The disorder causes people to have unwanted and repeated thoughts- feelings and ideas that make them feel driven to do something.
Howie Mandel is one of the many celebrities with OCD. He says he has a fear of germs and will not shake hands with anyone. Instead, he will do a "fist bump".
"OCD is real... I have a serious fear of germs and treatment helps me," Mandel said in a recent public service announcement. "If you know someone with OCD, talk to a doctor or therapist."
Mandel is not alone.
Actress Cameron Diaz is obsessive about cleaning doorknobs in her home, while Megan Fox has admitted her OCD has been a challenge. She has significant issues with public bathrooms and silverware in restaurants.
Award-winning actress Julianne Moore claims that her OCD helps with her roles when she plays dark and emotional characters. And Charlize Theron says she has to be incredibly tidy and organized. If not, it's difficult for her to function.
Actor Billy Bob Thornton is compulsive about mathematics. Howard Stern wrote a book in 1995 about his OCD and the impact it had on his education and career.
Even Donald Trump says he has borderline OCD.
Since OCD affects people differently, there are many ways to treat the disorder.
The Anxiety and Depression Association of America shares tips: www.adaa.org