We haven't, but I think a few times when she got bad and we took her in, our vet gave her an antibiotic shot.
I know that in Humans anyway, histamine blockers have almost no side-effects compared to antihistamines, so I'd think for prolonged use over several weeks that would be better, at least if it worked that way in cats. I suspect it's just that they're newer and so haven't been tried much. We asked our vet a few years ago but it seemed he just wasn't familiar with blockers.
Ah well - seems to be pretty much the stock answer but thanks - I'll accept.
Well I think it's a matter of your definitions.
The consumer website for Claritin is written very much in layman's terms.
Some people use the term "antihistamine" to mean both the traditional type and the newer blockers. The technical papers all describe Loratadine as a blocker.
Oh well - the main thing I was looking for was confirmation that cats didn't have some feline-specific reaction to loratadine, which it sounds like they don't.
I might try it based on body weight ratio to the human dose (like <1mg for a 10 LB cat) when we take her collar off this season.