Can combining Vitamin C and Niacinamide negate their respective effects?

It is common to read that vitamin C and niacinamide, although effective in themselves, are not compatible. Their combination would neutralise their effects. Similarly, it is suggested that the two compounds could potentially react to produce nicotinic acid, which can lead to skin reactions such as redness, itching, and temporary irritations. However, such a phenomenon occurred when pure vitamin C and niacinamide were formulated and maintained at high temperatures.

For enhanced chemical stability in topical formulations, most skincare products nowadays contain derivatives of Vitamin C, such as ascorbyl tetraisopalmitate, sodium ascorbyl phosphate, tetrahexyldecyl ascorbate, ascorbyl glucoside, etc.

However, given that they offer similar benefits and both target the same skin concerns, it would be logical that their combined use could, in a sense, enhance their effects. Indeed, scientists suggest combining them. Even though they provide the same advantages, niacinamide and vitamin C work in synergy through different biological mechanisms to exert their effects. They thus address skin issues from different angles and would therefore be complementary.

It would therefore seemingly be relevant to combine these two active ingredients to enhance their effects on the concerns they address, without any skin reactions and without impacting their efficacy. Indeed, studies have shown that it is possible to safely mix them, whether together in the same formulation or layered with the use of different products, particularly as a solution to photoaging and uneven skin pigmentation.

Indeed, such a combination of active ingredients in a topical formula would have a more significant effect on the reduction of melanogenesis than a single agent. Vitamin C results in a decrease in melanin synthesis by inhibiting tyrosinase, an enzyme necessary for its production, while niacinamide prevents the transfer of melanosomes from melanocytes to epidermal keratinocytes.

This blend of active ingredients has also demonstrated a reduction in the synthesis and content of melanin pigments in the skin by modulating the oxidative stress induced by UV radiation (antioxidant property), a primary mediator of the melanogenesis process, but also by inhibiting the degradation of collagen and elastin fibres by metalloproteinases.

Today, there are countless facial cleansers, toners, moisturisers, serums or eye contour treatments that contain both the vitamin C and the niacinamide in their formulas. You can also layer two independent treatments in the same skincare routine, that is, apply a niacinamide treatment followed by another with vitamin C, or vice versa.

Indeed, there is no specific order to follow when applying these two active ingredients to the skin. However, the way in which you layer niacinamide and vitamin C largely depends on the texture of the products. You should first apply the treatments with the most fluid and light texture, then move towards products with a thicker consistency as you layer. One key point is that the sunscreen should always be the final layer of care in the morning.

However, before starting to incorporate new products into your daily routine and layering treatments, there are certain points that must be kept in mind.

• Begin with one new product at a time and wait at least a week before wanting to add another product.

• Begin with an application once a day or every other day, depending on your skin type, to give the skin more time to adapt.

• When considering incorporating a new product, always conduct a skin test first by trying it in a small amount for at least 24 hours on a small area of the body (behind the ear, along the jawline, in the crook of the elbow or on the inner side of the wrist).

• Always ensure you are well acquainted with the manufacturer's instructions to understand how to best store and safely use them.

Even with niacinamide and vitamin C, which are known for their skin benefits, it is still possible that skincare products may not suit your skin.

• BYUN K. & al. A mixture of topical forms of polydeoxyribonucleotide, vitamin C, and niacinamide attenuated skin pigmentation and increased skin elasticity by modulating nuclear factor erythroid 2-like 2. Molecules (2022).

• BYUN K. & al. The combination of niacinamide, vitamin C, and PDRN mitigates melanogenesis by modulating nicotinamide nucleotide transhydrogenase. Molecules (2022).