Obsessive-compulsive disorder (OCD) is a type of anxiety disorder. If you have OCD, you have repeated, upsetting thoughts called obsessions. You do the same thing over and over again to try to make the thoughts go away. Those repeated actions are called compulsions.
Examples of obsessions are a fear of germs or a fear of being hurt. Compulsions include washing your hands, counting, checking on things or cleaning. Untreated, OCD can take over your life.
Researchers think brain circuits may not work properly in people who have OCD. It tends to run in families. The symptoms often begin in children or teens. Treatments that combine medicines and therapy are often effective.
NIH: National Institute of Mental Health
For more information, go to http://www.nimh.nih.gov/health/publications/obsessive-compulsive-disorder-when-unwanted-thoughts-take-over/obsessive-compulsive-disorder-when-unwanted-thoughts-take-over.shtml