Unlocking the Science of Serums

By Dr Juanri Jonck, Aesthetic Doctor and Founder, LifeLAB Medical, Pretoria

In my Pretoria practice, one of the most common questions I hear is, “Doctor, with so many products out there, what truly makes a difference?” More often than not, the conversation leads to one product category that consistently delivers results when used correctly: the serum.

From a medical and aesthetic perspective, this is not about trends. It is about understanding how skin functions, how it absorbs ingredients, and how we work with its biology rather than against it.

Why serums work differently

The effectiveness of a serum depends on its structure and formulation. Serums are designed as low-viscosity products with a high concentration of active ingredients.

These actives often include vitamin C, retinol and niacinamide. Unlike richer creams, serums contain fewer emollients and fillers used to create thickness and slip.

The skin’s outer layer, the stratum corneum, functions as a protective barrier. Rich creams mainly sit on the surface, hydrating and sealing in moisture. This is important for comfort and preventing water loss, but it limits how deeply corrective ingredients penetrate.

A well-formulated serum is built to move more efficiently through this barrier. Its lightweight structure and carefully selected delivery systems allow smaller active molecules to reach deeper layers of the skin. This is where cellular repair, collagen stimulation and pigment regulation take place. In simple terms, creams manage the surface. Serums drive change below it.

Supporting skin instead of creating dependency

A concept I often explain to patients is what I call “lazy skin”. Skin is designed to renew itself. It produces new cells, lipids and collagen as part of its natural function. When we rely too heavily on thick, occlusive products to do all the work, we can slow these internal processes. The skin becomes comfortable, but not corrected.

Targeted serums work differently. Used consistently, they support the skin’s natural activity instead of replacing it.

Antioxidants such as vitamin C and vitamin E reduce daily free radical damage, so the skin does not stay in a constant state of repair.
Niacinamide supports the skin’s own production of ceramides, strengthening the barrier from within.
Retinol communicates directly with skin cells, encouraging healthier cell turnover and collagen production over time.

The goal is not to overwhelm the skin, but to guide it. When used correctly, serums help the skin function better on its own, leading to long-term improvement rather than short-term relief.

How to apply serums for best results

Correct application matters as much as ingredient choice. Order is key.

Cleanser
This prepares the skin and removes barriers to absorption.

Serum
Apply to clean, slightly damp skin. This is your primary treatment step.

Moisturiser or barrier cream
This seals in the serum and supports the skin barrier, especially during the adjustment phase when introducing active ingredients.

Sunscreen in the morning
This step is essential. No active ingredient can counteract ongoing sun damage.

When choosing a serum, focus on ingredients with strong clinical evidence.

Vitamin C supports collagen production, brightens skin tone and provides antioxidant protection.
Retinol remains the gold standard for addressing ageing and uneven texture.
Niacinamide improves barrier strength, reduces inflammation and helps regulate oil production.
Alpha-lipoic acid provides broad antioxidant support and may improve skin texture and pore appearance.

There is no universal solution. The right serum depends on your skin type, age, concerns and environment. Skin in Pretoria’s climate behaves differently from skin in coastal or colder regions. What benefits dry, mature skin may overwhelm oily or acne-prone skin.

The role of professional guidance

This is where clinical guidance becomes important. Medical-grade serums differ from retail products in potency, precision and professional oversight.

In a medical setting, we work with pharmaceutical-grade actives at evidence-based concentrations. These formulas are stabilised for performance, not shelf appeal. We also tailor recommendations for specific concerns such as pigmentation, rosacea or acne.

Most importantly, you gain a professional partner. We assess your skin, review your history, and guide you through a safe introduction and the correct combinations. This ensures results while reducing the risk of irritation or setbacks.

A practical prescription for results

If you want to invest in a serum and see meaningful improvement, keep the approach simple.

Choose one targeted, medical-grade serum with professional guidance.
Use it consistently.
Introduce active ingredients gradually, especially retinoids.
Commit to at least three months to allow for a full skin renewal cycle.

Above all, never skip daily broad-spectrum sunscreen. This step is non-negotiable. Without sun protection, even the best serum will fail.

Commit to the science, and you commit to lasting skin health.

Dr Juanri Jonck is the founder and lead aesthetic doctor at LifeLAB Medical in Pretoria, where she combines medical expertise with a holistic approach to skin health.