There are two basic types of pills or weight loss pills – ‘prescription’ and ‘non-prescription’ pills.

Prescription Pills :

They are treated like drugs. They require FDA approval and are closely regulated. examples of this type of weight loss pills are Xenical (Orlistat), Meridia (Sibutramine) and Phentermine/ Fentermine. To prove their effectiveness in weight reduction, these pills are subjected to a range of clinical tests typically for monitoring health risks and side effects.

Non Prescription Pills

are also called as weight loss supplements. They can be purchased over the counter as they are subjected to minimal FDA regulation only. Some examples of this type of weight loss pills include pills from Metabolife™ and Herbalife™ as well as fat-burners, herbal weight loss pills, stackers, other sports or diet supplements.
The difference between prescription and non-prescription weight loss pills is becoming narrower. Since some types of non-prescription pills can be just as powerful or dangerous as weight loss drugs. Exception is that these types of weight loss supplements are not regulated similar to prescription weight loss pills. Hence they can be more dangerous if anything. The FDA has issued warnings recently about weight loss supplements that contain ephedra. Hence, many drug manufacturers are now declaring as ‘ephedra-free’ by removing ephedra from their weight loss pills.