If I may ...
Ok. Just to clear this up. Heroin, synthesized from morphine, is illegal. Morphine and opium, both derived from the seedpod of the poppy plant, which derive codeine, hydrocodone (Vicodin), oxycodone, oxymorphone, hydromorphone, all from one plant are legal as long as you have a prescription. All these are true opioids on the list of controlled substances. Illegal on their own without prescription. Still ok to buy and own a firearm as long as you are "prescribed". Yet, cannabis, that of which is now being "legally prescribed", which has been proven, absent of course the blessing of US gov't and official US gov't sanctioned medical reports and testing [sarcasm], as safe after hundreds of years of use, will prevent you from buying or owning a firearm? Okey dokey.