I've taken it a lot over the years, sometimes at fairly high doses and never had an issue. Maybe it is related to phenergan (I think it is); phenergan contains a warning that it can create mania in someone susceptible to it. And boy did it for me...scary, scary hallucinations and I was already so sick (was on it to help me stop vomiting after lithium toxicity)....but hydroxyzine has always been completely safe.