Jacked is the best pre-workout I've tried. I feel it gives you the "cleanest" feeling of energy. Some other like N.O Xplode made me feel jittery, and kinda weak after a hour. Just remember to start your dose low, cause if you do 2 the first time, chances are your gonna get to jacked lol. Unless your a really big guy. As far as safe, compared to other pre-workouts this has minimal ingredients. If you want to to stay effective, you gotta cycle it, take long breaks off, cause like anything your body gets a tolerance to them.