Hydrogen peroxide will whiten your teeth because all whitening products contain it or at least a derivative of it. It does so by diffusing through the tooth and oxidizing all of the organic matrices. That is essentially how they make the teeth get whiter.

The difference between the various teeth bleaching products is that they differ in their concentration of hydrogen peroxide (HP). As you may have imagined, the professional grade ones typically contain a higher concentration of it. On the other hand, the over the counter products contain a lower concentration of HP.
You may be wondering if there was a difference in time for how long it takes hydrogen peroxide to whiten your teeth and the answer is yes. Basically the concentration of hydrogen peroxide has a big influence on how quickly you can whiten them. Although they all whiten via the same mechanism despite their strength level. The only difference is in just how expeditious it occurs.
We will go over and explain what is the fastest and slowest ways to get your teeth whiter with HP along with an estimate of how long it takes.
The fastest way to whiten with hydrogen peroxide
Professional in-office whitening with hydrogen peroxide can whiten your teeth in as little as an hour. This is absolutely the fastest way to get your teeth whiter and there isn’t a single OTC product that can match it’s speed.

A study by Nature found that all whitening products can potentially whiten your teeth to the same level regardless of the concentration. However, a higher concentration of hydrogen peroxide was found to whiten teeth faster. A less potent one will still get the same result but it simply takes a lot more exposure time. In other words you have to whiten for a longer period of time to get there.
Therefore, the quickest way to brighten your teeth color would be to get it done professionally at your dentist’s office. You can achieve the results that you’re looking for in about an hour.
This is why the treatment is only a single session. You can compare that to some of the OTC products which require you to whiten for 1-2 weeks straight.
Disadvantage for whitening quickly
It may seem fantastic that you can brighten your teeth in a single visit with a more potent gel but there are downsides to it. The stronger products usually elicit more severe tooth sensitivity.
If you’ve ever done an in-office treatment vs using whitening strips at home, you’ll know the difference. The strips typically don’t make your teeth too sensitive even after a week of whitening. The at-the-dentist treatment will leave you sensitive for a few days after finishing the procedure.
The slowest way to whiten teeth
If you’re using a whitening product with a low concentration of hydrogen peroxide, it can take weeks or even months for you to see any results. Individuals who try OTC products are typically forced to use less potent whitening gels since those are the only ones that are purchasable.

Studies have shown that even lower strength hydrogen peroxide products can potentially whiten your teeth to the same level as more potent ones. It is just that they take a LONGER period of time to achieve the same results.
Most individuals are not aware of this simple fact, which is why they think that their whitening is not working. The truth is that they’re using a lower strength method and it simply takes more time to observe a change in tooth shade.
In other words, they still work and you should keep on using them!
Advantage for whitening slowly
Despite taking weeks or months to see results with less potent products, where they shine is in their safety aspect. Hydrogen peroxide has been shown to be cytotoxic to the pulp of the tooth in high concentrations. On the other hand, the lower strength ones have been shown to just mildly irritate the pulp but it is reversible irritation.
What they found in studies was that you can make the teeth whitening process safer if you reduced the exposure time to a more potent gel. This is consistent with the fact that all in-office whitening treatments are only a singular session while the take home products you can whiten for 1-2 weeks straight.
The less potent material can be used for a longer period of time which is also why you can often whiten as you sleep with them. This is the basis for the customized take home trays that your dentist makes for you. Essentially you whiten your teeth while you sleep.
Disadvantage for doing it slowly
An often overlooked variable is that you have to deal with fending off saliva if you’re going to whiten your teeth slowly. Your saliva contains a lot of enzymes that can break down the hydrogen peroxide, thus rendering it less effective.
A study by the Journal of Oral Pathology & Medicine found that salivary peroxidase serve as the first line of defense against HP. They rapidly detoxify it so that it barely even enters your bodily system.
That is good for keeping your body safe but it is bad for the whitening gel since it is being broken down. Nonetheless, what that implies is that its not harmful for you to swallow while you’re doing the treatment.
If you’re whitening at home, we do have some tips on how to stop the saliva from pooling while you’re doing it.
How long do the results last?
According to a study done by the Journal of Esthetic and Restorative Dentistry, the whitening results can last for at least up to six months with a single treatment. This was done with a fairly low strength product of hydrogen peroxide that was only 3%. They used it for about 30 minutes three times a day for about 14 days total.
When they compared the results after the six month mark, they noted that the teeth were still whiter than when they started. This is great news because it means that at least you quite a bit of value out of the money that you spent on the treatment.
The unfortunate news is that they did not continue the study further than that so we don’t know how long teeth whitening truly lasts. However if we were to postulate, your dietary habits such as drinking staining beverages or eating staining foods would have an effect on the length of time.
You can also extend the results if you do touch up whitening sessions every month or so.
Is it even safe to whiten your teeth?
It is safe to whiten your teeth because there has been many clinical studies on its long term effects. In fact, there was one study by JERD where a patient with severe tetracycline staining on their teeth used a 10% carbamide peroxide solution daily. They continued this every day for an entire six months.
They did a re-evaluation after 7.5 years and noted that there were no clinically significant problems. Therefore there are no long term side effects from long term whitening.
Of course you also have to be cognizant that this is with a lower concentration of the bleaching gel.
The Verdict – How long does hydrogen peroxide take to whiten teeth?
Hydrogen peroxide can whiten your teeth in as little as an hour but it can also take a few weeks to see results. The speed that it takes you to notice a change is highly dependent upon the concentration of the hydrogen peroxide in your gel.
The stronger the gel, the faster the results. The vice versa is also true in that the weaker the gel the slower the results. This is why the in-office results are usually expeditious compared to the take home products.
Just to reiterate, many people are unaware but regardless of the strength of the whitening material, they can all potentially whiten your teeth to the same level. It’s simply that less potent materials require a lot more time to do so.
What we’re trying to say is, don’t give up even if you’re not seeing results. Preserve and keep on going. You will eventually get the results that you want.