您是對的， FDA 有告誡：如下

The current recommendations from the FDA are:

Do not use cold and cough medicines in children under the age of 4 unless your doctor tells you to.
Never give adult medicines to children. Only use medicines designed for children.
Never use a cold or cough drug if your child takes other prescription or over-the-counter medicines unless you’ve checked with the doctor first.
Carefully follow the instructions for dosing on the box.
Use the enclosed measuring spoon, dropper, or dosing cup.
Take your child to the doctor if symptoms worsen or don’t improve within a few days.