You actually have to be 18 or older to buy most supplements under some company policies or labels because, as you may know, most supplements are approved by the FDA, so you take them at your own risk. The American Academy of Pediatrics (AAP) recommends that people under 18 years of age should not use body shaping supplements. However, it's still legal for minors to buy these products in 49 states, even though they're labeled for adult use only. There are no legal age restrictions on buying medicines.
The sports supplement market is booming and its goal is to advertise to young athletes that they can safely improve their exercise and sports performance with their products. However, most supplements for children under 18 are not regulated and may contain harmful ingredients.