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Hydrogen Peroxide vs. Carbamide Peroxide: What's the Difference?

Teeth whitening is done with one of two active ingredients: carbamide peroxide or hydrogen peroxide. Some whitening products contain hydrogen peroxide and others contain carbamide peroxide. So what’s the difference?

What is the difference between hydrogen peroxide and carbamide peroxide?

Hydrogen peroxide alone is an effective whitening agent. Carbamide peroxide—also an effective whitening agent—contains hydrogen peroxide at a ratio of 1:3. For example, a product with 30% carbamide peroxide has about 10% hydrogen peroxide.

Does one work better than the other?

No! The good news is that hydrogen peroxide and carbamide peroxide both produce the same outstanding results. A study published in Journal of the American Dental Association showed that while carbamide peroxide appeared to produce slightly more dramatic results at first, ultimately products containing equivalent amounts of carbamide peroxide and hydrogen peroxide produced exactly the same results.1

Does one work faster than the other?

Yes and no. Hydrogen peroxide breaks down faster than carbamide peroxide, so it releases most of its whitening power within 30–60 minutes. Carbamide peroxide, on the other hand, releases about 50% of its whitening power in the first two hours and can remain active for up to six additional hours. 2

This means that products using hydrogen peroxide have shorter wear times. However, the number of days a person will need to use either one depends not on hydrogen peroxide vs. carbamide peroxide, but on the individual’s unique needs and rate of tooth color change..

Does one cause more sensitivity?

No. There is no noticeable difference in sensitivity, regardless of whether you are using a hydrogen peroxide or carbamide peroxide product. This was also noted in the same study that showed hydrogen peroxide and carbamide peroxide produced equally brilliant results.1

Does one cause more rebound?

No. Rebound is where the teeth appear lighter immediately after whitening, but then lose some brilliance after a short time has passed. Rebound has more to do with dehydration than peroxide levels. Whitening gels like Opalescence that contain higher water content help to prevent rebound caused by dehydration.

Does one have a longer shelf life?

Yes. Products with carbamide peroxide have a slightly longer shelf life than those with hydrogen peroxide, although when refrigerated, all peroxide products have an increased shelf life.

Both hydrogen peroxide and carbamide peroxide produce excellent results

You can feel great about using either a hydrogen peroxide or a carbamide peroxide product to whiten your smile. Both will produce the same high-quality results, with no difference in sensitivity or rebound. Opalescence has developed a complete line of carbamide peroxide and hydrogen peroxide whitening product to fit every lifestyle.

ProductAmount of HP or CP
Recommended Daily Wear TimeShelf Life
Opalescence Go, 6%6% Hydrogen Peroxide60-90 minutes/day
Opalescence PF Gels, 10%10% Carbamide Peroxide8–10 hours or overnight
Opalescence PF Gels, 16%16% Carbamide Peroxide4–6 hours


  1. Mokhlis GR, Matis BA, Cochran MA, and Eckert GJ. A clinical evaluation of carbamide peroxide and hydrogen p eroxide whitening agents during daytime use. JADA. 2000;131(9):1269-1277. www.jada.info/cgi/content/full/131/9/1269
  2. Haywood VB. Nightguard vital bleaching: indications and limitations. US Dentistry. 2006;October:2-8. Reprinted on www.vanhaywood.com/articles/