I completely understand why schools have this rule, and other rules. Its a societal problem. A tylenol bottle can be used to conceal some other drug. I hate that our society has dropped to such lows that it results in honest kids having to carry the consequence. Some kids do drugs, so no kids can carry their own tylenol, ibuprofen, eye drops or even hand lotion. Some kids shoot up schools, so no kids can return to their car after enter the school. Some kids search for porn on their phones, or use the phone to cyberbully, so no kids can use their phones during the school day (even though I have had teachers tell me to have my child us his phone to track assignments...mixed messages). Some kids bring alcohol to school in their water bottles, so all kids may use only clear bottles. Lockers and backpacks carry their own issues too. Heck, even simply using the bathroom is not a normal process for kids in school, they need "permission" to relieve themselves.
My point is, perhaps the child has tylenol for another purpose, it is also a pain reliever. Bottom line, the kid was breaking the rules to have it and it's a shame that this rule has to even exist. You can't trust people to make logical and rational decisions. Too many are skirting the rules. Meanwhile, the administration/teachers also skirt the rules. Mixed messages, and policies not being adhered to.