SKINCARE MYTH BUSTED : THE TRUTH ABOUT THE RETINOID SANDWICH

💪 Dear Wonderwomen and Supermen,

Is applying moisturizer before or after your retinoid a dermatological heresy ? For years, the “sandwich” method has divided experts and patients alike: some swear by it to reduce irritation, while others fear it compromises treatment efficacy.

For the first time, a rigorous study sheds light on this popular practice with scientific data. The result? A surprising twist to what we thought we knew.

If you’re passionate about skin health and optimal aging, this edition is a must-read. Keep going—now’s the time to separate myth from fact.

SPOTLIGHT

The ongoing debate between retinoid efficacy and application comfort takes a new turn, thanks to a study presented by Dr. Asha Patel Shah at the AAD 2025 conference.
For the first time, researchers quantified the impact of different hydration methods (“open” vs. “full” sandwich) on the biological activity of retinoids. By testing combinations on human skin biopsies, the study showed that the popular “open sandwich” method—moisturizer applied either before or after the retinoid—does not reduce the treatment’s molecular efficacy. A crucial insight for skincare professionals and longevity-focused skincare enthusiasts.

The Details :

• Study at a glance : Dr. Shah’s team tested retinoids combined with two types of moisturizers (gel and water-based cream) on skin biopsies. Result: key gene activity (HBEGF) remained intact with the “open sandwich”, but dropped sharply with the “full sandwich.”

• Goal : tolerance without compromise : Moisturizers are often used to limit retinoid irritation. This study confirms the practice is safe—and doesn’t compromise therapeutic effect—when applied correctly.

• “Full sandwich” not recommended : Applying moisturizer both before and after retinoid use reduces its activity by up to threefold. This may be due to dilution and a barrier effect on skin penetration.

• Innovative formulas tested : Moisturizers included natural moisturizing factors and a biomimetic matrix. They demonstrated excellent tolerance in patients with sensitive skin (acne, rosacea, atopic dermatitis).

• Direct clinical impact : These findings provide scientific backing for dermatological recommendations and enable more precise personalization of skincare routines, based on individual tolerance and skin type.

Key Takeaway :

Strategic hydration does not reduce retinoid efficacy—as long as you avoid the double application. This study resolves a major uncertainty in anti-aging skincare and helps balance effectiveness with comfort. It marks a key step toward more personalized, scientifically validated dermatology. For skincare professionals, this offers a valuable tool to educate and guide patients with precision.

HYPE OR FACT ?

💭  Powdered collagen makes you look younger

✅ FACT… but with nuance

Hydrolyzed collagen peptides have shown, in several clinical studies (notably a 2019 study in the Journal of Drugs in Dermatology), modest but real effects on skin hydration, dermal density, and wrinkle appearance after 8 to 12 weeks. That said, it’s not a dramatic transformation—no magic powder, no fountain of youth. Just a small, science-backed boost.

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