Hydroxyzine can have the oh so cheerful side effect of repressing breathing to various degrees. It’s a rare side effect UNLESS you already have pulmonary issues, then it becomes really common according to my pulmonologist. It shuts my breath response off entirely, so I can’t take it at all unless I’m intubated, but for people that it merely represses breathing / lowering o2 sats? A common side effect to that is increased anxiety. Depends on how low your o2 saturation goes. If you have supplemental o2? Try jacking the setting up a couple liters to account for increased anxiety from a lower pulse ox. Because taking something that lowers your overall anxiety isn’t going to help much, if anxiety A is simply being replaced by anxiety B.
As always, not a doc, check with your own doc before doin things like messing with your o2 tanks unless you have their go ahead to adjust liters as needed, etc.