Obsessive-compulsive Disorder
People with OCD have obsessions—thoughts, images, or urges that the person ruminates over even though the person does not want them to. These obsessions intrude even when people are thinking about and doing other things. Obsessions typically cause distress or anxiety. The obsessions usually involve thoughts of danger, harm, or failure.
Because the obsessions are not pleasurable, people often try to ignore and/or control them.
They may do this by performing compulsions or rituals. For example, constantly washing one’s hands for fear of contamination.