How can hydrogen peroxide in off-the-shelf and professional teeth whitening products damage the teeth?

LED or any form of teeth whitening that is not performed by a dentist practicing in a licensed dental clinic is not subjected ANY oversight and regulations by national health and safety authorities. You are essentially at the mercy of the manufacturer and the service provider and any claims that they make about their products and services.

Hi, Benzoyl peroxide helps to treat the painful inflamed lesions of acne by killing the bacteria that causes them. If there are no more active inflamed acne, you can consider stopping its use. However, the non-inflamed comedonal acne i. e the whiteheads and blackheads which are the precursors of inflamed acne continue to form even after the inflammation has subsided, so these have to be controlled to prevent acne from relapsing. The best control for these non-inflamed acne comedones is the regular use of topical tretinoin or adapalene at night over acne-prone areas.