My friend is on codeine regularly (daily) for a persistent back injury. She’s worried that regular use and sometimes overuse of codeine can affect her liver, and cause damage. Is there any chance of this?
You are right to some extent about the reduced incidence of addiction when any of the opiates are used to control pain. However when physical pain lessens it is sometimes the case that people don't reduce the dose at the same rate. Often due not to pain but fear of the pain returning. In that grey area some start to experience the non- therapeutic effects and continue taking the drug for those entering the addiction phase and usually increasing the dose.