I've been taking generic Zyrtec for around 4 weeks for seasonal allergies.

Is it possible for it to quit working already?

My eyes have been intermittently watering for about a week. Now today, I'm sneezing my head off!

The ragweed is very very bad right now.

I'm not supposed to take more than 1 pill every 24 hours, but I feel like I didn't even take one last night. (I did, I really did!)