Is CTB possible without antiemetics? Yes.
There are cases of people who took only pure SN and died.
Even a few grams of SN can be fatal.
The key to CTB is pure SN, fasting, no people around and not calling for help.
However, antiemetics are highly recommended.
Antiemetics are helpful and increase the chance of success. Unfortunately, it is hard for me to say how much.
They can also make the whole CTB a bit more enjoyable.
But it is important to remember that even antiemetics do not guarantee no vomiting.
You definitely have to mentally prepare yourself for vomiting regardless of whether you take antiemetics or not.
So, to sum up, CTB without antiemetics is possible, but the chance of success decreases, but as I mentioned above, I do not know how much.
The more SN is absorbed by the body, the better. Vomiting interferes with this and makes the whole process more difficult.
Benzo is not mandatory.
But Benzo can make the whole CTB more enjoyable.
It also increases the chance of success, because for example, with Benzo you can panic less and you won't call for help.
In general, it's a very individual matter.
If you are afraid of panic and want your CTB to be more enjoyable, Benzo can be useful.
The final decision is always completely up to you.
Here is a thread that answers the basic questions:
https://sanctioned-suicide.net/thre...-method-comprehensive-guide-sn-method.121672/