Obsessive Compulsive Disorder: What Causes OCD? Who Is At Risk Of Developing OCD?

Doctors aren't sure why some people have OCD and is more common in women than in men.

Obsessive Compulsive Disorder: Obsessive-compulsive disorder (OCD) is a mental illness. It causes repeated unwanted thoughts or sensations (obsessions). It can give an urge to do something over and over again (compulsions). OCD isn't about habits like biting your nails or thinking negative thoughts. An obsessive thought might be that certain numbers or colors are 'good' or 'bad'. A compulsive habit might be to wash your hands seven times after touching something dirty.