OCD Symptoms By Mayo Clinic staff Obsessive-compulsive disorder symptoms include both obsessions and compulsions. OCD obsessions are repeated, persistent and unwanted ideas, thoughts, images or impulses that you have involuntarily and that seem to make no sense. These obsessions typically intrude when you're trying to think of or do other things. Obsessions often have themes to them, such as: * Fear of contamination or dirt * Having things orderly and symmetrical * Aggressive or horrific impulses * amongst others