Teeth-whitening side effects.

- Causes / Solutions / Remedies - for bleaching treatment triggered tooth sensitivity, gum or throat irritation and uneven whitening.

Some of the most common side effects associated with tray-based whitening technique that utilizes a peroxide-based whitener are: 1) Tooth sensitivity. 2) Gum irritation. 3) Sore throat. 4) Uneven whitening.

This page outlines what aspects of the bleaching process tend to cause these problems, and common treatments or solutions for them.

A) Tooth sensitivity.

This is the most-reported side effect. Studies have found that roughly 1/2 to 2/3 rds of all people who bleach their teeth will notice some type of tooth sensitivity during their treatment period.

What you may notice.

What most people experience is usually just transient (one or a few days). It can be mild to moderate in intensity.

It can take the form of:
  • Thermal sensitivity. - A response to hot and cold temperature variations such as those created by foods and beverages.
  • Sensitivity to air. - Like when a person breathes through their mouth.
  • Generalized tooth discomfort.


Who's at risk?

There's no way to know precisely who will encounter this problem (or to what degree). But if you notice either of the following, there's a good chance that you will.

  • Prior to starting your treatments you already notice some sensitivity to hot and cold extremes.
  • You notice thermal sensitivity after getting your teeth cleaned. (For all people, it's best to wait at least 2 weeks after a dental cleaning before starting whitening treatments.)

Solutions / Treatments.

a) Put your treatments on hold.

In a majority of cases, simply stopping all whitening activities for a few days will allow your teeth to return to normal.

Once things have settled down, consider resuming your process but using a schedule that reduces your exposure to the whitener. This could be either shortening the duration of your sessions, or performing them less frequently (like every other day).

Choosing either method will mean that your overall whitening process will take a longer time frame to complete. But if that's what it takes to keep you comfortable, then so be it.

Tip: Despite a change in your treatments, you should still be able to reach the same level of whitening results.

That's because the lightening effect you achieve is due to your total (cumulative) exposure to the whitener. Whether this is over a relatively shorter or longer time period doesn't matter.

Syringes of 10% carbamide peroxide tooth whitener.

10% carbamide peroxide whitener makes a good choice.

b) Use a lower concentration whitener.

Your potential for experiencing tooth sensitivity will directly correlate with the strength of the whitener you are using. The higher its peroxide content, the more likely this side effect will occur.
As a solution, switch to a gel that has a lower concentration. This should be simple enough to do. The product lines of all manufacturers include whiteners of varying strength. We've seen carbamide peroxide gels that range from 10 to 44%.
Tip: A 10% carbamide peroxide bleaching gel is typically considered the basic, entry-level whitener. One that produces good results yet triggers minimal side effects.

You get the same results (reach the same whitening endpoint) when using a lower concentration gel, it just takes more individual treatments.

c) Use toothpaste "for sensitive teeth."

Using "desensitizing" toothpaste can help to control side effects.

This type of product, frequently labeled as "toothpaste for sensitive teeth," can be found on the dental aisle of just about any store that sells dental goods. The active ingredient is usually potassium nitrate or, less frequently, fluoride. (Related page: The best toothpastes for treating tooth sensitivity.)

Toothpaste for treating sensitive teeth.

Look for toothpaste that's for "sensitive teeth."

The idea is that you use the anti-sensitivity toothpaste in place of your regular one for days, or even weeks, as it creates its palliative effect. (Prescription-strength fluoride toothpaste or gel can be used in a similar fashion.)

Tips: The formulations of some whitening gels include potassium nitrate or fluoride. Even so, their use is seldom as effective as the extended use of desensitizing toothpaste.

  • Some dentists recommend using anti-sensitivity toothpaste for 2 weeks before initiating treatments as a way of minimizing the potential for side effects.
  • Another strategy is to place the toothpaste in your bleaching trays and wear them for 30 minutes a day, the entire week before initiating treatments.

d) Anti-inflammatory medicines.

The use of a non-steroidal anti-inflammatory (NSAID) medication, like ibuprofen (Motrin®) can help to minimize or control bleaching-induced tooth sensitivity. (Check labeling to make sure that this type of drug is appropriate for you.)

It works by counteracting the temporary inflammation caused by the whitener as it penetrates through your tooth to its nerve tissue.

Tip: Take the medication 30 minutes or so prior to performing your treatments, that way it's already in your bloodstream when the inflammation reaction first starts.

B) Gum irritation.

Gum tissue irritation is another frequently encountered side effect. This sensitivity can be caused either by the whitener or the bleaching trays themselves.

Causes / Solutions.

a) Use a lower concentration whitener.

Just as with tooth sensitivity, a person's potential for experiencing gum irritation is directly related to the concentration of peroxide in the whitener they are using.

As a solution, switch to a lower concentration one (see above).

Tip: A lower risk for side effects is why our pages emphasize the use of a 10% carbamide peroxide gel with tray-based technique.

b) Halt your whitening treatments.

Noticing minor residual gum irritation after completing a whitening session can be considered normal. But this sensitivity should disappear long before initiating your next treatment.

If not, it only makes sense to stop your bleaching activities until it does. Then, once things have settled down, consider reducing your exposure to the whitener by either bleaching less frequently or for shorter periods of time (see above).

