Obsessive compulsive disorder (OCD) is a chronic mental illness characterized by unwanted obsessive thoughts and compulsive behaviors. It is thought to be caused by a combination of genetic and environmental factors like streptococcal infections. Common obsessions include fears of contamination, harming oneself or others, or forgetting important information. Compulsions are repetitive behaviors performed to relieve anxiety, such as excessive washing, counting, or checking. Treatments include antidepressant medication, exposure and response prevention therapy, stress management techniques, and support groups. At school, accommodations like extra time on assignments or testing in a quiet space can help students with OCD.