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Why are oil and water not related?

Asked by Anson

Dr Schultz, I have a quick question. Why are oil and water not related? Isn’t sebum supposed to reduce TEWL and thus “hydrate” the skin?

Anson answered
    Dr. Schultz 1.86K Rep.

    Oil and water are not related in their formation or production. Oil glands make oil, and water (sweat) glands make water. And you are absolutely correct that one of the roles of sebum is to coat the skin and thereby reduce TEWL (Transepidermal Water Loss), which effectively “hydrates” the skin by preventing loss of existing surface moisture. That is a fact of normal physiology which has been abused by skincare manufacturers. They promote oil as a “moisturizer” and unfortunately trick people who have dry (lack of water) skin into coating their skin with oil-containing products to seal in their existing moisture, which may or may not be effective. But this also runs the risk of clogging the oil glands of people who have a normal amount of oil, let alone causes acne outbreaks in people with both dry and oily (combination) skin. The best way to treat dry skin is with oil-free, water-based moisturizers that restore and correct the deficient water content without risking collateral damage to the oil glands.

    Dr. Schultz answered

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