I've gotten it from the freebase but not the HCl. Thing is, my use of the freebase occurred between 4 and 6 years before I first started using the HCl, and the HCl is all I've used since with the exception of a few doses of aMT acetate used rectally (no nausea). Plus the HCl is done almost exclusively IM, though my one 50 mg oral dose was nausea free. It's impossible to know the factors responsible for the lack of nausea given the separation in time (maybe my physiology changed), and I'm not about to eat a bunch of freebase to find out.
In addition to the poll, I think one way (a dirty and informal but still recommendable way) to go about this is to do a ghetto content analysis of Erowid general reports that are highly rated. General reports are ostensibly about the use of a substance in isolation, and the higher rated reports (star system/order from the top of the vault page [though order is also effected by date of submission I think]) tend to be more descriptive. So you could just take the top 20 (more is better) or so general reports for aMT and a random-ish selection of the top 20 from a bunch of other psyche vaults and do ctrl F searches for nausea and its synonyms in each report (there's a better way to do it with Google Analytics or something no doubt, but this is just to illustrate something anyone could do). Then you just compare the proportion of aMT reports where people mention getting nauseated to the average proportion of all the others (which represent "proportion of nausea reports from X number of different non-aMT psychedelics"). I don't think you'd have to worry about statistical significance for this shizz. Aaa... but I'm not gonna do it (might do it for one psyche vault -- community project!).
I think it's likely aMT reports would show more incidences of nausea just based on my memory of reading lots of different reports. Other substances that stand out in memory: 5-MeO-aMT (many 5-MeOs actually, but it's the worst); mescaline (even pure); 2C-T-7; and, HBWR seeds.
Since many of these psychedelics come on slower than average and are regarded as more gentle or less radical psychedelics at typical doses I'm not sure how well the theory that tension/adapting to new state of consciousness is the cause of nausea works as a primary explanation. I don't doubt tension plays a role and can be sufficient to cause nausea in some cases, I just don't think it's the single largest cause -- insofar as it's sensible to talk of "single" causes in biology/pharma (I think the largest cause is lost somewhere in the mysterious pharmacology and kinetics of these specific problem drugs as it relates to the mysterious causes of nausea). The reason I think this is that from the rising tension perspective wouldn't we think that the more abrupt the onset of a psychedelic is, the less time we have to adjust to the tension, and therefore the more likely it is to cause nausea? This would predict that drugs with faster onsets, as well as ROAs with faster onsets, will have higher direct correlations with nausea than others. I don't think that's generally the case (smoked DMT and salvia not usually causing nausea, the use of rectal admin to avoid nausea despite being a faster route than oral, etc.).
