What causes my teeth to hurt when i rinse my mouth with crest whitening mouth wash?

Temporary sensitivit: Most bleaching agents will remove oxygen in the tooth, this is not hurting the tooth only your sensitivity which will only be temporary. Just try to rinse with tepid water to keep the sensitivity down. Or use a sensitivity tooth paste every other time which may diminish the sensitivity. Bottom line is you are not hurting your teeth and the rinse is working, .

Peroxide: Enamel and dentin are porous. When bleaching agents com in contact w/ the teeth they can cause sensitivity, especially to cold.