I don't see anything that would concern me if I was taking the 2 together but the half life is so short on it that if you are off of it for a day or 2 it will be completely out of your system.
It doesn't seem particularly dangerous to take with mdma but I'd stop it a few days before a roll just to be sure
Are you taking zyrtec for hayfever or asthma or some other allergic condition?
I use zyrtec for hayfever, but as mdma has a drying effect on the nasal passages anyway, I've never thought it necessary to try the combination.