Are proven ingredients guaranteed to work?

Many people think that as long as they use only the treatments backed by plentiful scientific evidence the results are virtually guaranteed. Such optimism, however invigorating, is unfounded. Due to variations in individual skin chemistry, only a percentage of people respond to even proven treatments. Also, a proven ingredient has a chance to be effective only if it is delivered deep enough into the skin in sufficient amounts. This, in turn, depends on whether the product is properly formulated (in terms of concentration, stability, skin penetration, etc.) and whether you apply it correctly. (See our article on how to apply skin care products.)

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