Gotta be careful with guarana... it's hyper-loaded with (naturally-occurring) caffeine, so don't mix it with alcohol or drink it before engaging in physical activity. Doing so could result in severe dehydration.
There have been stories of high school kids in North America drinking several guarana-spiked "energy" drinks before football or hockey games and then having heart attacks on the field.
There have been stories of high school kids in North America drinking several guarana-spiked "energy" drinks before football or hockey games and then having heart attacks on the field.