Preventing DXM Nausea/Vomiting
To answer your question, ginger, 25-50 mg of DPH (active ingredient in Benadryl) , and antacid tablets (tums) taken 30 minutes before dosing are all really helpful for nausea. I also find breathing exercises and walking around on the come-up help. Some folks find moving around worsens the nausea, though.
If you take DXM polistirex you can perform a water extraction (just google "reddit.com: DXM water extraction") that eliminates almost all of the nausea.
Whether or not syrup or gels cause less nausea is kind of a personal thing. I find syrup is harder to get down but sometimes causes less nausea in the long run. Gel caps are easier to get down but in higher doses the gelatin can make the nausea worse.
If you're opting for DXM Hbr syrup, Robocough is going to be best for how little you need to ingest and the lack of additives.
If you do take DPH with your DXM, be sure to research its synergy and take a safe dose. IME 25-50 mg
We get this question all the time (not blaming you or anything, it's a good question) but the mods should honestly just the info to the r/DXM wiki.
---- a personal experience:
I had a traumatizing DXM trip (only 300 mg) where I completely lost control of my body and thought I was going to die. Finally, I threw up. Before that I also struggled with an eating disorder in my sophomore year of college and a couple other traumatizing drug experiences where I vomited.
Since that happened I just *can't* throw up in anything... The discomfort of stomaching it outweighs the reliving the experience, so I've spent a lot of time figuring out how to minimize it.