Taking Vistaril (hydroxyzine) 25 mg @ night for month. Suppose to help with sleep & anxiety but one of my doctors said it only has a shelf life of 4 hrs???

Half-life? I wonder if your doctor was referring to Vistaril (hydroxyzine)'s "half-life"? That's the time it takes the body to reduce it to half it's "potency, " and 3-4 hours is about right for Vistaril (hydroxyzine). The advantage of Vistaril (hydroxyzine) is that it acts within about 30 min, is not a high risk for dependency, and is especially good in helping people get to sleep. If staying asleep becomes an issue, other medicines may help.