I once had the WORST cough ever. Non-stop hacking for a week, exhausted I went to the doctor suspecting a bacterial infection. Sure enough he loaded me up with anti-biotics. Then said he was prescribing me cough medicine. I said, look here I have already wasted money on these useless over the counter cough medicines and proceeded to have a meltdown over the mere suggestion, being in a particularly foul mood already.
He said this isn't like the over the counter stuff. Got home, saw that it had codeine. Still fuming that I had spent even more money on cough medicine I took it as prescribed...wait for it...IT TURNED THE COUGH COMPLETELY OFF! I could not believe that, not after coughing like that for days on end.