By Dr. Daniel Pehböck, Reading time approx. 8 minutes
As a doctor, I observe daily how many people treat their skin with well-intentioned but often ineffective or even harmful products. The skincare industry promises miracles, but only medically sound skincare can sustainably improve skin health. In this article, you will learn which ingredients work evidence-based, how to properly analyze your skin, and which mistakes you should definitely avoid.
Table of Contents
The Skin Barrier – Foundation of Skin Health
The skin barrier, medically known as the stratum corneum, is the outermost layer of our skin and acts as a shield against external influences. It consists of corneocytes (horny skin cells) embedded in a lipid matrix – comparable to bricks in mortar. This structure prevents water loss (TEWL – transepidermal water loss) and protects against the penetration of pollutants, allergens, and microorganisms.
An intact skin barrier has a pH value of 4.5 to 5.5 – the so-called acid mantle. This acidic pH is essential for the activity of important enzymes (proteases and lipases) involved in the breakdown of corneodesmosomes and thus regulate the desquamation of the skin. Many conventional soaps and cleansing products with an alkaline pH (pH 8-10) destroy this protection sustainably.
💡 Medical Tip: A disturbed skin barrier is manifested by dryness, redness, feelings of tightness, and increased sensitivity. In the presence of these symptoms, care should be shifted to barrier-strengthening products with ceramides, cholesterol, and free fatty acids in the physiological ratio 3:1:1.
Components of the Skin Barrier
| Component | Function | Important Ingredients |
|---|---|---|
| Ceramides | Lipid structure, water binding | Ceramide 1, 3, 6-II |
| Natural Moisturizing Factor (NMF) | Moisture binding | Urea, amino acids, PCA |
| Free Fatty Acids | Lipid barrier, pH regulation | Linoleic acid, palmitic acid |
| Cholesterol | Lipid matrix stability | Cholesterol |
Determine Skin Types Correctly
Correct determination of skin type is the basis of any effective skincare. Many people misjudge their skin type and thus use unsuitable products. In dermatological practice, we primarily distinguish between four skin types, classified according to sebum production and moisture content.
The Four Main Skin Types
Normal Skin: Balanced sebum production, fine pores, no redness or blemishes. The ideal state, which occurs in only about 20% of the population. The T-zone (forehead, nose, chin) shows no excessive shine.
Dry Skin: Reduced sebum production, disturbed skin barrier, increased TEWL. Manifested by flaking, tightness, and fine dryness lines. Can be genetically determined or caused by external factors (climate, improper care).
Oily Skin: Overactive sebaceous glands, enlarged pores, shine on the entire face. Prone to comedones and acne. Often hormonally influenced (androgens stimulate sebum production).
Combination Skin: Combines oily T-zone with normal to dry cheeks. The most common skin type, requiring differentiated care for different facial areas.
⚠️ Important: Sensitive or reactive skin is not a skin type but a skin condition that can occur in any skin type. Characteristic are redness, burning, and overreactions to skincare products. Products without fragrances, essential oils, and harsh preservatives should be used here.
Evidence-Based Ingredients in Skincare
Medical skincare is based on scientifically proven ingredients with documented efficacy. Unlike cosmetic products with marketing promises, dermatological preparations should be based on clinical studies and pharmacological findings.
Retinoids – The Gold Standard of Anti-Aging Care
Retinoids (Vitamin A derivatives) are the most researched anti-aging agents with over 700 scientific publications. They bind to nuclear retinoid receptors and affect gene expression. Clinically proven effects include:
- Increase in collagen-I synthesis by up to 80%
- Reduction of matrix metalloproteinases (collagen-degrading enzymes)
- Normalization of cell differentiation
- Improvement of the epidermal barrier
- Reduction of hyperpigmentation
In practice, we distinguish between prescription tretinoin (0.025–0.1%), adapalene (0.1–0.3%), and over-the-counter retinol (0.3–1%). Conversion of retinol to tretinoin requires several enzymatic steps, which is why retinol is gentler but also weaker in effect.
Vitamin C – Antioxidant and Collagen Booster
L-ascorbic acid is an essential cofactor of prolyl and lysyl hydroxylases, enzymes indispensable for collagen synthesis. Additionally, vitamin C neutralizes reactive oxygen species (ROS) and protects against UV-induced photoaging. The optimal concentration is 10–20% in a pH-stabilized formulation (pH 2.0–3.5).
| Ingredient | Main Effect | Concentration | Evidence Level |
|---|---|---|---|
| Tretinoin | Collagen synthesis, cell regulation | 0.025–0.1% | Very high (1a) |
| Niacinamide | Barrier strengthening, sebum reduction | 2–5% | High (1b) |
| Hyaluronic Acid | Moisture binding | 0.1–2% | High (1b) |
| Azelaic Acid | Depigmenting, antibacterial | 15–20% | High (1b) |
| Peptides | Signal molecules, collagen stimulation | 2–10% | Moderate (2a) |
Niacinamide – The Multi-Functional Ingredient
Niacinamide (Vitamin B3) shows multiple positive effects at concentrations of 2–5%: strengthening the skin barrier by stimulating ceramide synthesis, reducing transepidermal water loss by up to 24%, decreasing sebum production in oily skin, and brightening hyperpigmentation by inhibiting melanin transfer. The excellent tolerance makes niacinamide ideal for sensitive skin.
The Optimal Care Routine
An evidence-based skincare routine follows a structured build-up, where the products are applied in the right order and consistency. The principle is: from thin to thick, from water-based to oil-based formulations.
