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How to whiten teeth with hydrogen peroxide 
Brush with a whitening toothpaste. 
Purchase a whitening toothpaste with hydrogen peroxide at your local pharmacy or grocery store. Brush with the product at least twice daily for at least one month to see results.
Buy a product with at least 3.5% hydrogen peroxide, which is the standard amount. Be aware that the more hydrogen peroxide in a product, the likely it is to make your teeth sensitive.