OCD is characterized by repetitive, unwanted thoughts and behaviors that control one's life in a destructive way. It is caused by overly active serotonin levels in the brain. Medications like SSRIs help control OCD by preventing serotonin reabsorption in the brain. Various therapies can also help reduce OCD symptoms, which include repetitive thoughts and actions, anxiety, and fears about consequences of not performing certain actions. OCD affects around 2.2 million Americans at some point in their lives.