If you are taking carnitine, be careful with how much you take. Taking too much can cause serious side effects like heart palpitations, not sleeping at night, and nausea. I took the recommended daily dosage of 4 capsules, but after a while I started to experience these symptoms. When I stopped taking the supplement, the symptoms went away. Now I take 1 capsule every 2 days and I don't have any serious issues, but I still don't sleep well sometimes. My advice is to not take more than the recommended dosage and don't take extra caffeine, as it can put extra strain on your heart.