But the thing about the Andalites and food was that it was a new sense. Ax ate things that are disgusting, but flavorful because he'd never had that kind of sensation.
I have no idea what narcotics Andalites have at home, but either way, those effects are physiological, and despite the fact they their anatomy is very different from ours, it's suggested the physiology follows the same rules. Ergo, I don't think they'd be inherently more vulnerable to addiction or the effects while in a human morph because potentially those effects are something the Andalite form understands, unlike taste.
Out of morph,while their may be different sensitivities to certain chemicals, just like there are in humans and other animals to certain drugs, in their own body, suppose they could have an affect, but it could end up being noxious.
