I am taking the over the counter weight loss drug Alli, how long can I take it for?

If you have no adverse effects, then you can take the drug for 18-24 months. However, if you have not lost any weight in 3-6 months, it is unlikely the pill will work in future. From clinical studies, the drug seems to work adequately for about 12 months. You can expect a weight loss of about 1-2 pounds a months as long as you combine it with changes in diet and exercise.