But for allergies, I would think a different approach would work better. How about this?: Show a dog-lover who likes gardening look at their flowers, and the flowers morph into scary monsters via CGI, and then their dog turns into a vicious werewolf beast, and the music turns to horror movie music, etc., and then the actor/actress could say that their horrible allergies turned their favorite things (like flowers, pets, etc.) into oppressive, scary things. But now that they use Allegra, it has broken the spell and turned the threatening things back into beautiful flowers and loving, cute animals, etc. I think this would work far better for an allergy medication. (Has this idea been done before? I don't believe I have seen it.)
I'm sorry, but I can't find this commercial anywhere except for on the Allegra website on the ads page (It's called: "Architect" if you'd care to seek it out.), but this page has a glitch on it where it tries to play the audio for all the clips at once, and it's very annoying, so I'm not including a link here. But it's just b&w shots turning into color, etc., so you can imagine what it looks like pretty easily. (It basically looks like an ad for an antidepressant.)