Can an adult take childrens cough syrup?

It's okay to give half an adult dose. Here's why its ok to give a half dose (it's a little complicated so pay attention, ok?)

So here is the breakdown:

~ for every reccommended (5 mL, milliliter) dose of Robitussin DM ADULT there are 10mg Dextromethorphan and 100mg of Guaifenesen (the only drug in straight Robitussin)

~ The manufacturer has a formulation of Children's Robitussin that has 7.5mg Dextromethorphan and 50mg Guaifenesen per dose. This formula is safe for kids over 4 years.

~ so, if you cut the adult dose in HALF (2.5ml), you will have a dose with 5mg Dextromethorphan and 50mg Guaifenesen, which is similar to the Children's dose (with the Dex. being a little less).

THEREFORE, because the half dose is comparable (if not less) to the children's dose that was made by the manufacturer because of its med content, it is indeed OK to give a child the half dose!