Michelle,
Just to let you know that claritin is approved for children, I think age
6 and beyond. However, it is used on younger kids. My daughter is on it
right now, she is 3 yo, but only weighs about 22-23 pounds. Very recently
prescribed by my  very experienced and trusted pediatrician.  You can
forward this post to your client for her consideration, to help her make
her decision. She could ask her pediatrician if he/she ever uses claritin
syrup in toddlers. This would be more ammunition for her.  Also, aren't
these meds taken on a short-term symptomatic basis (during peak allergy
times or allergy attacks) and not on a regular, daily basis? Good luck.

The best fed babies are breastfed babies!

Laurie Wheeler, RNC, MN, IBCLC
Violet Louisiana USA