At-home teeth whitening can be effective, as long as you have reasonable expectations for your results. Going to the dentist for an expensive teeth whitening treatment will definitely produce a more striking result, so as with most things, you get what you pay for.
At the dentist, you can whiten your teeth by six to eight shades. Whitening toothpaste can get your teeth about one shade lighter and gels and strips can boost the gleam by two to four shades. The one thing about all teeth whitening, both at home and at the dentist, is that it's temporary. How long it lasts varies according to how easily your teeth stain, as well as your diet. If you smoke or consume a lot of food and drink that stain your teeth more easily, like red wine, then the results won't last as long. If you avoid those foods and beverages and stay away from cigarettes, then you may get away with only one whitening treatment per year.