What causes harmala alkaloïds to induce vomiting?

it could be that it induces a form of motionsickness. Unfortunately some people are just more susceptible to that than others. Datura seeds help a bit against motionsickness but antihistamines are not to be combined with MAOI's because they can have severe side-effects.
I find that hallucinogenic tryptamines themselves also hugely reduce motionsickness so maybe smoking some DMT the moment you feel it coming, could help.

It could also be that it's not a motionsickness-like phenomenon but just the direct effects of harmala's on the stomach. I find that harmala's have a quite a bit of an anasteatic effect: put them on your tongue and it will get numb immediately. It could definately be that the stomach perceives harmala's as toxic, just like alcohol.
In that case you could maybe reduce the effect by gradually increasing the dose of ingested harmala's instead of taking them at once, reducing the 'toxic shock', but i wouldn't know how much the period of intake could be stretched. You can't wait for too long either.

I have found recently that pure harmalas when swallowed are WORSE than caapi or rue tea when properly filtered and decanted..I think the teas are just less harsh becasue the harmalas are in ratio with the liquid or sugars etc in the brew..pure harmalas in hcl form make my mouth numb also polytrip and I have noticed some uncomfortable stomach effects when I ingest them that I dont get with rue or caapi tea. I still like to eat them though sometimes.

Our group this past weekend had great success with ginger tea. Pretty much everyone agreed that it helped with the nausea and not a single person purged...though I did feel nauseated for about 15 minutes or so.

BTW 3g of MHRB is an extremely week dose for aya, but it was a good starting point. Next time without a doubt I'm going 6-8g. I'll probably bump the harmalas up from 50g to 75-100g as well. All in all I have to say I really enjoyed the low dose Aya experience. The harmala body load is actually very pleasant once the nausea goes away.

peace.

depending on the ammount of harmalas 3g can either put me in hyperspace or just me a mellow DMT glow. I have had large doses of caapi followed by just 2 grams of mimosa than had me flipping out in the dark at how much I was hallucinating.

50g of caapi with 3g mimosa is not going to be too heavy in my experience..100g of caapi with 3g of mimosa might have you on your ass though so be careful..I would not double the mimosa dose if you are also upping the caapi..everyone is different..just keep in mind that for me once I hit a certain saturation point with the harmalas, what was once a light dose of mimosa can get very hyperspacy all of a sudden..6-8g of mimosa is way way too much for me. I dunno when I will ever take that much again

some people might need 8g though. I know people who need to eat like 5-6g of cubes to get to where 2-3 will take me so go figure..

This is good advice. Thanks for this. From an economics point of view it would seem to make more sense upping the MHRB dose...but from an afterglow experience I'm betting it's adding more caapi. Caapi is just flat out expensive because of the quantities we have to consume...and it doesn't sound like rue is a great alternative from reports I've read.

well, I really like rue alot and have been using it lately..I drank 3 grams of rue with 3 grams of mimosa the other night and I still feel really good..the rue was brewed 2 months ago and filtered and then decanted after like a month becasue I dont want any rue sediments in my brews..

I still drink caapi ayahuasca once a week though and dont use harmala seeds as a replacement..I just really like both of them..they are very similar IME but there are some subtle differences as well..I have combined rue and caapi also and it was nice.

Upping the caapi dose does make for a stronger purifying feeling and resulting afterglow I find..but caapi is $$..minxx and I just order 2 kilos at a time because smaller ammounts are just not worth it for how often we drink..if you are not far enough after an hour or so with the first dose you can always drink more as well and it will increase the effects, it does for me at least. Often times the second cup even 2 hours later is alot stronger than the first.

So Rue still has this poor reputation eh? As fractal said, they are pretty similar. I have found Rue to be more sedating than caapi, which may lend itself to being LESS "intense" than caapi. Both will run through your body and mind like a dragon if you take enough. But the stimulating effect of caapi alkaloids may cause ones mind to feel like it's exploding out of control. On the other hand, rue may lend itself more to a sense of oceanic consciousness.

I would actually invest in Syrian Rue stocks, if such a stock exist, and if I knew anything about investing. I think more people are going to realize they can get a lot of good harmalas from much cheaper rue, and rue is going to gain much popularity around the world. Only problem is if more countries make it illegal. In that case, obviously, the investment would fail.

Failure depends on how you describe success. At least you'd have a whole lotta rue!

I've also tried ginger, dramamine, smoking weed, chewing mint and at best (or worse depending on perspective) it just makes me nauseous but prevents me from being able to vomit. Nausea being one of those most unsettling sensations on the planet can really ruin an experience for me, so I subscribe to trying to vomit everything up which usually gets rid of all the nausea. Many times I can't get everything up though so the nausea will return. My remedy to this is that as soon as I've gotten myself to purge once (I usually aim for the one hour mark), regardless of whether I'm nauseous or not, I usually like to break out the GVG afterwards. Assuming I got everything up, then no harm no foul. If I hadn't gotten everything up, then 1-2 rips of a small dose out of the GVG is enough to completely flood the system with DMT sending the nausea levels through the roof, and I'll be damned if I've ever had persistent nausea after taking the hit or two. From there on out I'm nausea free for the rest of the day, and should I decide to smoke more DMT later, it never results in any nausea at all. I use the vaporized DMT as a sort of chemical trigger to my gut which seems to do the trick. The purging itself is by no means pleasant, though I've had some of the most interesting, twisted visuals one can imagine with my eyes winced shut as my intestines proceed to continually turn themselves inside out. Luckily afterwards, by the time I shuffle back to my couch, I'm on cloud 9.