Dr. Gupta: Things to know before taking alli

By Dr. Sanjay Gupta
CNN Chief Medical Correspondent

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(CNN) -- A fat-blocking weight-loss pill called alli is the first diet drug to be approved by the FDA for over-the-counter sales. It's a reduced-strength version of the prescription medication Xenical. Here's what I think you should keep in mind before considering this drug:

1) Diet and exercise are still going to be your longest-lasting weight-loss solution.

2) The manufacturers of alli and the FDA emphasize that this medication cannot work alone. It must be combined with low-fat diet and multivitamin taken at bedtime.

3) There are side effects, and they are not pleasant. Since the medication works by blocking fat from being absorbed in your intestines, patients may experience diarrhea, bloating and cramping.

4) Eating a low-fat diet, while on this medication will reduce side effects. And, of course, eating a high-fat diet will increase the unpleasant gastrointestinal side effects.

5) This is not a miracle drug. You will still have to work for the weight loss.

6) While the prescription version, Xenical, is approved for anyone 12 and older, the over-the-counter version is intended only for adults 18 and older.

7) If adolescents are taking the medication, they should continue to do so only under a doctor's supervision.

8) If you have had an organ transplant, you should not take this medication because of possible drug interactions with cyclosporine, an anti-rejection medication.

9) If you are diabetic, have a thyroid condition or are on blood thinners, talk to your doctor before starting this medication.

10) And the big question: How much will you lose? Expect modest weight loss. If you lose 5 pounds through diet and exercise, the FDA says you can expect to lose 2 to 3 more pounds by taking this pill. By the way, the weight loss plateaus after six months.