Take this carefully, since I dropped out/flunked from a Pharmacology MSc program in 1989. Here is a link to look at if anyone is interested, and then I'll explain some of my thoughts.
http://www.ncbi.nlm.nih.gov/pubmed/7904629
For about 4 years (before I started taking psychs on a regular basis as of February/2012) I knew a lot of people that would GI distress/upset as a result of using these classes of drugs. Acid reflux, stomach pains, gas, bloating, diarrhea and general GI distress
Well, as I said, I dropped out of Pharmacology in 1989, but always was aware/suspect of a relationship between H2 acid secretion and the dopaminergic system/receptor population (all the way from the stomach and on into the intestines. I've never just believed that 'mushrooms poison you' or that 'mushroom tissue was hard to digest'. I've been eating food mushrooms since I was ~10 yrs old.
When I started taking Cubensis mushrooms in February/2012 I would get horrible GI upset that would manifest well into the day after tripping. It felt like twirling razor blades in the stomach. And for me, 4-HO-DiPT acts like a poison and causes a 3 day sickness. 4-AcO-DMT had a somewhat similar effect, and the same with LSZ and AL-LAD (that's it. that's all the psychs I've taken)
I started taking an H2 inhibitor in order to combat the nausea/discomfort from mushrooms (Ranitidine; the only one I could get without a prescription) and it worked. Nausea, vomiting, gas bloating and stomachy discomfort gone. I took 75 mg approximately 1-2 hours before I would dose with a psych. I looked up the time to peak plasma level of the H2 blockers and decided on the 2 hour period.
I'm pretty sure that a lot of the psychs are stimulating acid secretion and *decreasing* intestinal motility. which was the cause of a lot of my discomfort.Ranitidine stimulates GI motility by increasing the amount of acetylcholinesterase available to bind smooth muscle muscarinic cholinergic receptors. It also stimulates colonic smooth muscle contraction in cats through a cholinergic mechanism.
Taking Ranitidine helped me greatly. The only other solution I had was to trip once a week on a regular basis and this would slowly lessen, but not eliminate discomfort. There's probably a good reason for this on a pharmacological basis, but like I said, I withdrew/flunked out. A 24 hour fast prior to dosing with a psych would also lessen problems, but I kinda like eating. I also think an extremely high fibre diet might help.
The link I've given is a reference to an abstract that would seem to support what I've said. It's pretty easy to pull up all kinds of scientific papers which show a strong dopaminergic influence on the digestive tract. Some of what I've posted is a copy/paste from stuff I've pulled of the net. Some of it is lecture material I sort of internalized almost 30 years agp
Some OTC H2 blockers are
Axid AR
Pepcid AC
Tagamet HB
Zantac 75 (this is the only non prescription one I can get)
So in my opinion it's not just acid secretion, but intestinal motility as well.
Tom
Transform - I don't know if you get this kind of stomach upset on Phenethylamines as well; I've never tried them and don't intend on it (hypertension on my end). I also take a beta blocker, calcium channel blocker and smooth muscle relaxer (these are prescribed) that keeps my hypertension well controlled. Hope this helps someone