xeneadrine makes a non ephedrine(spell check) version now which is much better for those who have a history of heart disease or are concerned about heartrate increase. Notallthere is correct regarding the fact that you're body will build a tolerance and then the shits useless...ya won't even get the pick me up. Like all things though use it in moderation and follow the directions to the letter. Doctor Qwest has spoken. PS. I love drinkin on xeneadrine, not supposed to but....