A possible side effect of whitening. Bleaching can cause a temporary increase in sensitivity to temperature, pressure and touch. This is likeliest to occur during in-office whitening, where higher-concentration bleach is used. Some individuals experience spontaneous shooting pains ("zingers") down the middle of their front teeth. Individuals at greatest risk for whitening sensitivity are those with gum recession, significant cracks in their teeth or leakage resulting from faulty restorations. It has also been reported that redheads, including those with no other risk factors, are at particular risk for tooth sensitivity and zingers. Whitening sensitivity lasts no longer than a day or two, but in some cases may persist up to a month. Some dentists recommend a toothpaste containing potassium nitrate for sensitive teeth.
