"You look pretty sick to me."

He flinches a little when she huffs and then feels like a real heel for flinching. That does set up a series of sudden associations in his brain, at least.

"...Or, uh, poisoned...? If it gets in your blood, you can go down just like that, take it from a guy who's been poisoned a lot."

He's exaggerating his experience, but she doesn't have to know that, confidence is important!