What risk do you take by taking growth hormones at the age of 15?

If it is prescribed by a physician I don't think there should be a problem. Many years back there might have been as it was taken from people who may have died of brain problems, but nowadays it is synthetic so you cannot catch anything. If you are taking it at the gym to 'bulk up' I believe it is illegal and as you cannot be sure of the source it could be dangerous as well.