My friends pediatrician said it is too strong for kids. I forget exactly what else he said. It was a few years ago but I do remember her telling me her doctor said kids sholudn't use a a/p.
EDIt - found this in an article
A concentration of toxins leads to cell mutations: a.k.a. CANCER. Yes, ANTI-PERSPIRANT. Most of the products out there are an anti-perspirant/deodorant combination, so go home and check. Deodorant is fine, anti-perspirant is not. Here's why: The human body has a few areas that it uses to purge toxins; behind the knees, behind the ears, groin area, and armpits. The toxins are purged in the form of perspiration. Anti-perspirant, as the name clearly indicates, prevents you from perspiring, thereby inhibiting the body from purging toxins from below the armpits. These toxins do not just magically disappear. Instead, the body deposits them in the lymph nodes below the arms since it and cannot sweat them out.