What is addictive about pain killers (pain killer addicts help me out)?

Different painkillers affect the body in different ways in order to lessen the pain, some are opiates which not only relieve the body of pain but also give you a feeling of happiness and relaxation in your brain. The most popular drug at the moment is the painkiller oxycodone I know how it feels when you take this as I had a bad accident a few years ago and broke my back and I have had a few operations. It is a wonderful feeling like you are completely comfortable and you have no worries in the world and someone you love is giving you a big warm hug. Not only do you feel great but there is no hangover or comedown the next day that is why so many people become addicted.