Retinol: What to combine it with?

The combination of retinol with niacinamide is particularly beneficial forimproving skin tolerance while optimising the firming effects of retinol. Indeed, by stimulating the synthesis of ceramides and essential proteins for the cohesion of the stratum corneum, such as filaggrin, niacinamide provides structural support to the skin and helps reduce water loss and discomfort often associated with the first weeks of retinol use. Beyond this barrier action, niacinamide also acts as an anti-inflammatory by limiting the production of certain cytokines (IL-1β, IL-6, TNF-α) and reducing the expression of COX-2. It also has an antioxidant and depigmenting effect, complementary to that exerted by retinol.

A recent study has examined the skin benefits provided by a moisturising cream containing 0.5% retinol, 4.4% niacinamide, 1% resveratrol, and 1.1% hexylresorcinol. 25 participants, with an average age of 53, applied this product for ten weeks, followed by a sunscreen with an SPF of 30. From the fourth week of use, an improvement in wrinkle scores, skin smoothness, and complexion uniformity was observed. However, it is difficult to draw solid conclusions as no control was carried out and the observed effects could be partly due to the incorporation of a sunscreen into the skincare routine.

Niacinamide is a beneficial ingredient that enhances the effectiveness of retinol while mitigating its irritating effects.

Alpha-hydroxy acids (AHA) are organic compounds with recognised keratolytic properties. They help to exfoliate the skin's surface and brighten dull complexions. The main AHAs present in the skincare market are glycolic acid and lactic acid. When combined with retinoic acid, the active form of vitamin A, glycolic acid has shown increased effectiveness in reducing blemishes and acne scars.

Indeed, a retrospective study conducted with 35 patients who had suffered from acne and had scars evaluated the effectiveness of a treatment combining 0.025% retinoic acid and 12% glycolic acid. After daily application for twelve weeks, 91.4% of participants showed an improvement in their acne scars and, among them, 85.71% saw a significant reduction in their post-inflammatory hyperpigmentation.

Products containing retinol and glycolic acid may be beneficial for reducing scars or blemishes, but this combination is strongly discouraged for sensitive skin.

Combining retinol with vitamin C allows us to target multiple aspects of skin ageing: loss of firmness, cellular oxidation, dull complexion, and pigment irregularities. These two active ingredients have a complementary action. Retinol stimulates the synthesis of type I and III collagen, while vitamin C enhances this action by promoting the activity of prolyl-hydroxylase, an enzyme essential for the stabilisation of collagen fibres. Therefore, these two molecules contribute to firming the skin and reducing the depth of wrinkles.

The combination of vitamin C and retinol is also relevant for combating blemishes, as demonstrated by a study by NATAKANKITKUL and his team. These researchers wanted to compare the effectiveness of a 0.2% retinol formulation, another containing 5% sodium ascorbyl phosphate, a derivative of the vitamin C, and a third containing both actives. This study gathered 45 participants suffering from acne. They were divided into three groups of fifteen people and applied one of the formulations daily for eight weeks. Significant reductions in the number of acne lesions were recorded, particularly among individuals who received the product with retinol and sodium ascorbyl phosphate.

The combination of retinol and peptides is currently emerging as one of the most promising in skincare. It's worth noting that peptides do not refer to a specific active ingredient but a family of molecules. More precisely, peptides are polymers of amino acids linked together by peptide bonds. There is a wide variety of them, such as signal peptides (example: palmitoyl pentapeptide-4), which stimulate the production of collagen and elastin, neurotransmitter inhibitor peptides (example: argireline), which reduce the contraction of facial muscles, mimicking the effect of botox, or even carrier peptides (example: copper-peptide GHK-Cu), which facilitate the penetration of certain trace elements. By combining retinol and peptides, it is therefore possible to act on several levels: reactivation of cellular activity, support of the extracellular matrix, and improved skin tolerance.

Several studies have focused on the synergy between retinol and certain peptides in recent years. A study conducted by GOLDBERG and his team evaluated a cream containing retinol, a tripeptide, and glaucine on 20 participants over three months. The results showed a significant improvement in skin texture, an increase in levels of type I and III collagen, and a reduction in signs of photoaging, without compromising the skin barrier. Another research, conducted by LEPHART and his team, tested a formulation based on retinol, pea peptide, and antioxidants on 30 subjects over an eight-week period. This study revealed an improvement in hydration, elasticity, and a decrease in transepidermal water loss. Again, no irritation was reported.

The combination of retinol with certain peptides not only enhances the effects of retinol on skin ageing but also improves its tolerance.

Often criticised, the combination of retinol and benzoyl peroxide could, in some cases, be beneficial. To recall, the benzoyl peroxide is an antibacterial, anti-inflammatory, sebostatic and keratolytic active ingredient used to treat acne. However, it is frequently associated with skin irritations, just like retinoids, and is only applied in the evening as it can cause photosensitisation of the skin. At first glance, combining these two actives could therefore risk drying out and weakening the epidermis.

Scientific studies have been conducted on a cream containing 4% benzoyl peroxide, retinoids (0.05% retinol and 0.5% retinyl palmitate), 1% mandelic acid, and glycyrrhetinic acid. Over twelve weeks, 20 patients suffering from mild acne applied this product once a day to their face. Not only was this treatment well tolerated, but an improvement in their acne was noted, with reductions in the number of comedones by 65%, papular lesions by 62%, and pustular lesions by 80%.

It appears that, when properly balanced, the combination of retinol and benzoyl peroxide provides an effective option for managing mild acne. However, as a precaution, it is still recommended to gradually introduce these active ingredients, for instance by alternating their application every other evening at the start.