What works against tooth pain from whitening?

Let nature work: I am assuming that you were examined first by your dentist and have no cavities. It should go away on its own shortly after you stop the whitening. If not, see your dentist who can suggest several things such as desensitizers (otc toothpaste and office applied medications) as well as Fluoride rinses\gels. Avoid eating and drinking very cold foods and liquids meanwhile.

Stop whitening: You should stop the process, and use a desensitizing toothpaste. This is one of the unsung problems of whitening teeth......Time will usually help as well.

Stop using it!: Use a less abbrasive toothpaste like sensodyne and see your dentist to be sure you do not have any underlying cause for the sensitivity.... Even if the pain goes away.

Time and percentage: The key to whitening is time the agent is used and the percentage of the chemical agent. You can use a desensitizing toothpaste to help. Using a professionally made tray is the most efficient way. Do not use otc or tv ad stuff. Stay away from dentist using the power bleaching in their office, which have a bad reputation for sensitivity.

Bleach=Sensitive: If you are using trays to bleach with after the bleach is cleaned out between sessions you place a prescription Fluoride gel that can be placed directly in the tray and the tray reinserted which has been found to help the sensitivity. Also, sensodyne can be used in the tray in the same manner, simply bathing the teeth in these desensitizing agents may give significant relief.