system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why is 12 the magical age for drug store medicine?

Every time you read the back of a medicine box the age is always 12 when you are considered an adult. Why is this?
gpt
Children have underdeveloped immune systems, at around 11 years old the metabolism of the body begins to change in preparation for/as part of puberty. So children 12 and older have a better way to regulate body temperatures, develop specific immunities, and process toxins, all of which make it so that they are closer to adults and can take medicine differently.