 Unlike other KOR agonists, nalfurafine does not produce hallucinogenic effects in humans.Single intramuscular injections of up to 30 µg are well tolerated by humans, whereas a dose of 40 µg produced "moderate behavioral/psychological side effects" (possibly referring to sedation), though apparently did not produce any psychotomimetic or dysphoric effects.In rodents, a low dose of nalfurafine (10–40 µg/kg) was found not to produce conditioned place preference or aversion, though a high dose (80 µg/kg) did induce significant place aversion.