliefs. But OCD patients do not have other psychotic symptoms and recognize that the intrusive thoughts are a product of their own mind. Obsessive-compulsive personality disorder does not have specific obsessions or compulsions but have a resistant perfectionist or controller personality structure. OCD can be confused with some medical conditions because of the results of compulsions like eczema, rashes, and constipation [8, 9, 84].
