Do you know what it is in Alli that causes the side effects? Do you know how the drug works and why it sometimes results in the side effects?

alli combines with the fat you eat, and turns it into a form your body can't absorb. It is then excreted, and since it is a lot of fat, you get the oily stool and other problems.

It sounds rather simple, and it doesn't sound too bad. Does anthing else contribute to the side effects?

I don't know what it does that means you shouldn't take it if you have kidney stones, for instance, or have had heart trouble.