The white strips come in the form of transparent strips. Brush your teeth before putting them on, and moisten them directly before you apply the strips to make sure they adhere easily. Also, be sure your hands are completely dry before applying. (I’ve made this mistake before, don’t be like me.) Once you put them on, they’ll stay put as they work their magic and begin dissolving.
They dissolve in your mouth after about 15 minutes, and you don’t have to worry about anything else—they’re made of edible, water-soluble polymers (pectin is one of the ingredients), so no need to worry about accidentally swallowing as you would for normal whitening strips. For best results, try to avoid rinsing, drinking, or eating directly after they’re done dissolving, but there’s no hard-and-fast rule against doing so. You can use them every day for a week of complete treatment or pop them on whenever you feel your teeth need a touch-up.