So, I've been on Ondansetron for about... about a year or so, and in about 80% of the cases, the ondansetron (orally dissolving tablets) zapped the nausea within minutes. Other times, it took as long as 30-45 minutes.
I have noticed however, that I've been starting to take 8mg instead of the prescribed 4mg. It feels as if 4mg isn't making enough of a difference anymore as it used to. Should I seek out an 8mg prescription? These things already cost $18 (rounded up) at the given 4mg.
Before this, I was on Promethazine for a really, really, really long time. Promethazine helped at first, but eventually slowed down in effectiveness to the point that I was taking upwards of 60mg (I know, idiotic but my anxiety then was pretty powerful) before I felt any anti-emetic effect.
I do miss the calming feeling of promethazine–it seemingly helped with the anxiety more than the nausea, when the nausea wasn't strong.
tldr; Zofran doesn't seem to be working that strong anymore (promethazine experienced same effects). Do they lose effectiveness?