It could be, but if she is forced "vomiting" (bulimic?) then taking Lithium and doing so can become toxic, but that can also depend on what dosage she is on. Is this person a friend or relative that you are close with?? I know it is none of my business but if there are some things about her behaviour you'd wish to share with us we may be able to share some of our experiences with some of the other meds. we have been on or are on now that may be of some benefit to that person.