It's probably okay, since the same doctor prescribed both of these for your daughter. While she's young and sometimes there are worse side effects for younger people, sometimes the doctor has to weigh the benefits against the consequences of NOT prescribing and hope that the negatives will be minimal. I'm sure the doctor will be monitoring your daughter closely, at least in the beginning stages of taking the medications. I hope everything works out well with this.
It would be best for you to ask either her doctor or another medical professional. I have read on only a single forum that some people experienced more anxiety on Cymbalta and then took Xanax as an emergency anxiety attack med. I can't take much from that but it was the only thing I found when I googled Cymbalta and Xanax.
http://ehealthforum.com/health/cymbalta-and-xanax-t139410.html
The link if you would like to look.
It's also good to remember everyone's body is different. What may be an apparent miracle worker to one may be a hellish experience for someone else. I'm not a medical professional and I can't offer any first hand experience as I have not taken these drugs. All I can do is offer what little advice I have. As I said before, best to ask her doctor or another medical professional.
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