Primarily obsessional obsessive–compulsive disorder

Primarily obsessional obsessive–compulsive disorder, also known as purely obsessional obsessive–compulsive disorder (Pure O), is a lesser-known form or manifestation of OCD. It is not a diagnosis in the DSM-5. For people with primarily obsessional OCD, there are fewer observable compulsions, compared to those commonly seen with the typical form of OCD (checking, counting, hand-washing, etc.). While ritualizing and neutralizing behaviors do take place, they are mostly cognitive in nature, involving mental avoidance and excessive rumination. Primarily obsessional OCD takes the form of intrusive thoughts often of a distressing, sexual, or violent nature (e.g., fear of acting on impulses).

According to the DSM-5, "The obsessive-compulsive and related disorders differ from developmentally normative preoccupations and rituals by being excessive or persisting beyond developmentally appropriate periods. The distinction between the presence of subclinical symptoms and a clinical disorder requires assessment of a number of factors, including the individual's level of distress and impairment in functioning."