Understand the Structure of the Skin and Its Relationship with Cosmetics

The skin is the largest organ of the human body and plays a vital role in protection, regulation, and sensory perception. To understand how cosmetic ingredients work, it is essential to know the layers of the skin: epidermis, dermis, and hypodermis. In this article, we explain their structure, functions, and how they interact with cosmetic products.

Why Is It Important to Understand the Layers of the Skin in Cosmetics?

When developing and applying cosmetic products, understanding the anatomy of the skin helps in selecting the most effective ingredients. Each layer has specific characteristics that determine the penetration, absorption, and efficacy of cosmetic actives.

Epidermis: The Protective Barrier

The epidermis is the outermost layer of the skin. It acts as a barrier against external aggressors such as bacteria, UV radiation, and pollutants. It consists of several sublayers, including:
  • Stratum corneum: where dead cells accumulate; it is key for protection.
  • Basal layer: where new cells are generated and melanin is produced.

Main Functions of the Epidermis:

  • Protection from the environment
  • Prevention of water loss
  • Production of keratin and melanin

Cosmetic Ingredients That Act on the Epidermis:

  • Moisturizers (high molecular weight hyaluronic acid)
  • Gentle exfoliants (AHAs, BHAs)
  • Sunscreens

Dermis: The Middle Layer That Provides Firmness

The dermis lies beneath the epidermis and is where the skin’s support structure is found. It contains collagen, elastin, blood vessels, and nerve endings.

Main Functions of the Dermis:

  • Structural support and elasticity
  • Thermal regulation
  • Nutrient supply to the epidermis

Cosmetic Ingredients That Act on the Dermis:

  • Peptides
  • Retinoids
  • Low molecular weight hyaluronic acid
  • Growth factors

These ingredients require formulations that can penetrate beyond the epidermis to stimulate collagen production and improve firmness.

Hypodermis: The Deepest Layer

The hypodermis, or subcutaneous tissue, is composed mainly of fat and connective tissue. Its role is to protect internal organs, act as an energy reserve, and assist in thermal insulation.

Main Functions of the Hypodermis:

  • Mechanical protection
  • Energy storage (fat)
  • Temperature regulation

Although most cosmetic products do not directly reach this layer, advanced aesthetic treatments (such as mesotherapy or device-based therapies) can have an impact on the hypodermis.

How to Choose Cosmetic Ingredients According to Skin Layers

When formulating a cosmetic product, it is crucial to consider which skin layer it is intended to target. For example:
  • To hydrate the surface: use large molecular size ingredients (like glycerin or panthenol).
  • To treat wrinkles and firmness loss: use smaller molecules like retinol or peptides, which can reach the dermis.

Conclusion

Understanding the layers of the skin — epidermis, dermis, and hypodermis — is essential to grasp how cosmetic products work and to select the most appropriate active ingredients. At Lemmel, we provide high-quality cosmetic raw materials, designed to act effectively and safely at every level of the skin.