These disorders are characterized by the occurrence of repetitive behaviors, often called compulsions. Individuals with obsessive-compulsive disorder might engage in compulsive behaviors such as excessive washing, checking, arranging, or counting. Individuals with body dysmorphic disorder might engage in frequent checking of their appearance in the mirror, or excessive grooming-related behaviors. Individuals with hoarding disorder may engage in excessive acquiring of objects, combined with a strong need to save items. Individuals with trichotillomania engage in excessive hair pulling, and individuals with excoriation disorder engage in excessive skin picking.
In some cases, the obsessive-compulsive and related disorders are also characterized by intrusive, unwanted, or distressing thoughts, called obsessions, which come to mind again and again. People with obsessive-compulsive disorder might have obsessive thoughts about dirt or germs, thoughts of harming others, fears of making mistakes, or distress about things being out of order. People with body dysmorphic disorder have repetitive, negative thoughts about their own appearance. However, people with certain other obsessive-compulsive and related disorders (such as trichotillomania or excoriation disorder) often do not experience obsessive thoughts.