She's tough in physical damage (and emotionally but not relevant to this). A ton of poisons wouldn't care about her healing factor and durability so would effect her the same as an unenhanced human with some added weaknesses to poisons that are effecive against dragons, should they exist. She would develop a resistance to neurotoxins and other stuff no sooner than a human would, and I don't see many people developing effective resistances any time soon. Just make sure you don't botch it the first time and get a lethal amount in.