allergies
"First time using Xyzal last night for allergies. Normally, I take Benadryl but wanted to give this product a try as it's new OTC. I only took half a pill at bedtime. Yes, my allergic symptoms cleared up but WOW did it make me tired. I'm thankful I have the day off as I don't know how I could function at work.  I expected some drowsiness but this far exceeds the effect of a full dose of Benadryl."