All products mentioned are over a year old, have been used daily by many people, and work. But there are a lot of products out there that say it will "lighten" but are still not doing it. I believe that you can make a big difference by simply buying products with a claim that they lighten teeth. Here is the link to my complete list of products. I also have a list of the most important teeth lightening products.
Bismuth Oxychloride: This is the only brightening product I am recommending. It is the lightest whitening product. It also contains some of the most active ingredients for lightening teeth. It can also be used as a mouth wash. Bismuth Oxychloride is not an approved by the FDA, but it has been around for decades. Bismuth Oxychloride can be used by mouth and needs a prescription. It is sold in a wide variety of strengths, including 0.5 to 2 grams. You may choose to use Bismuth Oxychloride alone or as a whitening solution.
Bismuth Oxychloride is an extract from bismuth. It is a natural substance, which means it is not only safe but can be used in very small quantities to treat some conditions. It works by improving the blood flow to the teeth and preventing cavities.