Get the facts

I have often said that medication that is not prescribed by a health-care professional is a risk. I am not saying that you should not take anything that you see advertised, but I am saying that you need to be sure that you chek a few things out first:
Trustworthy retailer - first of all, you should check that the retailer that you have chosen is reputable, is properly qualified to sell and is registered/licensed to sell products of this nature. Also run a check on the company yourself, look for online reviews and make sure that the contact details are correct - if they are not 'up front' about their street address and phone number, I would say that you should not do business with them.
Trustworthy product - you should also check out reviews for the product such as alli reviews, when doing this, I would advise you to seek out independent reviews. It also pays to find out exactly what the side-effects will be, a reputable retailer will make this information freely available. Any retailer that claims no side effects, probably means that the medication is ineffective at the job it is supposed to do..