Almost everyone has unpleasant or unwanted thoughts at some point, such as thinking they may have forgotten to lock the door of the house, or even sudden unwelcome violent or offensive mental images. But if you have a persistent, unpleasant thought that dominates your thinking to the extent it interrupts other thoughts, you may have an obsession. Some common obsessions that affect people with OCD include:

• fear of deliberately harming yourself or others – for example, fear you may attack someone else, such as your children
• fear of harming yourself or others by mistake – for example, fear you may set the house on fire by leaving the cooker on
• fear of contamination by disease, infection or an unpleasant substance
• a need for symmetry or orderliness – for example, you may feel the need to ensure all the labels on the tins in your cupboard face the same way

You may have obsessive thoughts of a violent or sexual nature that you find repulsive or frightening. But they’re just thoughts and having them does not mean you’ll act on them.