Retinol is the most well-documented anti-aging active ingredient in dermatology. Derived from vitamin A, it stimulates collagen production, accelerates cell renewal, and reduces hyperpigmentation spots. If you're wondering if it's really worth incorporating into your routine, the answer is yes, provided you choose the right concentration and format for your skin.
In this article, you'll find the benefits of retinol backed by clinical studies, the mistakes that cause irritation, and why Korean formulas with bakuchiol are a game-changer for skin starting out.
Are you looking directly for a Korean retinol serum? Some By Mi offers 0.1% formulas combined with bakuchiol, dermatologically tested and designed for reactive skin. (view the Some By Mi range)
What exactly is retinol, and why is everyone talking about it? 🔬
Retinol belongs to the retinoid family, derivatives of vitamin A. Discovered in 1931 in mackerel liver oil, it is now synthesized in laboratories and used at concentrations ranging from 0.025% to 0.3% in leave-on cosmetic products.
After application, retinol undergoes two enzymatic conversions to become retinoic acid, its active form. It is this retinoic acid that interacts with RAR receptors (retinoic acid receptors) and RXR receptors (retinoid X receptors) in skin cells, triggering a cascade of signals that regulate the expression of certain genes involved in cell renewal.
In concrete terms: it accelerates the life cycle of your skin cells, stimulates the synthesis of collagen and elastin, and unclogs pores. This triple mechanism makes it such a versatile active ingredient.
Expert's tip: Many start with too high a concentration to "see faster results." This is the most common pitfall. A 0.3% retinol on unaccustomed skin generates redness, flaking, and often leads to abandoning the active ingredient after two weeks. Starting at 0.025% or 0.05%, twice a week, then gradually increasing over 8 to 12 weeks helps to avoid rebound effects and achieve lasting results.
Benefit 1: Retinol really reduces wrinkles, and studies prove it 📊
Skin aging results from a double pressure: internal biological factors (decrease in collagen, elastin, and hyaluronic acid) and external aggressions (UV, pollution, tobacco). Retinol acts on both fronts.
The most cited study on the subject was conducted by Majmudar and his team in 2015. 41 women aged 35 to 55 applied a 0.1% retinol serum for 12 weeks. The results measured by confocal microscopy were as follows: an average increase of 46.28% in epidermal thickness, a reduction in cheek wrinkles of 63.74%, and a reduction in wrinkles around the eyes of 38.74%.
The mechanism is twofold. First, retinol stimulates fibroblasts to produce more type I collagen and elastin, which redensifies the dermis. Second, its antioxidant properties neutralize free radicals, unstable molecules generated by oxidative stress that degrade structural proteins and accelerate aging.
The realistic timeframe to observe a visible improvement in wrinkles is 8 to 12 weeks of regular use. Effects on texture (skin texture, smoothness) generally appear earlier, around the 4th week.
Benefit 2: Acne, blackheads, and imperfections, does it really work? 🎯
Retinol is an ally for acne-prone skin, but not for the reasons often believed. It is not an antibacterial. Its action involves regulating keratinocyte differentiation: by accelerating epidermal cell renewal, it prevents dead cells from accumulating and clogging pores.
Concrete result: fewer closed comedones (whiteheads), fewer blackheads, and skin whose pores remain cleaner over time. Retinol does not cause epidermal exfoliation like a chemical exfoliant; it simply accelerates the natural renewal cycle.
A study by Natakankitkul and his team (2009) compared the efficacy of a 0.2% retinol formulation, a vitamin C derivative (5% sodium ascorbyl phosphate), and the combination of the two on 45 participants with acne for 8 weeks. The most significant reductions in the number of acne lesions were observed in the group that received the retinol + vitamin C combination.
Note: prescription retinoids (adapalene, tretinoin) are significantly more powerful for severe inflammatory acne. Cosmetic retinol is relevant for skin prone to mild to moderate acne, or for maintenance after dermatological treatment.
Benefit 3: Dark spots and uneven skin tone, retinol as a skin tone unifier 🌟
Hyperpigmentation results from localized melanin overproduction. It can be caused by UV exposure, post-acne inflammatory processes (red or brown marks that persist after a pimple), or skin aging. Retinoids act on this mechanism in two ways.
First way: accelerating cell renewal allows for faster elimination of melanin-laden cells in the stratum corneum. Second, retinoids inhibit the expression of tyrosinase, the key enzyme in melanogenesis, as well as TRP-1 and TRP-2 proteins.