A custom-made bleaching tray.

The edges of a custom tray end just short of the user's gum line.

c) Use "custom" trays.

Custom trays are bleaching trays that have been made specifically for the person who will wear them. They're fabricated in a dental laboratory on models of your teeth.
  • These are the type you get with a dentist-dispensed system.
  • Some online sources may offer dental laboratory services through which they may be obtained.
They're trimmed so they fully cover over the surface of each tooth, yet their edge falls just short of the gum line.

This contouring helps to minimize the contact of the whitening gel with soft tissues. And it prevents the edge of the trays from rubbing against your gums and irritating them.

A stock bleaching tray.

Stock trays typically cover over the user's gums.

Stock vs. custom trays.

The bleaching kits you buy in stores come with "stock" trays.
  • If they don't fit well, they may cause gum irritation.
  • Their overextended edges can irritate gums or hold whitener against them.

Tip: Using stock trays doesn't mean you absolutely will experience gum irritation. It just makes it more likely.

Excess tooth whitener should be wiped away.

After inserting your trays, wipe away any excess gel.

d) Wipe away any excess gel.

Another thing you can do to help to prevent gum irritation is to wipe away any excess gel that escapes from your trays after they've been inserted. You can do this with either your finger or a toothbrush.

Tip: Make sure to rinse your hands or toothbrush after doing so. Bleaching gels can damage other objects they come into contact with, or irritate other body tissues.


C) Throat irritation.

It's inevitable that during every single whitening session you'll swallow some whitener. And as you do, it's possible that it will irritate the tissues that line your throat.

Small dabs of whitener are placed in the tray.

Using only dabs of whitener helps to minimize throat irritation.

Solutions / Treatments.

In the majority of cases, the irritation will resolve on its own long before your next session.

If the irritation persists, stop performing sessions and let things settle down. Then once they have, experiment with alternatives such as using a lower concentration whitener or performing treatments less frequently (see above).

A bleaching tray reservoir.

Custom trays with reservoirs help to minimize throat irritation.

  • Dispensing only the bare minimum of whitener that's needed can help to minimize this side effect.
  • Throat irritation is more likely to occur when treatments are performed overnight as opposed to during waking hours (when you have an opportunity to spit out).
  • Using custom trays designed with reservoirs (extra spaces on the front side of the teeth) help to minimize the amount of whitener that's swallowed.



D) Uneven or spotty whitening.

A phenomenon sometimes occurs where teeth being bleached take on an uneven splotchy appearance.

This side effect is more likely to be associated with the use of whiteners that have a comparatively higher peroxide content.

Solutions / Treatment.

In most cases, the color variation will start to show during the first week of bleaching treatments and then resolve on its own (typically within a week or so as further sessions are performed).

Possible causes:

Using stock bleaching trays.

It's possible that the use of stock bleaching trays (as opposed to custom ones, see above) is the cause of uneven whitening.

  • The trays may not cover over the entire front side of each tooth, thus resulting in treated and untreated portions of the tooth.
  • Any ill-fitting aspect of a stock tray may not hold the whitener in full contact with some teeth, thus leaving them under-exposed.
  • (In a similar fashion, due to their standardized shape whitening strip products sometimes lack the ability to fully cover over the teeth being treated and therefore produce uneven whitening.)

Because a tooth will ultimately reach a point at which it will lighten no further, the hope is that continued treatments will allow all parts of the tooth to finally reach this end-stage and the color of all portions will match. (This may or may not be a possibility, simply depending on the nature of the tooth itself. Additionally, if the coverage of the tray, or strip, is especially deficient this may not be possible.)

Uneven whitening due to the tooth's anatomy.

Different portions of a tooth have a different internal makeup, and this may affect the rate (evenness) with which it lightens. This effect may be especially noticeable with front teeth where:

  • The thickness of the 1/2 of the tooth closest to its biting edge may be almost entirely enamel.
  • In comparison, the composition of the 1/2 of the tooth closest to the gum line is one where the bulk of the tooth is composed of (comparatively dark) dentin that has an enamel covering over it.

In this situation, whatever lightening effect a single bleaching session produces will be less profound for the 1/2 of the tooth closest to the gum line because the darker appearance of the dentin underneath will still show through. The all-enamel portion of the tooth won't have this darker layer to mask, and therefore appear whiter more rapidly.

The common (hopeful) outcome for this uneven appearance is one where the biting-edge portion of the tooth ultimately reaches a point where it whitens no further. As treatments are continued, the shade of the gum-line portion of the tooth continues to lighten and eventually (hopefully) evens things out.


Let your dentist know.

When experiencing side-effects, it's a good idea to consult with your dentist.

Transient problems are commonplace. But for peace of mind, and especially in those cases where symptoms persist or intensify, it's best to let them pass judgment on your situation.

How intense can whitening side effects be?

The side effects caused by a tray-whitening process may be intense enough that it has to be discontinued. But this is the exception, not the rule. In most cases what a person encounters is only minor in nature.

For most people, side effects are a non-issue.

One study evaluating this issue (Leonard, 1998) asked participants to rate the level of discomfort caused by their tray-bleaching process on a scale from 0 to 10, with 10 being the most painful. Most respondents rated their experience as being a 1 or 2.


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