Niacin rhymes with:
eliason, eliassen, liason, liasson, mathiasen, mathiason, myosin, tobiason, acheson, addison, allison, amason, andreassen, comparison, dickason, diocesan, eliason, eliassen, fergason, fergeson, ferguson, fergusson, furgason, genemedicine, grieveson, hannesson, higgason, iason, jesudason, jonassen, liason, liasson, madison, magnuson, magnussen, magnusson, marcussen, markuson, matheson, mathiasen, mathiason, medicine, monessen, myosin, nicoson, ottoson, oveson, purgason, radisson, rasmuson, rasmussen, rasmusson, thomason, thomassen, thomasson, tobiason, unison, vargason, venison
Niacin sounds like:
nachman, nachmany, nagano, nagin, nakajima, nakama, nakano, nakashima, nakasone, nakayama, naquin, nashnamie, nason, nauseam, nazism, neeson, neisen, nesheim, nessen, neukam, neukom, new-mexican, newcom, newcome, newingham, newsham, newsman, newsmen, newsom, newsome, newson, newsum, newswoman, newswomen, nexgen, ngema, nguyen, niccum, nicen, nickeson, nickname, nickson, nickum, nicoson, niesen, nikon, nishimo, nishiyama, niskanen, nissan, nissen, nisshin, nissim, nissin, nixon, nizhny, noxema, noxon, nugan, nujoma, nukem, nusen, nuzum, nycum