What Skincare Ingredients Actually Do: The Complete Glossary

Niacinamide, retinol, AHAs, BHAs, ceramides, azelaic acid, bakuchiol, peptides... Cosmetic active ingredients have flooded skincare vocabulary. But between INCI names, abbreviations, and marketing promises, it's hard to know what really does what.

This glossary brings together the most important active ingredients, their actual mechanisms, and what you can concretely expect from them.

An active ingredient is only effective if you know why you are using it and how.

Hydrating Actives

Hyaluronic Acid (Hyaluronic Acid / Sodium Hyaluronate): A humectant that captures and retains water in the superficial layers of the skin. Its effectiveness depends on its molecular weight — high molecular weight for surface action, low molecular weight for deeper penetration. Apply to slightly damp skin and seal with a moisturizer.

Glycerin (Glycerin): A classic humectant, one of the most documented in cosmetology. It attracts water from the environment to the superficial layers of the epidermis. Well tolerated by all skin types, including acne-prone skin. Present in almost all moisturizing formulas.

Panthenol (Panthenol / Provitamin B5): A humectant and soothing agent. It converts into pantothenic acid in the skin and supports the repair of the skin barrier. Particularly useful for irritated skin, post-shaving, or during the retinization phase.

Ceramides (Ceramides): Structural lipids of the skin barrier. Along with free fatty acids and cholesterol, they form the "cement" between corneocytes. Their decrease with age or due to aggressive treatments weakens the barrier and increases transepidermal water loss. Ceramide-based formulas specifically restore this barrier.

Exfoliating Actives

AHAs — Alpha-hydroxy acids: Water-soluble chemical exfoliants that dissolve the bonds between dead cells on the skin's surface. The main ones are glycolic acid (the smallest, penetrates deepest) and lactic acid (milder, also hydrating). Effective on texture, radiance, and superficial spots. Caution: increase photosensitivity, mandatory sun protection.

BHA — Beta-hydroxy acid: Salicylic acid is the only BHA used in cosmetics. Oil-soluble, it penetrates the pores and dissolves sebum blockages. Keratolytic, comedolytic, and anti-inflammatory. A benchmark active ingredient for acne-prone skin and enlarged pores. Limited to 2% in cosmetics according to European regulations.

PHAs — Polyhydroxy acids (gluconolactone, lactobionic acid): Milder exfoliants than AHAs, with a larger molecule that penetrates less deeply. Better tolerated by sensitive and reactive skin. Also have a moisturizing effect.

Anti-aging Actives

Retinol (Retinol): A form of vitamin A that converts into retinoic acid in the skin. Stimulates cell renewal, collagen production, and regulates melanin. The most well-documented anti-aging active ingredient in cosmetics. Effective concentrations: 0.025% to start, up to 0.3% (European regulatory limit). Mandatory gradual introduction.

Retinal (Retinaldehyde): One step closer to retinoic acid than retinol in the conversion chain. More powerful at equal concentration, effective from 0.015%, better tolerated than tretinoin. A relevant alternative for progression without a prescription.

Bakuchiol: A plant-derived active ingredient (from Psoralea corylifolia seeds) often presented as "natural retinol." A randomized, double-blind trial published in the British Journal of Dermatology (Dhaliwal et al., 2019) showed comparable efficacy to 0.5% retinol in reducing wrinkles and pigmentation, with better tolerance. It does not act on the same receptors as retinol but produces similar effects. Compatible with pregnancy according to available data, unlike retinol.

Peptides: Short chains of amino acids that act as cellular messengers to stimulate the synthesis of collagen, elastin, or hyaluronic acid, depending on their sequence. The most documented are matrixyl (palmitoyl pentapeptide-4) and argireline (acetyl hexapeptide-3). Well tolerated, no photosensitization, suitable for mature or sensitive skin that cannot tolerate retinol.

Depigmenting Actives

Niacinamide (Vitamin B3): Inhibits melanin transfer to keratinocytes, regulates sebum, strengthens the barrier, and soothes inflammation. The ultimate versatile active ingredient. Effective from 4%, with effects on pigmentation between 5% and 10%. Well tolerated by all phototypes.

Azelaic Acid (Azelaic Acid): Inhibits tyrosinase (melanin synthesis enzyme) and has antibacterial and anti-inflammatory action. A benchmark depigmenting active for dark skin and during pregnancy. Well tolerated, with no risk of paradoxical hyperpigmentation.

Alpha-arbutin (Alpha-Arbutin): A stable and gradual tyrosinase inhibitor. Better tolerated and more stable than beta-arbutin. Suitable for maintenance or for skin that cannot tolerate acids.

Vitamin C (Ascorbic Acid): A powerful antioxidant that inhibits melanogenesis and protects collagen from oxidative stress. L-ascorbic acid is the most effective form but also the least stable (optimal pH 2.5-3.5, sensitive to oxidation). Derived forms (ascorbyl glucoside, sodium ascorbyl phosphate) are more stable and better tolerated on sensitive skin.

Soothing and Barrier-Repairing Actives

Allantoin (Allantoin): Soothing and mildly healing. Accelerates superficial cell renewal and reduces irritation. Present in many post-shaving treatments and products for sensitive skin.

Centella asiatica (Centella Asiatica Extract / Madecassoside): Plant extract with documented anti-inflammatory and healing properties. Stimulates collagen synthesis and strengthens the barrier. Popular in K-beauty, well scientifically validated for sensitive and reactive skin.

Zinc PCA: Locally regulates sebum production and has a mild anti-inflammatory action. Particularly suitable for oily, acne-prone skin.

The Paradermia Approach

Our pharmacist selects active ingredients based on your actual skin profile: precise indication, effective concentration, compatibility with other products in your routine. Knowing an active ingredient is not enough — knowing why it suits you and how to use it correctly is what determines the result.

Frequently Asked Questions

How do I know which active ingredients are in my Paradermia products?
Every product selected by our pharmacist is chosen based on its actual INCI list and the relevance of its active ingredients for the profiles it is recommended for. You don't buy a product with a trendy active ingredient on the label — you buy a product whose formulation has been verified.

Can all these active ingredients be used together?
No. Certain combinations cause problems and should be avoided or separated in time. Our pharmacist builds coherent protocols where each active ingredient has its place and frequency, without creating incompatibilities.