Herbal Diet Supplements

A few months ago when I was not yet pregnant I was tempted to take a herbal diet supplements. My friend takes this and she told me that it really works. She indeed lost weight after a few days. But I was so afraid to take some as I heard it has side effects. What if won't be able to conceive again? What if it won't take effect on me? What if I get sick just by taking it? A lot of 'what if's' run through my mind. I waited and get myself to be ready in taking it until I got pregnant. Will just try it after giving birth. For sure I won't have the what if's as fats will surely be all over me and I need to take it all off. =)