Does teeth whitening have any side effects ?

Yes for some people: Yes...Some people get sensitivity to cold and or sore gums.

Tooth Whitening: In some instances, tooth whitening can cause increased sensitivity to hot and cold beverages and foods. That can depend on how much of the surface of the tooth and root are exposed, whether you have gum recession, as well as your pain threshold. Follow your dentists recommendation regarding the type of bleach you should use, how much and how often. If you are using bleaching strips, be careful.

Teeth whitening : Teeth whitening can cause tooth sensitivity. This usually lasts only for a short period of time after whitening. I recommend using dentist provided whitening products or products made by major manufacturers (like crest white strips).