i was given the gas in the time after i had the morphine injection and while we were waiting for the anesthetist to do his rounds on the ward and reach me to give me an epidural. i wasn't instructed on how to use it until just before the dr came in to do the epidural. i felt no affects from it, however i hadn't been sucking it correctly so for me, had no affect. ultimately i disliked it as it was another piece of puzzle that lead me to the caesarean