There is probably a typology of negative trips, but obviously very little science has been done on it. My (inter)personal experiences identify a few distinct culprits, perhaps amongst many, or perhaps all a naive fiction i've constructed for myself:

1. Overstimulation, an inability to cope with all the new perceptions. This is especially pertinent during come-up. If you experience overstimulation in sober life, you'll probably recognize it. If you haven't, it feels like agitation and confusion.

2. Anxiety that is brought into the trip that is either consciously perceived or not beforehand. If something's bothering you at the back of your mind, it's going to come up front and center.

3. Intrusive thoughts. There's no reason why they can't happen on a trip, right? Like sober life, the best thing that makes them go away is acknowledging them and letting them play out. Trying to force them down can make them worse. Intrusive thoughts can lead to disturbing experiences even if they don't result in a bad trip.

4. Panic from feeling your own body in unfamiliar ways. Your proprioception shifts rapidly with LSD. You might not be able to tell where your limbs are, or whether they even still exist. The solidity of your body suddenly feels a little too insubstantial. You can't tell if you're too hot or too cold. Blankets don't seem to work. Come-up can be rough like this. You need to have immense trust in the world that you're ok, that you're not falling apart, that your body can take care of itself and your brain will soon compensate for the new chemical situation and restore homeostasis and understand your modified internal senses.

5. Temporary psychosis. it happens and i am not qualified to suggest a remedy or reasoning to it.

Edit: Sleep! Sleep deprivation is definitely on this list. Can't sleep on acid.

Another one came to mind: low blood sugar. You might forget to eat on acid. You won't feel like eating. It's a good idea to keep citrus around or another source of sugar. It helps a lot!

On 3, I've read about certain American groups that have a history of psychedelic use, holding confessional sessions on their hike to the trip location. This was a chance to clear the air and remove concerns from the users mind that might play on them while in the trip.

Interestingly, due to the low doses many groups take they take these after encouraging a period of fasting and speed deprivation.

Anyway, outside of my area of expertise but something I consider interesting.

To add on to this, I know mixing drugs isn't kosher, but if this is a real worry to someone taking it, having xanax on stand-by is a good idea. SWIM came very close to a bad trip many times, on high doses, and having a "break glass incase of emergency" was enough to get through it.

I'd like to chime in with a personal anecdote relevant to what you've mentioned. The TL;DR is "Having Xanax is incredibly comforting when a trip goes sideways; it worked for me and friends, it worked fast, and it was quite effective."

The day before yesterday, a friend and I took 2CB nasally for the third time, for both of us. Quick note: 2CB is roughly similar to LSD.

As it turned out, the previous two times we had been losing quite a bit of 2CB during the snorting process because we where basically pressing our faces against the surface then inhaling. This led to some 2CB stuck on our face, some stuck just inside the nose, etc. Because such small amounts of 2CB are so effective, this loss meant we where experiencing an order of magnitude fewer effects.

So, it's our third time, but this time we decide to use a straw. Using a straw meant we got the full amount instead of losing the majority. The net effect was we found ourselves in the middle of an experience that was orders of magnitude more than what we where emotionally prepared for. If we'd been aiming for the experience we where having, we'd have been fine; but since it was so unexpected it felt very uncomfortable.

After about an hour, my friend was lucid enough to get a Xanax for himself and offer me one as well. The Xanax stopped that trip in it's tracks. 15 minutes after taking, lucidity solidified and I was back to being able to hold conversations. Within 30 minutes, we where down to only very subtle visuals, and within 45 minutes, the trip was effectively over.

To reiterate, Xanax worked for me, and I'll be keeping it around as a safety feature in the future.

Doesn't snorting 2CB burn like hell?

2CB dilutes in water with a little effort and it's much easier to measure out consistent doses in tablespoons or mL of a liquid rather than very minute amounts of a powder.

Fun drug, but it upsets my stomach.

I've never done psychedelics, although I was a trip sitter a few times back in college.

It was generally nice. We went out to outrageously gorgeous outdoor parks, and I kept people from wandering off cliffs.

One time, somebody was having a terrible trip (which I hear is the equivalent of an actual vacation in hell), and he stopped it with his Clonazepam prescription, which is essentially a longer lasting drug in the same class as Xanax.

This is true.