Obsessive compulsive disorder (OCD) consists of obsessions (repetitive, intrusive thoughts, urges, impulses or doubts) and compulsions (ritualistic, deliberate behaviours performed in response to obsessions). As well as contamination and safety fears, many patients experience distressing thoughts of causing harm. Sexual obsessions are common, including thoughts regarding sexual orientation, aggressive sexual behaviour or child molestation. Typical compulsions include checking, washing, ruminating, and counting.