Obsessive–compulsive disorder (
OCD) is an 
anxiety disorder characterized by 
intrusive thoughts that produce uneasiness, apprehension, fear, or worry, by repetitive behaviors aimed at reducing the associated anxiety, or by a combination of such obsessions and 
compulsions. Symptoms of the disorder include excessive washing or cleaning; repeated checking; 
extreme hoarding; preoccupation with 
sexual, violent or religious thoughts; 
relationship-related obsessions; aversion to particular numbers; and nervous rituals, such as opening and closing a door a certain number of times before entering or leaving a room. These symptoms can be 
alienating and time-consuming, and often cause severe emotional and financial distress. The acts of those who have OCD may appear 
paranoid and potentially 
psychotic. However, OCD sufferers generally recognize their obsessions and compulsions as irrational, and may become further distressed by this realization