Fentanyl is an opioid (opioid being a synthetic or semi-synthetic chemical compound that has the same agonist action at the mu-opioid receptor as the natural opiates, morphine and codeine).
Fentanyl is quite potent, it is 100x more potent than morphine as a mu-opioid receptor agonist. Thus the doses in pharmaceutical preparations are small -- a Duragesic patch
may deliver 25 to 100 micrograms of fentanyl (0.025 to 0.1 milligrams)per hour when worn.
It has the same effects as other opioids: analgesia (
pain relief), euphoria, sedation (but not sloppy sedation
like with
alcohol or benzodiazepines, there is little motor impairment except with very
high doses and one retains most of their social inhibition if they wish to not talk ... however...), increased DESIRE to talk to other
people (is another effect of opioids caused by the surge of dopamine released in the nucleus accumbens), itching, anxiolysis (relief from anxiety), and occasionally hyperproductivity and often enthusiasm / motivation (despite the sedative effect) due to the dopaminergic actions of opioids.
Fentanyl,
like other opioids, is one of the most intrinsically euphoric
drugs (opioids and psychomotor stimulants are the most intrinsically / non-set and setting dependent euphoric
drugs).
Fentanyl can be highly psychologically and physically addictive,
like other opioids.