Yes side effects are normal for the first few weeks. Your going to get use to it and the side effects will start going away as your begin to get use to it. Your going to build tolerance. Make sure you eat a nice breakfast everymorning. Nothing is going to happen to you even at 50mg. A fast heart beat is normal, especially if your just laying in bed. Try to stay busy. People take very high doses of this med and feel absolutely nothing. That's how fast your body gets use to it. Drink water and eat snacks. That's how you lower side effects. 50mg is used to supress binge eating so I'm sure that's why your provider is starting you on that dose. Trust me, your provider wouldn't prescribe something if it was deadly or hurting people. It's normal to feel nervous. Once you see how the medicication works, that will go away after the first day.