This has been my favorite thermogenic thus far!!!! I use it as a daily supplement rather than a boost before working out and have had no adverse side effects. It gives me a great boost of energy in the morning ans helps me get my day started. I have a very physical job and I am constantly moving so this does not give me the jitters. I do not take this on the weekends because if I am just sitting I do start to get a headache. This paired with clean eating and regular (daily) exercise has done wonders for me!!