Check for FDA Approval. The FDA has very stringent guidelines and gives its approval only after a product has passed a series of rounds of testing. Thus, ask your doctor or your pharmacist if the diet pills you are being given are FDA approved or not.
Check the ingredients. There are certain diet pills that act more as diet supplements rather than diet pills. The safety of such diet pills is slightly higher when compared to conventional diet pills. This is because some diet pills contain ingredients that only help to clean up the digestive system, thus, only causing mild weight loss by removing the accumulated plaque in the digestive tract. These include pills that aid in intestinal cleansing, like probiotic supplements.