Yes, Hydroxyzine is the most potent of the " Classical" antihistamines,, and also sports some mild anti-anxiety (anxzyiolytic) effects
However, low doses should not be RX only because it is just so safe; unlike diphenhydramine, and even promethazine (Phenergan), Hydroxyzine has no anticholinergic effects, so it would take over a gram to experience side effects
Granted, IV administration is dangerous, yet the Pamaote, (Common name Vistiril) is not water soluble
Note that both Hydroxyzine and promethazine are otc in other countries and they should be
BTW, Hydroxyzine KI ~1, diphenhydramine closer to 20, cannot remember promethazine
Desloradine is 0.4, though it d I es not freely penetrate the BBB / Central nervous system
Hope this helps