Empathogenic NPS (or entactogens) are a class of drugs that produce experiences of emotional communion, oneness, relatedness, emotional openness. These NPS act like MDMA or ecstacy. These substance also have a stimulating effect and are therefore partly stimulants.
Examples are 4-FA, 5/6 APB and PMMA
Short term risk include mood swings, nausea, anxiousness, vomiting, overheating and risk of dehydration.
Long term risks include depression, dependancy. Not all long term effects are currently known
Empathogens are most commenly swallowed or snorted.
For more (fairly technical) information on the different empathogens, you can visit this Wikipedia page. Be aware though, that this page is not scientifically checked.