I am usually fanatical about reading directions, but I didn't on the Bonine; I have no idea why! However, given that background: last year when ds had just turned 5, I gave him 1/2 a Bonine tab on the boat from Catalina Island back to San Pedro. He was already feeling a little queasy when I gave it to him (even though we'd been up in fresh air, looking at the horizon, etc.). He started to feel better and perked up, then napped on me for a while (it had been a long busy weekend, and I don't know if that was the meds or exhaustion), and showed no ill or odd effects from the Bonine.
This is in no way to be taken as a recommendation that anyone else try it...just my experience when I goofed and gave it to him!