I took 10mg of Meridia for 4 weeks and lost 16 lbs. I then changed to 15 mg and lost 1 lb in three weeks. Why did it stop working so suddenly? I have no side effect anymore and I can't understand why it would work great one month and then just stop the next month. The bottle I have at 15mg expires January 2010. Is it possible I got a bad bottle? Very frustrating when you're paying $100 a month for it. It was great the first month, now I'm frustrated.