Morning Routine
- Cleansing: Mild syndet cleansing with pH 5.5 or micellar water
- Toner/Essence: Optional, for pH stabilization and preparation
- Antioxidant Serum: Vitamin C 10–20% in the morning for UV protection
- Eye Care: Special formulation for periorbital region
- Moisturizer: Skin-type adapted with ceramides/hyaluronic acid
- Sunscreen: SPF 30–50, UVA+UVB, at least 2 mg/cm² (approx. 1/4 teaspoon for the face)
Evening Routine
- Double Cleansing: First oil-based (makeup/sunscreen), then water-based
- Exfoliation: 2-3x/week chemical peel (AHA/BHA 5–10%)
- Treatment Serum: Retinoid, niacinamide or specific active ingredients
- Eye Care: Retinol-free formulation for the eye area
- Night Cream: Richer than day cream, repair-focused
- Occlusive Care: Optional for very dry skin (petrolatum, squalane)
💡 Pro Tip: Introduce new active ingredients individually and gradually. Start with 2-3x weekly application and slowly increase. The so-called "retinoid dermatitis" (redness, flaking, irritation) is usually dose-dependent and can be minimized by slow acclimatization.
Avoid Common Mistakes
In my practice, I regularly see the same care mistakes that impair skin health and can even cause dermatological problems. These mistakes are often based on misinformation from advertising and social media.
Too Aggressive Cleansing
Excessive cleansing with alkaline soaps, scrubs, or drying products destroys the skin barrier and paradoxically leads to increased sebum production (reactive seborrhea). The skin tries to compensate for the lipid loss. The popular "squeaky clean" feeling is also counterproductive – it signals a damaged barrier.
Too Many Active Ingredients at Once
Combining multiple active ingredients without medical understanding often leads to irritation. Particularly problematic: Retinol + high-concentration AHA/BHA, Vitamin C + niacinamide in unstable formulations, or multiple acids at once. A minimalist routine with a few, but effective active ingredients is usually more successful.
Neglecting Sunscreen
UV radiation is the main factor for premature skin aging (photoaging), responsible for up to 80% of visible signs of aging. UVA rays penetrate deep into the dermis and destroy collagen and elastic fibers through ROS formation. Without consistent UV protection, all anti-aging measures are ineffective.
⚠️ Critical Skincare Mistakes:
- Washing too often (more than 2x daily)
- Using products with denatured alcohol on dry skin
- Mechanical scrubs with inflammatory acne
- Skipping moisturizer for oily skin
- Immediate discontinuation with initial retinoid irritation
Targeted Treatment of Special Skin Issues
Acne and Blemished Skin
The pathogenesis of acne comprises four main factors: follicular hyperkeratosis, increased sebum production, colonization with Cutibacterium acnes, and inflammatory processes. Topical therapy addresses these points:
- Retinoids (Adapalene 0.1%): Normalization of keratinization, anti-inflammatory
- Benzoyl Peroxide 2.5–5%: Antibacterial against C. acnes, keratolytic
- Salicylic Acid 0.5–2%: Lipophilic, penetrates pores, keratolytic
- Niacinamide 4%: Sebum reduction, anti-inflammatory
- Azelaic Acid 15–20%: Antibacterial, depigmenting in post-inflammatory hyperpigmentation
Rosacea
Rosacea is a chronic inflammatory dermatosis with neurovascular dysregulation. Skincare should be gentle, barrier-strengthening, and anti-inflammatory. To be avoided: alcohol, fragrances, essential oils, menthol, harsh surfactants, AHA/BHA in high concentrations. Recommended are: Azelaic acid 15%, niacinamide 4%, green tea extract (EGCG), Centella asiatica, mineral UV protection.
Hyperpigmentation
Melasma and post-inflammatory hyperpigmentation require a multifaceted strategy: inhibition of tyrosinase (hydroquinone 2–4%, kojic acid, arbutin), acceleration of cell turnover (retinoids, AHA), inhibition of melanin transfer (niacinamide), and strict UV protection. Treatment requires patience – first results after 8–12 weeks.
Practical Tips from Medicine
Tip 1: The Sandwich Method with Retinoids
For retinoid beginners or those with sensitive skin: First apply moisturizer, wait 20 minutes, then the retinoid, followed by another thin layer of cream. This method buffers the effect, reduces irritation, and allows gentle acclimatization.
Tip 2: The Right Amount Makes the Difference
Too much product burdens the skin and causes blemishes. Rule of thumb: Serum = pea size, face cream = hazelnut size, sunscreen = 1/4 teaspoon. For serums with highly active ingredients (retinol, vitamin C) often 2-3 drops are enough.
Tip 3: Avoid Perioral Dermatitis
Leave a 1 cm wide area around the mouth, nose, and eyes when using active ingredients (especially retinoids). These areas have thinner skin and are prone to irritation. Use special eye creams for the eye area.
Tip 4: Hydration Inside and Out
Dehydrated skin is not the same as dry (lipid-poor) skin. Hyaluronic acid serums only work with sufficient humidity (>50%) or when an occlusive cream is applied afterwards. In a dry environment, hyaluronic acid can even draw moisture from the skin.
Conclusion and Recommendations
Medically based skincare relies on evidence-based ingredients, an intact skin barrier, and knowledge of one's own skin needs. The key insights summarized:
- The skin barrier is the foundation – Ceramides, cholesterol, and free fatty acids in the 3:1:1 ratio are essential
- Retinoids and vitamin C have the highest evidence level for anti-aging effects
- UV protection is the most important anti-aging measure (SPF 30-50 daily)
- Less is more – a minimalist routine with effective ingredients surpasses complex multi-product systems
- Patience is required – visible results appear after 8-12 weeks of consistent use
- For persistent skin issues, dermatological investigation is essential
Investing in high-quality, medically tested skincare products and professional advice pays off in the long term through healthier, more resilient skin. Start with the basics: gentle cleansing, effective moisturizing, consistent sun protection – and supplement selectively with evidence-based ingredients for your specific needs.
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