are you taking allegra or allegra d. If it's the d that is a decongestant and could be causing your problems. I took allegra and it didn't do anything for me after 2 weeks so i stopped, i didn't feel or experience anything. I'm taking rhinocort nasal spray now for my hay fever and it really seems to be helping, way more than the allegra did. Plus, it just goes in your nose so there's virtually no side effects.