What's the advantage of levocetirizine over cetirizine for pediatrics with allergic rhinitis?

None: There is no outcome benefit to levocetirizine (xyzal) over Cetirizine (zyrtec). Levocetirizine is just the left mirror image of the chemical while Cetirizine contains both right & left halves. In theory, for this chemical, the left half is supposed to be the active molecule but in real life, it's doubtful anyone can really tell the difference. More likely than not, levocetirizine is more expensive.

None really: Possibly less sedation, otherwise no advantages.

Both are effective: Levocetrizine is third generation non sedative antihistamine developed from cetirizine which is second generation.It is claimed to be more effective and with fewer side effects than cetirizine.But there are no published studies to support that In my opinion they are both effectice and cetrizine is available over the counter and is cheaper and as effective as levocetrizine There is no advantage

None: There are no published articles that show one has an advantage over the other. You might want to do your own trial. All the best.