allergies
"I took this three days ago and was up all night. I didn't make the connection as I had a cup of coffee later in the evening than I normally would. I took another Xyzal the following day. I still have not slept. I have been up for 3 nights!!! I have a heavy duty sleeping pill that I am going to take tonight and I'm hoping that will be the end of it. I can't imagine it would take longer than 72 hours to make its way out of my system. If you are someone who experiences these types symptoms with certain medications, avoid Xyzal."