I’ve been on Xyzal for my hives problem, Is it safe to have filler injections then?

Xyzal is an antihistamine and should have no interaction with filler injections, so it would be fine for you to have the filler whenever you want.  

As long as you are not hypersensitive to any of the ingredients in the filler being used, it is safe to proceed with the filler treatment. Hives and using Xyzal are not a contraindication to filler treatment.

Taking Xyzal for hives is not a contraindication to using a cosmetic filler injection assuming you are not allergic to anything in the product being used. You can always obtain a list of ingredients from the manufacturer or provider if needed. Good luck!