Whitening Pre-Brush Rinses

I'd like some input from anyone who has used Whitening Pre-Brush rinses.
Do you feel it's working to whiten your teeth? Have you had any after effects from using it? What brand do you use?

I bought our grocery store's 'generic' brand that says it compares to the ingredients of Listerine®. I've been using it for a couple months now. I do feel like my teeth have whitened a shade or two, but not more than that. However, what has been happening this past week is after swishing for 60 seconds and spitting out, a few hours later I get this 'nasty' mucous like secretion in my mouth. It turns my stomach and I gag even while expelling it. All I can think it might be is thin layers of skin being shed my the roof of my mouth or the inside of my cheeks.
I only notice this a few hours after I've used the rinse. Stop using the rinse you might say, lol. Yes, that would be the sensible thing to do. I still want to know if it's the hydrogen peroxide in the solution causing this or something else.
So, if you've used products like this and have had good/bad reactions, please post them here!