Right away my teeth felt smooth after using it. After a couple of days, I've noticed them growing whiter, especially between the lower front teeth along the gum lines where I thought coffee stains accumulated. The whitening looks like white filling up the tooth on the inside of it. Totally different from peroxide whitening. Pain from cold drinks or foods is going away. The foaming action is pretty strong. It isn't easy to brush for a whole minute without an explosion of foam from the mouth, though it is recommended to keep it in contact with the teeth and keep brushing that long. The taste is delicious.