Where did you 'find' said tablets? There IS a max dose per day and a set amount you should take that you should not go over. Using the proper dosing is essential. Not taking too much is essential either at once or over the coarse of the day. Is this prescribed to you? What happens to medication when it expires typically is NOT increased side effects but rather decreased efficacy (doesn't work as well). The adult dosage at one time is: Adults—50 to 100 milligrams (mg) 4 times a day. https://www.mayoclinic.org/drugs-supplements/hydroxyzine-oral-route/proper-use/drg-20311434?p=1 Please note that hydroxyzine has a potentiating effect meaning that it can combine with other things you are taking and interact for increased effect (and perhaps not in a good way). Are you on any other medication?
Definitely do not take anymore until you have the clearance from your doctor. And if you feel you took too much, I'd check in with poison control which can talk you through that. BE SAFE. And we can talk about anxiety and insomnia here for coping strategies. Maybe that would be helpful to you.
If you think you took too much and it is affecting you, you need to see a doctor. While the dosing for medications might be found in a general way, doctors dose individuals differently for different problems. For example, this drug has a side effect of being very sedating, which makes it hard for many to take for its intended purpose, but docs have used that side effect to use it for sleep, in which case they might just have somebody take it at bedtime. Some are very sensitive to meds and need less and some need more and most of the time a particular drug doesn't work for a particular individual at all. That's why there are so many of them for similar problems. The expiration date doesn't really mean much unless it's really old. Yours isn't all that old and so is probably still potent. But old drugs would only cause bad effects they wouldn't in normal use if there's an additive that spoils. What you're reporting is over-sedation because you took a lot and because you might be overly sensitive to this med. It is the most common side effect of taking it. So again, if this is going on for awhile you do need to see a doctor but not because of the expiration date but because you may have taken more than you can handle dose wise.