If you forget to put your teeth whitening gel in the fridge when it's supposed to be refrigerated, it will lose some of its potency. However, not all of the bleaching gels require refrigeration so it may be okay.
Therefore, the question you should be asking is... Does your whitening product require refrigeration or does it not? You should read the label carefully.
Teeth whitening gels that require refrigeration
Not all teeth whitening gels need to be refrigerated because some brands don't require it.
Out of the three most popular whitening brands by dentists, only the ZOOM take home kit does not require refrigeration. The instructions specifically say to NOT put it in the fridge or freezer. Apparently room temperature is sufficient.
The other two brands, KoR and Opalescence both recommend refrigeration for their products.
Therefore, whether or not you need to put your bleaching gel into the fridge would depend on the brand that you're using. If the instructions say to put it in the fridge then in it should go. If it doesn't require it, then you can leave it out at room temperature.
What happens if you don't refrigerate whitening gel
There are no adverse effects for not refrigerating whitening gels that do not require it. However, if you don't refrigerate the gels which do require it, there will be consequences.
Decreased effectiveness. Whitening gel begins to breakdown when not refrigerated. That means there is a chance it may be completely inactive by the time you use it on your teeth.
Decreased shelf-life. When stored in a cool environment, it blocks the breakdown of peroxide which extends the shelf-life of the bleaching gel. It lasts longer when kept in the fridge and not on the counter.
Increased teeth sensitivity. Non-refrigerated gels will breakdown and become more acidic. This translates to greater teeth sensitivity while you're whitening.
Heat exposure decomposes peroxide
When hydrogen peroxide is exposed to heat, it will begin its decomposition reaction.
What that means for you: Unfortunately, if the peroxide is decomposing when it is NOT on your teeth, you're essentially wasting whitening material.
You want the reaction to take place on your enamel because it is the intermediate steps in the decomposition which bleaches your teeth. The free radicals produced during these in between steps are what oxidize the stains in your teeth.
However, the free radicals don't last forever. They quickly convert to the final products of the reaction which are oxygen and water. As we all know, O2 and H2O do absolutely nothing for whitening your teeth.
Therefore, if you've ever experienced using whitening products that did nothing for your teeth, perhaps they were unrefrigerated for an extended period of time. The peroxide probably completely decomposed and there is no more effective bleaching left in it.
How long can whitening gel be left out?
Teeth whitening gel that has been left out for a day will most likely still be okay. However, the longer that you leave it out unrefrigerated, the less effective it will be. There is a direct correlation between the exposure to heat and how effective it still is.
If it's been sitting out at room temperature for a week or more, we dare say that it has probably lost all of its whitening potency. You can still try to use it but if your teeth aren't whitening, you may need to purchase a fresh batch of the gel.
How to tell when it has gone bad
It may be difficult for you to tell just by looking if whitening gel has gone bad. There really isn't a way to know until you actually try using it on your teeth.
Signs of ineffective whitening gel:
Teeth aren't whitening. If you don't notice your teeth lightening in color even after a few days of use, the gel may have gone bad.
Teeth feel extra sensitive. When bleaching gels go bad they tend to turn very acidic due to peroxide breakdown. Using this on your teeth will cause them to feel extra sensitive because you're essentially putting acid on your teeth.
Those are the two signs which may indicate that your blunder of leaving the whitening material out of the fridge may have caused it to go bad.
Gel for teeth whitening that requires refrigeration should be stored in the fridge at all times. Please do not take it out when you are not using it. It should stay stay in a cool environment 24/7 when possible.
You should only take the gel out when you are using it.
How long does teeth whitening gel last in the fridge
When the tooth bleaching gel has been stored properly in the fridge, it should last until the expiration date as stated on the package. There should be a best by or use by date on the label.
It is only if you don't store it properly that the gel can potentially go bad before the expiry date has even been reached. Therefore please do your best to follow the directions.
Can I freeze it?
The various whitening manufacturers do not say that you should freeze the gels. It should be refrigerated only as per instructions.
However you may be interested to know that hydrogen peroxide does not freeze below 32 degrees fahrenheit. It's freezing point is a bit below that, at around negative 2 celsius.
Can I still use unrefrigerated teeth whitening gel?
Unrefrigerated teeth whitening gel can still be used but it may not give you the results that you want. The biggest disadvantage is the decrease in effectiveness when exposed to heat.
Increased teeth sensitivity
Decreased whitening efficacy
Harmful to enamel
Overall, you may be wasting your time by using ineffective teeth whitening material.
Forgetting to put teeth whitening gel in the fridge will cause it to decompose and lose its effectiveness. It won't happen all at once but it will occur slowly. The longer it is left unrefrigerated, the less potent it'll be.