What is the epidermis, and why is it essential?
The epidermis is the outermost layer of the skin, averaging about 0.1 mm in thickness (up to 1.5 mm on the soles of the feet). It is composed primarily of keratinocytes organized into several layers (basal, spinous, granular, and stratum corneum), as well as melanocytes (pigmentation), Langerhans cells (skin immunity), and Merkel cells (mechanoreceptors). Its barrier function protects the body from external aggressors (UV rays, pollutants, microbes, transepidermal water loss). The epidermis is constantly renewing itself (approximately every 28 days in young adults), a process that slows with age. Preserving it is the central goal of any sound skincare routine.
How can you maintain the health of the epidermis?
An effective routine is based on three complementary pillars:
- Gentle cleansing morning and night, without harsh surfactants, using a syndet or a cleanser with a pH close to that of the skin (around 5.5). Avoid scalding water and vigorous rubbing.
- Dailymoisturizing tailored to your skin type, to maintain the suppleness of the stratum corneum and limit transepidermal water loss.
- Consistentsun protection in the morning (SPF 30 or 50 depending on the situation): this is the best-documented anti-aging and skin cancer prevention measure.
Supplements tailored to your skin profile: targeted serums (antioxidants, niacinamide, peptides), nourishing evening treatments, quality sleep, and a varied diet.
What ingredients nourish the epidermis?
Several cosmetic active ingredients have been the subject of encouraging studies:
- Antioxidants: stable vitamin C (L-ascorbic acid, derivatives), vitamin E, niacinamide, plant polyphenols. Help neutralize environmental free radicals.
- Hyaluronic acid: a major humectant that attracts and retains water in the stratum corneum.
- Ceramides: lipids that make up the intercellular matrix, supporting the integrity of the hydrolipidic film.
- Niacinamide (vitamin B3): regulates sebum, visually minimizes the appearance of pores, and soothes redness.
- Bioactivepeptides: help maintain skin suppleness.
- Cosmetic retinol: supports superficial skin renewal. This is distinct from medical retinoids (prescription-only, contraindicated during pregnancy due to their teratogenicity).
- Essential fatty acids (omega-3, omega-6) obtained through diet: have an overall beneficial effect on the quality of the hydrolipidic film.
How can you identify skin in distress?
Several signs indicate a skin imbalance:
- Persistent dryness, tightness, and a feeling of discomfort.
- Flaking, roughness, red patches.
- Itching, stinging, or a burning sensation upon application of products.
- Increased sensitivity to products that are usually well tolerated.
- Diffuse hyperpigmentation or recent localized spots.
- Prolonged inflammation, evolving lesions, oozing.
A consultation with a dermatologist is recommended in cases of worsening symptoms, suspicious lesions (changes in the shape, color, or size of a mole), symptoms that persist despite a simple skincare routine, or when the condition impacts quality of life. A dermatologist can make an accurate diagnosis (eczema, seborrheic dermatitis, rosacea, psoriasis, other skin conditions) and recommend appropriate treatment.
What are some recent innovations in skin care?
Dermatology and cosmetology are evolving rapidly:
- 3D skinbioprinting: a technology primarily used in research and development (in vitro models as alternatives to animal testing, efficacy and tolerance testing); not yet a common clinical practice in humans.
- Connected devices and skin monitoring apps: can help objectively track changes in skin condition or routine; have limited medical value and do not replace a clinical examination.
- Fractional lasers, LED, radiofrequency, and focused ultrasound: medical or cosmetic procedures with specific indications, to be performed by a trained professional.
- Microbiome-based cosmetics: prebiotics, postbiotics, fermented products; emerging avenues currently under study.
- In-store hair and skin diagnostics: non-invasive tests that can support the guidance provided by pharmacists.
What are the consequences of a damaged epidermis?
A compromised skin barrier can lead to several consequences:
- Increased sensitivity to cosmetics, fragrances, and allergens.
- Increased transepidermal water loss, dehydration, and a dull complexion.
- More frequent skin inflammation and recurrent micro-lesions.
- Opportunistic secondary infections (bacterial, fungal).
- Accelerated skin aging due to oxidative stress and chronic inflammation.
- Post-inflammatory hyperpigmentation (pronounced in skin types IV through VI).
Supporting the skin barrier requires skincare products enriched with ceramides, essential fatty acids, niacinamide, panthenol B5, and glycerin, along with gentle daily care.
How does the climate affect the epidermis?
Environmental conditions have a significant impact on the skin:
- Winter, cold, wind: dry ambient air, indoor heating, increased water loss. Adapt by using richer textures, balms, and occlusive skincare products.
- Summer, heat, humidity: often increased sebum production, maximum UV exposure. Opt for lightweight, non-comedogenic formulas and sun protection.
- Dry or high-altitude climates: Step up hydration; choose humectants and emollients.
- Urban pollution: Incorporate topical antioxidants and a thorough cleansing routine in the evening.
- Travel: Adapt your routine to the climate of your destination.
What is the ideal frequency for exfoliating the skin?
Exfoliation supports superficial skin renewal but should be done in moderation:
- Sensitive or reactiveskin: very gentle exfoliation no more than once a week, or take a break depending on the time of year.
- Normal to combination skin: 1 to 2 times a week.
- Oily skin: Twice a week, ideally with a BHA (salicylic acid), which penetrates sebum more effectively.
- Mature skin: Gentle chemical exfoliation is preferable to mechanical exfoliation, particularly with low-concentration AHAs.
AHAs and BHAs are photosensitizing: sunscreen is essential for the following days. In cosmetics, salicylic acid is limited to a maximum of 2% according to Regulation (EC) No. 1223/2009 (depending on the intended use). If irritation occurs, stop exfoliating and use soothing skincare products for a few days.
What is sun protection, and why is it so important?
Photoprotection aims to limit the effects of UV radiation on the skin. UVB rays are primarily responsible for sunburn and skin cancers (carcinomas, melanoma); UVA rays penetrate more deeply and accelerate skin aging (photoaging). The WHO and dermatology professional societies recommend:
- Daily topical sun protection (SPF 30 to 50 depending on the situation), even on cloudy days and when indoors (behind glass) to protect against UVA rays.
- Reapply every 2 hours during prolonged exposure and after swimming or sweating.
- Covering clothing, a wide-brimmed hat, and UV-blocking sunglasses.
- Avoid sun exposure between noon and 4 p.m. during peak risk periods.
- No prolonged exposure for young children; no exposure at all for infants under 6 months of age, according to current recommendations.
Dermatological monitoring of moles is recommended for those at high risk (fair skin type, personal or family history, past intense exposure).
How do cosmetics affect the skin?
Cosmetics are useful tools for skin care, provided they are suited to the individual’s skin type:
- Choose formulations that have been dermatologically tested, especially for sensitive skin.
- Test a new product on the inner elbow 24 to 48 hours before regular use.
- Choose active ingredients based on skin type (humectants for dry skin, BHA for oily skin, niacinamide for redness, etc.).
- Regarding parabens: European authorities have restricted and banned certain parabens (propylparaben and butylparaben in certain applications), while short-chain parabens (methyl- and ethylparaben) remain authorized under Regulation (EC) No. 1223/2009; their use depends on current assessments.
- Regarding sulfated surfactants (SLS, SLES): they can be drying for sensitive skin; choose based on tolerance.
- To diagnose a reaction (irritation, contact allergy, photoallergy), a dermatologist may recommend an appropriate evaluation (including patch tests).
