In suffering pretty bad from allergies right now. should i switch from claritin (loratadine) to zyrtec tomorrow?

Yes : Yes, you should! Zyrtec in my clinical experience works better, the trade off is that it's a little more sedating than Claritin. If sleepiness is a problem, then take the Zyrtec at night before bed. Hope this helps! You may need a nasal spray if this doesn't do the trick. Hope this helps!

Need more : you might consider some of the nasal inhalants that might help. It would be best for your physician to prescribe these, or if necessary have you seen allergist they can better clarify your best therapeutic approach