Re: shisha and allergies
I don't think he's worried about actual allergies but an allergic reaction.
My cousin is allergic to oranges so I steer clear of anything that might have oranges in it (fruit mixes, orange, etc) to make sure her throat wont close up and you know, and the possibility of death doesn't ensue.
So, i wouldn't risk it.
GLaDOS: "You euthanised your faithful companion cube more quickly than any test subject on record. Congratulations!"