User blog comment:MrSolomon/Solomon's Tale 5; Legacy of Destruction/@comment-2037710-20150804213314/@comment-2037710-20150806062904

Alice immediately noticed Bess's magic mercury shortly before it took effect and even knew it was poisonous miasma before Bess announced her treachery. She also immediately realized Queen Alraune's poison when she declared she was going to refine it while explaining its effects to Luka and recognized some of the hazardous drugs lying around in Lily's Mansion from brief glances after Lucia is repelled.

It's quite clear she's well-versed in toxins. So, attempting to poison her would have a very high failure rate (even in her sealed body Bess' mercury had no effect on her, and she actually drank the contaminated water to the point where Luka noticed a drop in water level) unless, as Alex said, she's extremely hungry.