Over time, foods, drinks and medications can stain your teeth, causing them to appear dingy or dull in color. Tooth whitening offers a solution to this problem by removing stains and/or bleaching tooth enamel, revealing a white smile. However, tooth bleaching can be accompanied by some side effects. Knowing what these are and how to prevent them can help you to safely achieve a whiter, brighter smile.

Tooth whitening can be performed in a variety of ways, and advancements in the technique have even made at-home whitening possible. Dentists typically perform tooth whitening by applying a peroxide-based solution to the teeth, or using a laser on the teeth, according to Doc Shop. At-home bleaching kits often contain lower concentrations of bleach than those used during a dental office whitening treatment.

Teeth whitening, though generally considered to be a safe procedure, may include side effects such as increased tooth sensitivity and discomfort, gum pain and discomfort, sore throat, or white patches on the gum line, according to the British Dental Health Foundation. If you do experience these effects, they should only last a few days following your treatment.

Tooth sensitivity or pain following whitening occurs when the nerves in your teeth and gums become disturbed, according to the Cosmetic Dentistry Center, a Texas-based cosmetic dentistry practice. Over time, your teeth’s protective enamel over these nerves may wear down. Because a whitening treatment can bleach your teeth’s enamel, the treatment can potentially affect the enamel and nerves, making you more sensitive or causing pain. The nerves typically are not severely affected, and become less sensitive in a few days. However, if your pain continues or increases, see your dentist.

Some people may be more likely than others to experience pain following tooth whitening. These groups should exercise caution and discuss risks with a dentist prior to undergoing a bleaching treatment. These include those who already experience tooth sensitivity issues and smokers, according to Family Gentle Dental Care, a Nebraska-based dental practice. Because smoking damages gums and teeth, applying peroxide to these areas can have a negative effect. Also, those with sensitivity experience pain with tooth whitening at a higher percentage than those who do not have prior sensitivity issues. A dentist may recommend a lower peroxide concentration if you have sensitive teeth.

Over-whitening your teeth — using whitening products so frequently that tooth enamel is affected — will make you more likely to experience pain with tooth whitening. This is because whitening exposes small areas in the enamel that can make the nerves more vulnerable. When you apply these whitening treatments frequently, your nerves are exposed more often. For this reason, it may be wise to wait several months to a year between whitening treatments.