I took Allegra this morning before going to a doctors appointment. I went in for a rash, and they prescribed me Zyrtec and hydroxyzine and suggested I take them before bed as they can make me drowsy. I want to take them tonight, but I'm afraid of they may interact with the Allegra I took earlier today. But I also don't want to wait until tomorrow night to take them because my rash is so bad and so are my allergies. It's been about 11 hours since I took the Allegra. Am I safe to take 10mg of Zyrtec and 25mg of hydroxyzine? Thanks for any help.