Obsessive-Compulsive Disorder (OCD) is characterized by the presence of obsessions and compulsions. An obsession is a thought, urge, or image that is recurrent and persistent, intrusive and unwanted, and in most cases causes significant anxiety or distress. People with OCD will attempt to ignore or suppress the obsessions with some other thought or action (i.e., by performing a compulsion).

A compulsion is a repetitive behavior (e.g., hand washing, ordering, checking) or a mental act (e.g., praying, counting, repeating words silently) that the individual does in response to an obsession (e.g., to suppress the obsession). The compulsions are excessive and are done to prevent or reduce the anxiety or distress, or prevent some perceived dreaded event or situation.

The obsessions or compulsions are time-consuming or cause significant problems in social, work, or other important areas of functioning.

OCD is treated using cognitive behavior therapy (CBT), exposure response prevention (ERP), and often medication. CBT addresses the problematic thought patterns that may exacerbate symptoms and teaches alternative ways of thinking about situations. ERP directly addresses the obsessions and compulsions by safely helping the person face (or expose themselves to) the obsessive thought, urge, or image while refraining from engaging in the compulsion. This process works to desensitize the person to the anxiety-provoking nature of the obsession, and thereby reduces symptoms and time spent in OCD related thoughts and behaviors.