My friend tried something prescribed by her doctor to help lose weight. I believe they were called 'Apple Cider Vinegar Pills'. She claims that they were working, but then she got violently ill and started vomiting none stop. I blamed the pills (because you shouldn't be taking that much vinegar in) but she says otherwise. In a sense, they do make you lost weight because you'll be throwing up for a week, but it's unhealthy. :[
Basically, weight loss teas and slimming supplements are just a waste of money. A lot of them mess with your system, so you're better off just packing more fruits, veggies and nuts into your diet.