Fentanyl is a very potent synthetic opioid and is a great pain reliever but it isn't exactly all that euphoric. The synthetic opioids are generally not as euphoric as the natural opiate and their immediate families (ie. morphine, diactylmorphine, nicomorphine, etc). The only synthetic opioids which I find very euphoric and very similar in effect to the naturals and semi-synthetics are pethidine/meperidine (Demerol) and some of its derivatives, levorphanol (Levo-Dromoran), piritramide, ketobemidone, dextromoramide (Palfium) and a few others.
