The average age of onset for OCD symptoms is age 20. A small percentage of people have later onsets, for instance, past age 35. I had problems with OCD as a child. But I did receive treatment and have had no symptoms since I passed through adolescence. I am currently in my 30's.
Many patients report actually being free of the disease for up to many years.
It is very difficult to predict if a person with OCD at a young age will have the disease as an adult. However, when the disease passes adolescence into adulthood, the likelihood is that the person will have OCD through the life span. There are individuals with OCD who also engage in what we call self-mutilated behaviors. This is somewhat different, however, from harming obsessions. However, even with these individuals, most of the time the fear involves the possibility of harming others, or being responsible for contaminating others.