The teeth whitening is done using chemicals like Hydrogen and carbamide peroxide, and they are pretty harmful to the other tissues in the mouth, including the tongue and gums.

These chemicals can cause the bleeding and irritation of the soft tissues like gums, cheek and the tongue. The negative effect of the whitening agents is not limited to just the mouth, but also can cause abdominal discomfort and diarrhea.

The dosage when taken in mild amounts still is pretty safe, but when taken in higher concentration, can cause respiratory problems too. Excessive usage of the teeth whitening techniques can even rub off the top layer of the tooth.

The above is a reason why it's always advised to visit a dentist before trying out any teeth whitening products. The dentists can assess whether the person can use any teeth whitening procedures at home, or has to get the proper guided and trained care for the whitening.

It isn't compulsory that every teeth whitening product would be causing the bad consequences, but it is not uncommon.

Dr. Chetan