yea, you could just have a natural tolerance to opiates like me. That amount of codeine has NEVER been able to anything to me. Or you could have been using other stronger opiates and just not told us about it....meaning you have an opiate tolerance we dont know about. IM sry, its just that some people really dont think to tell people that information when they ask these kinds of questions. Or, like they said, you could be one of the few people who cant break codeine down into morphine. I would take like 20 mg's of hydrocodone and see if you feel anything. if you do, then you probably just cant properly digest the codeine because if 400mg's of codeine wont get you high because of a toelrance, then neither would 20mg's of hydrocodone.