I think you should at least mention the laxative effect. You don't have to tell her in a way that says she's doing anything wrong (most people hate that). But, without seeming critical, casually mentioning that you've learned that the ingredients are in large part a laxative would be a courtesy (rather than she find out after she's drunk large quantities in a short time and find out herself in a very unpleasant way).
My Etsy shop (currently closed for the summer)
My DH likes to go to the asian market and buy things that look interesting, especially tea. One day he brought home a tea I had never heard of so I looked it up. It was a laxative tea. The box didn't say diet tea or laxative, it just said "whatever" tea. One reason to always look up ingredients of things you are not familiar with and see what effects they may have on you
You can't out-exercise poor eating habits.
I've never understood that reasoning Laxatives may empty your bowels quicker, but do nothing for the extra fat on our bodies. Plus by the time the food has reached that point in your intestines, your body has already processed the calories anyway. When I diet, I want to get rid of the layer of fat under my skin. Sitting on a toilet isn't going to do a darned thing for that.
Hello friends, I am not particularly concerned about the nutritional properties or the taste of any given product when it comes to weight loss. But unlike the mistake which most people make I do like to investigate about a product before trying it in person. Now regarding the use of diet teas I have come across people who are rather optimistic about their weight loss properties and some people I have even met in person who have used the same as a mean for their weight loss. Now some people I see are saying otherwise, so I would like to know how did the diet teas prove effective to some while the otherwise to another section?