A study by Erkiert-Polguj and his team (2020) evaluated 0.3% and 0.5% retinol formulations on 37 volunteers with signs of photoaging for 12 weeks. A significant decrease in hyperpigmentation was measured for both concentrations, with comparable results between 0.3% and 0.5%, suggesting that concentration is not the limiting factor beyond a certain threshold.
For recent post-acne spots, combining retinol with niacinamide (5 to 10%) enhances the unifying effect. This is precisely the angle of Korean formulas, which often combine several active ingredients at moderate concentrations rather than a single active ingredient at high doses.
If you want to know more about Korean ingredients that pair well with retinol, the article on the COSRX range discusses in detail the anti-blemish active ingredients that complement this type of routine.
Why Korean retinol formulas are different from classic formulas 🇰🇷
Korean skincare has approached retinol with a philosophy different from Western cosmetics: rather than maximum concentrations for quick results, it favors progressive concentrations combined with soothing agents to minimize irritation.
The retinol + bakuchiol combination is the best example of this approach. Bakuchiol is a plant-derived functional retinoid (extracted from Psoralea corylifolia seeds) that activates the same receptors as retinol without the irritating effects. A study published in the British Journal of Dermatology demonstrated that 0.5% bakuchiol is comparable to 0.5% retinol for wrinkle reduction and hyperpigmentation, with significantly less flaking and stinging.
The Some By Mi Retinol Intense Reactivating Serum illustrates this positioning: 0.1% retinol combined with bakuchiol (1,000 ppm), non-comedogenic formula, dermatologically tested. It is the ideal entry-level retinol for skin that has never used this active ingredient, or for sensitive skin that has had bad experiences with classic Western formulas.
The most common mistakes with retinol (and how to avoid them) ⚠️
Retinol purge, chronic irritation, and persistent redness are not inevitable. In most cases, they are linked to identifiable usage errors.
Mistake 1: Using it every night from the start. The recommended protocol is 2 times a week for the first 4 weeks, then 3 times the following week, then gradually every night. The skin's liver (the skin barrier) needs time to adapt so as not to react to accelerated cell renewal.
Mistake 2: Skipping moisturizer after application. Retinol increases transepidermal water loss (TEWL) in the first few weeks. Applying a rich moisturizer after retinol serum does not decrease its effectiveness, but significantly reduces discomfort and the risk of irritation.
Mistake 3: Using it morning and night. Retinol degrades in light and sensitizes the skin to UV. It should only be used in the evening, followed by an SPF the next morning without exception.
Mistake 4: Layering it with strong acids on the same night. Combining retinol and AHA or BHA in the evening doubles the irritating potential without doubling the benefits. These exfoliating active ingredients work on alternating nights.
To build a complete routine incorporating retinol, the page dedicated to the secrets of smooth Korean skin provides an overview of the order of active ingredients and winning combinations.
Retinol and sensitive skin: concentration, timing, alternatives 🌿
Sensitive skin can use retinol, but with an adapted protocol and the right formula choices.
The recommended starting concentration for sensitive skin is 0.025% to 0.05%, once a week for the first two weeks. European Regulation (EC) No 1223/2009 limits the concentration of retinol in leave-on cosmetic products to 0.3%, which is already an effective dose for most skin types.
The "sandwich" technique is particularly suitable for sensitive skin: apply a light layer of moisturizer, then retinol, then a second layer of moisturizer. This buffering method slows penetration and reduces the risk of reaction without compromising long-term efficacy.
For truly reactive skin, bakuchiol alone (0.5%) for 8 to 12 weeks constitutes an excellent "pre-adaptation" period before introducing retinol. Clinical data show comparable improvements for the most sensitive skin types that poorly tolerate the synthetic molecule.
The use of retinol is contraindicated during pregnancy and breastfeeding, regardless of the format or concentration.
What to remember about the benefits of retinol 💡
Retinol remains the most well-documented anti-aging active ingredient in cosmetics: its effects on collagen, imperfections, and hyperpigmentation are proven by reproducible clinical studies. The key is in progression, not concentration.
Korean formulas, especially those combining retinol and bakuchiol, offer a gentler and more tolerated entry than classic high-concentration formulas. For skin that has never used retinol, this is the smartest starting point.
Three points to remember before starting: start with a low concentration (0.025 to 0.05%), use it only in the evening, and always apply an SPF in the morning. It is not the active ingredient itself that irritates, but its use without these three precautions.
To find the retinol serum suitable for your skin type, the Some By Mi range offers progressive formulas designed for Korean skin, therefore tested on reactive profiles. (view Some By Mi retinol products) If you are not yet sure of your skin type, the free Holy Skin diagnostic will give you a personalized recommendation.
