Obsessive-Compulsive Disorder is a condition that drives a person to perform a repetitive task or behaviour with the belief that by performing this ritual they will prevent harm to themselves or a loved one. A person suffering from OCD feels a responsibility to try to prevent bad things happening and perform the compulsive tasks to ensure this.
For someone without OCD it may be difficult to fully understand how such an intrusive thought can have such power over a person. So for an example think of the person you love the most, picture them in your mind. Now imagine if we tell you that without a shadow of a doubt, convince you beyond question, the door handle you just touched was touched by someone before who had just been to the toilet and not washed their hands. So your hand is now contaminated with deadly germs and unless you remove the germs you will pass them on to your loved one who will get a disease and die. We have convinced you that your hand is covered in deadly germs and so you may have become a little anxious, but even if you believed me, the anxiety would soon fade after you washed your hands. For someone with OCD that sense of anxiety will remain.
A normal response to an anxiety situation for someone without OCD is that the anxiety slowly decreases after the event or when removed from the situation but for someone suffering from OCD the anxiety remains or often increases after the event and starts the cycle of behaviours.
Hypnotherapy can help an OCD sufferer to recognise the negative cycle, work on reducing the stress and anxiety and the determine and remove the route cause of the behaviours.