Ask a Skin Care Biologist #1

Q: Can long-term retinol make skin thinner?

Retinoids accelerate turnover and remodel the epidermis. Overuse, especially in non-severe acne, can disrupt extracellular matrix (collagen/elastin) organization and impair barrier—presenting clinically as thinner, more fragile skin. A gentler, pH-controlled exfoliation routine is preferred for long-term skin quality.

Q: Are preservatives dangerous, or protective?

Proper preservation is anti-aging: it prevents microbial contamination that triggers inflammation and acne. Broad-spectrum systems (e.g., phenoxyethanol under 2%) at appropriate levels protect skin; “preservative-free” products can become reservoirs for microbes, increasing irritation and breakouts.

Q: Is a ‘purge’ from non-exfoliating products real?

Only exfoliation (chemical or retinoid) reliably reveals underlying lesions—often perceived as a temporary flare. Non-exfoliating serums/creams that cause ‘purging’ are typically causing irritation or comedogenesis; that’s a breakout, not a purge.

Ask a Skin Care Biologist is a weekly Bioluminescence post where OUMERE’s CEO & CSO, Wendy Ouriel, M.S., answers your questions. Wendy is a cellular biologist with expertise in cellular aging, extracellular matrix biology, and the biology of skincare.

By Wendy Ouriel, M.S. • Updated Oct 12, 2025

I’m excited to launch this weekly column, inspired by the thoughtful questions we receive from OUMERE clients and Bioluminescence readers. Our goal is simple: strip away myths, junk science, and fear-based marketing—and replace them with biology-first explanations you can use.

Question: I’m in my early 40s and used retinol for ~10 years. My esthetician says my skin looks thinner than expected for my age and blames the retinol. Is that true—why would retinol thin skin?

— Emily K.

Answer:

Retinoids (vitamin A derivatives) accelerate epidermal turnover and reorganize epithelial architecture. Used short-term for severe acne, this remodeling helps decongest. Used chronically on otherwise healthy skin, the constant “rearranging” can disrupt the extracellular matrix (ECM)—the collagen/elastin/hyaluronan scaffold your cells secrete for structural integrity.

Why “thinner” skin can appear:

ECM disruption: Persistent turnover can outpace repair, weakening collagen/elastin networks.
Barrier fragility: Heightened reactivity, dryness, and visible translucency from impaired lipids.
Mechanical vulnerability: With less robust scaffolding, skin tolerates stress poorly and appears delicate.

OUMERE protocol instead of chronic retinoids: favor controlled, pH-appropriate chemical exfoliation and anti-inflammatory hydration:

No. 9 Daily Liquid Exfoliant (gentle daily turnover without perfume/essential oils).
UV-R™ Concentrate (anti-inflammatory hydration).
Serum Bioluminelle (stable, non-occlusive moisture lock).

Deep dive on sensitizers to avoid while rebuilding: Essential Oils Are Not Essential. Barrier-repair guide: Barrier Repair After Retinoid/Acid Damage.

Question: I heard preservatives are dangerous. Should I choose preservative-free skincare?

— Jason R.

Answer:

Proper preservation is anti-aging. Unpreserved or under-preserved water-containing products can rapidly accumulate bacteria, fungi, and their endotoxins—provoking inflammation, acne flares, and dermatitis. A broad-spectrum system at validated levels (e.g., phenoxyethanol < 2%) prevents contamination so your formula remains safe and stable.

Key points:

“Preservative-free” + water almost always means microbe-rich after opening.
Essential oils are not broad-spectrum preservatives and are sensitizing. See: our explainer.
Choose formulas in glass, fragrance-free, and with transparent safety testing.

To minimize irritation while maximizing protection, keep routines minimal and fragrance-free. Explore: The OUMERE Routine.

Question: I used No. 9 for 3 months. I saw a “purge” first—then my acne cleared completely. Why worse before better?

— Jessica L.

Answer:

“Purging” is best described as a temporary flare linked to exfoliation. Chemical exfoliants (and retinoids) remove compacted corneocytes and normalize turnover, which can unmask subclinical lesions and inflammation that had been hidden by surface buildup. As renewal normalizes and inflammation subsides, the flare resolves and clarity improves.

Important distinction: Non-exfoliating serums/creams cannot cause a true purge. If bumps appear after a non-exfoliant, that’s irritation or comedogenesis—i.e., a breakout, not a purge. Reassess ingredients (fragrance, essential oils, drying alcohols, heavy occlusives).

For sensitive or inflamed skin, begin with our step-by-step guide and introduce No. 9 once calm: Sensitive Skin: The Cellular Response. Biology behind acne and inflammation: Acne & Inflammation: Biological Origin.

References

Jeremy, A. H., et al. (2003). Inflammatory events in acne lesion initiation. J Invest Dermatol, 121(1), 20–27.
Layton, A. M., et al. (1998). Evolving inflammation in acne vulgaris. Exp Dermatol, 7(4), 191–197.
Kim, J., et al. (2002). TLR2 activation in acne. J Immunol, 169(3), 1535–1541.
Stettler, H., et al. (2017). Preservation, moisturization, and microflora. J Dermatol Treat, 28(2), 173–180.
OUMERE Lab: Hyaluronic Acid: Water-Binding Myth
OUMERE Lab: No. 9 One-Week Collagen & Complexity Findings

Related OUMERE guides & products:

Have a question for the next Ask a Skin Care Biologist? Email blog@oumere.com.

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Question: I’m in my early 40s and used retinol for ~10 years. My esthetician says my skin looks thinner than expected for my age and blames the retinol. Is that true—why would retinol thin skin?

Answer:

Question: I heard preservatives are dangerous. Should I choose preservative-free skincare?

Answer:

Question: I used No. 9 for 3 months. I saw a “purge” first—then my acne cleared completely. Why worse before better?

Answer:

References

OUMERE Skincare