Seasonal Allergies

I'm almost 5 weeks out.  With Spring in the air, I start to get those pesky allergies.  I crushed a zyrtec and ate it with breakfast.  Now I am barely able to keep my eyes open.  Before they were no problem.  Why is this happening now?

OOPS!  I'm pretty sure it's meant to be an extended release formula!  Not supposed to crush that kind.