Intrusive thoughts are an unwelcomed involuntary thoughts, images, or unpleasant ideas that may become an obsession, are upsetting or distressing, and can feel difficult to manage or eliminate.

When such thoughts are associated with obsessive-compulsive disorder (OCD), depression, body dysmorphic disorder (BDD), and sometimes attention-deficit hyperactivity disorder (ADHD), the thoughts may become paralysing, anxiety-provoking, or persistent.  Intrusive thoughts may also be associated with episodic memory, unwanted worries or memories from OCD, post traumatic stress disorder, other anxiety disorders, eating disorders, orpsychosis.  Intrusive thoughts, urges, and images are of inappropriate things at inappropriate times, and generally have aggressive, sexual, or blasphemous themes.