Hello, Welcome to Just Answer. There is nothing wrong with the answer quality. There is nothing in one cetirizine that isn't in the other except different FDA-approved fillers and dyes. They would not be FDA-approved if they caused such side effects. Both Pack and Perrigo are makers of generic drugs and both have excellent reputations.
If your son's pediatrician believes he is having an allergic reaction to one of the fillersor dyes, then the simple answer is going back to the one that doesn't cause the problem. However, that isn't a likely scenario and the pedicatrician needs to be looking for what is really causing the symptoms he is having. While an allergic reaction isn't likely, you can never account for what one individual out of 25 million might be allergic to.
No problem. Here they are:
Pack Pharmaceuticals inert ingredients for generic cetirizine: hypromellose, lactose, magnesium stearate, maize starch, polyethylene glycol, povidone, titanium dioxide.
Perigo Pharmaceuticals inert ingredients for generic cetirizine: cornstarch, polyethylene glycol, FD&C Blue 1 (CI 42090), hypromellose, lactose (milk), magnesium stearate, polydextrose, polyethylene glycol, povidone, titanium dioxide, triacetin