I’ve always used Loratadine or Cetirizine. My AME also said Fexofenadine is fine (if it’s really bad) but in the U.K, you can only get it on prescription so I haven’t used it. The list of approved medicines is reviewed regularly and will also depend who your regulator is. Don’t ask on Pprune, ASK your AME and make sure you declare it on your medical each renewal.
Weirdly this year I’ve had no symptoms whatsoever. Either the grass pollen season is late or I’m magically cured! I’m just off to have my annual class 1 renewal and usually I’m a bit of a sniffling mess at this time of year.