How long does the next day groggy feeling last after taking hydroxyzine before bed?

I myself had taken hydroxyzine before bedtime for at least a month, because I had trouble sleeping due to high anxiety. I took 50 mg before bed and within 45 mins, I was asleep. But the only downside is that, I felt drowsy during the daytime for weeks. So I had to get off. This is just my experience. Give the medication a shot. Everyone reacts differently. Like Wildcat said; side effects usually resolve within a few days or weeks. But if these side effects go on for a while. Then Let your doctor know.

Tyrese

Hydroxyzine is an antihistamine with sedative effects. If you've just started taking it this side effect may resolve in a matter of days to a week or so as your system adjusts to the drug.
If this has been going on for a while let your health care provider know and get their advice. It may be that a temporary lower dose may be helpful or it may just be a matter of waiting it out.