She's right, don't mix herbs and your meds. My former pdoc and my present say one shouldn't, risk of reaction and interactions. Herbs and their properties are not documented and regulated like medications manufactured by pharmaceutical companies, where medications have to go through clinical trials,everything being documented,etc. before FDA approval. Herbs,purchased at many health food stores haven't been put through this process, so one has much less an idea of how many different reactions/interactions will occur with their prescribed meds. In doubt, I'd clear this with the prescribing doc,before mixing anything, even if someone says it's safe to. It's better to be safe than sorry.
Take care,
Roe