I've tried probably every energy drink on the market, every energy bar. Some work better than others, others simply don't work., the effectiveness of any supplement does involve a person's individual chemistry. I have taken "Up Your Gas" now for several months. They do exactly what they say they do... without the jitters, no grumpy down swing as you get with caffeine related products, really no side effects whatsoever! I only take half a tablet... they are that strong. 10 minutes later, zoom... for about 3 hours or more. Good stuff!