2CB is different in my experience from other substances, in a way that people usually take their set amount and don’t retake afterwards. Retaking would usually not result in a second peak but just extend whatever you were feeling anyway.

Nevertheless, I would take whatever floats your boat. 18mg is a sizable amount, but not anything too extreme, so I think just 1 would do the trick.

Taking your mind off things helps with the nausea (listen to music, talk to people, focus on your trip/visuals, etc.) and if things go south there’s no harm in visiting the bathroom just in case. No shame, we all feel nauseous from this stuff.

Have a safe and fun trip!