It's enhance with an 'e' FYI, and hydroxyzine, although it's my favorite antihistamine although diphenhydramine is just as good and sometimes more effective for antihistamine effects, but for combination with opioids, I prefer hydroxyzine at the right dose.
Hydroxyzine is a pretty cool drug, it's an anxiolytic, antiobsessive, even mild antipsychotic action but nothing serious, also analgesic, sedative, hypnotic and tranquilizing properties. On paper, it seems to be quite the wonder drug. In reality, It's good for antihistamine needs in general, although for stronger itchies like morphine I'd definitely go with diphenhydramine. Hydroxyzine is great in combination with benzodiazepines.
I take 50-100mg hydroxyzine before I dose my opioid analgesics for the extra antinociceptive properties.