I've been addicted to Zyrtec since it was first available, only by prescription… that, coupled with Flonase makes life livable.
Only problem with Zyrtec is trying to get off it. A lot of people experience severe skin itching for an extended period when stopping. They don't mention that in the side effects, but apparently it's not that uncommon. Last time I stopped it (after winter hit) it took about four months to quit itching. But, when allergy season rolled back around, nothing else worked, and although I'd sworn to never take it again once I got over the itching, I knuckled under because nothing else worked and I was miserable. It's the devil!