Stacker 2 is an energy‑focused dietary supplement brand developed by NVE Pharmaceuticals in 1997. Originally containing ephedra, it’s now ephedra‑free, featuring caffeine, herbal extracts (green tea, yerba mate, kola nut, white willow) to boost metabolism, energy, and suppress appetite. Stacker 2 gained popularity in the early 2000s through endorsements by WWE wrestlers and NASCAR drivers. Although reformulated, users still report stimulant-related side effects such as jitteriness, insomnia, elevated heart rate, nausea, and increased blood pressure