I have enough experience now to do a somewhat controlled comparison between DXM hydrobromide and polistirex (Delsym). Same nominal dose, different experience. Here are my observations.
Trial A: DXM HBr, 300mg (I’m 80kg = 3.75mg/kg)
Onset: First effects at T+40min, clear plateau reached by T+1:15. Intense and fast-rising. Peak was sharp — very obviously peaked and then obviously declining. Duration to baseline: about 7 hours. Clear beginning, middle, end.
Trial B: DXM Polistirex, 300mg nominal
Polistirex’s bioavailability is approximately 75% that of HBr, so this was effectively closer to 225mg HBr equivalent. But the extended-release profile changes everything.
Onset: Nothing until T+90min. I almost convinced myself it hadn’t worked. Then it started, slowly and incrementally. No sharp takeoff.
Peak: Gentler plateau, significantly longer. Seemed to plateau around T+3:00 and stayed there for what felt like several hours. Less intensity than equivalent HBr but much, much longer tail.
Duration: Effects were still present (though very mild) at T+12. I would not have wanted to have obligations the next morning.
Which Is Better?
Neither is objectively better — they’re genuinely different experiences. HBr is sharper, shorter, more intense. Polistirex is slower, gentler, longer. For music sessions or creative days: polistirex. For evenings only where you need to be functional the next day: HBr.
Key warning: Polistirex’s slow onset is a TRAP for impatient redosing. Wait at least 3 hours before concluding it hasn’t worked.