This certainly is true for most tooth whitening systems because they contain heavy metals which attract water out of the tooth, thereby causing dehydration and because the active whitening agent, hydrogen peroxide has an acidic PH. However the Natural+ tooth whitening system that we use is unique. It has no heavy metals, so does not cause dehydration and the hydrogen peroxide has a netural PH, both of which which result in NO or at most very little sensitivity. It also contains natural materials, mostly extracted from the dead sea.