I have been on zyrtec for about 2 yrs. I gained 70 lbs. I'm never full. I eat everything in sight. Everytime I try to go off the zyrtec, I break out in hives, that never happened to me until I started taking it. I'm now trying to weane off. I went from 10mgs. to 5mgs. Now I don't know where to go from here, thats the lowest dose for an adult.