It depends on your goals and where the hyperhidrosis occurs.
The most common areas of PRIMARY hyperhidrosis occur in the palms, underarms and feet. Typically, it is palmoplantar (palms and feet) or underarms, palms and feet.
In my opinion, Botox is best for underarm hyperhidrosis and in special cases for the palms and feet. It has been shown to be safe when applied in pediatric patients by experienced practitioners who have done so. Note, the FDA warning very recently for Botox in general.
I would reserve Botox to the underarms area as the number of injections (needle sticks) is few. It works effectively.
I provide comprehensive hyperhidrosis care as a board certified thoracic sureon and I believe that you should have your son evaluated by someone who provides ALL (and I reiterate), ALL tratment options for hyperhidrosis, not one or the other.
1) ability to diagnose and treat hyperhidrosis properly with anticholinergic medication;
2) to identify those patients that are candidates for iontophoresis and get the insurance to pay for the machine;
3) try topical agents for underarm hyperhidrosis;
4) find optimal candidates for Botox injection and treat them appropriately with all options that reduce injection related discomfort;
5) have experience in properly doing suction curettage for underarm hyperhidrosis, and;
6) perform effective sympathectomy.
In Israel, studies have shown that the younger the sympatehctomy procedure done, the less likely the incidence of compensatory sweating. The youngest patient I have operated on was 8 years old.