Apparently hydrogen peroxide is a popular ingredient for new products these days, because that's the main active ingredient of Crest Whitestrips.
An active ingredient, by the way, is the actual ingredient that makes the product work. Everything else there is what supports its function. Maybe it makes it more effective, like water in a 70% isopropyl alcohol (rubbing or cleaning alcohol for your first aid kits). Maybe it makes it longer lasting, like a preservative in...well, what doesn't have preservatives these days? Even your lens solutions have preservatives.
Anyway, hydrogen peroxide not only sterilizes, but it whitens as well. In fact, you should keep your bottles of hydrogen peroxide away from clothes, because they're strong enough to bleach the skin on your hands!
Effectiveness: It definitely works. But it's not a big miracle. The improvement is slow, and you'll need more than a single package to really be satisfied.
I got the seven day kit, containing 14 pairs of strips (one for your upper teeth and another for your lower teeth), which the package facetiously says "28 total strips." Speaking of facetious, the packaging also says "WHITENS 2X BETTER PER STRIP vs leading dissolving strip." Notice how they didn't say "vs
leading brand"? The leading strip according to Crest is another Crest product, called "Crest Whitestrips CLASSIC," and the packaging also says "Whitens 2X Faster than Crest Whitestrips Classic." Ugh.
Seriously, look at the packaging. "vs. leading dissolving strip" Click on the picture to see it more clearly.You'll also have to confront the grossness of this product. After you apply the strip onto your teeth, they'll easily loose their place, and saliva will build up around them. It's really gross to swallow your saliva, because it tastes nasty and, well, they're all mixed up with the matrix goop that holds the hydrogen peroxide (naturally a liquid, not a solid) in place. During the half hour per strip you'll need to readjust the strips and keep them in their proper place probably at least ten times. Personally, while using the product, I laid on my bed and read a book or stuck a laptop on my belly, so the saliva would just drip to the back of my throat without mixing with the matrix goop. Otherwise, I'd have to be walking tot he bathroom sink every two minutes to spit out my saliva.
Also, Crest has similar whitestrip products. There's the Classic (previously mentioned), the "Pro Effects" (which is supposed to be "Crest's highest level of whitening at retail), and presumably others in production. Apparently they have different levels of effectiveness, which to me, is a deceiving marketing ploy. Naturally, people who buy the most expensive products will rave about "Crest Whitestrips," while naturally failing to make the distinction between Premium, Pro Effects, and Classic. Friends will go out and buy the cheapest version, expecting the amazing results of the most expensive products. This way, Crest can saturate the market with products that everyone can buy (to different degrees of effectiveness), and still claim to deliver a high quality product.
The back of the package also claims "WHITER TEETH FOR 12 MONTHS." It's been 12 months, and I can say whatever whiteness I gained faded away with two to three months.
Anyway, if you're really intent on whitening your teeth without the aid of a dental professional, I'd go straight to Pro Effects. As I said, Crest Whitestrips Premium is already an effective brand, and Crest does claim that Pro Effects is stronger. That said, I haven't actually tried out the Pro Effects; I'm just taking Crest's word here that it's better.