Over-the-counter tooth whitening products you can purchase include toothpaste and products with bleaching agents, such as whitening strips, gels, rinses, pens, and gel trays.
Typically, whitening toothpaste contains little or no bleaching agents but helps brighten your teeth by scrubbing away stains. These kinds of toothpaste are less likely to irritate or burn the gums if they have no hydrogen peroxide. You might experience some irritation if you brush too hard, but the ingredients themselves are unlikely to cause a problem.
Usually, tooth whitening products with bleaching agents contain either hydrogen peroxide or carbamide peroxide. A Cochrane study found that gum irritation is one of two common problems when using teeth whiteners with a higher concentration of bleaching agents. (Tooth sensitivity is the other problem.) Though, if used correctly, the irritation was temporary and mild.
Besides feeling a chemical burn, you'll recognise gum irritation during the whitening process if your gums develop white spots or parts of your gum turn white. Your gums might become inflamed, as well.