You will find both lactic acid and niacinamide on the ingredient lists of many well-formulated products, but rarely explained together. This piece covers what each one does, why they work better in combination than either does alone, and what the old argument against pairing them was actually based on.
What lactic acid does in the skin
Lactic acid is an alpha-hydroxy acid, which means it works by dissolving the bonds between dead skin cells at the surface, allowing them to shed cleanly rather than accumulating and causing dullness, uneven texture and congestion. It is derived from milk or fermentation and has a larger molecular size than glycolic acid, making it meaningfully gentler while remaining highly effective.
What distinguishes lactic acid from most other AHAs is its secondary function. It is a natural moisturising factor, a category of compound that the skin uses to attract and retain water within its own structure. So while it is resurfacing the skin surface, it is simultaneously hydrating it. This dual action makes lactic acid particularly well suited to mature, dry or dehydrated skin types that might find glycolic acid too stimulating.2
What niacinamide does in the skin
Niacinamide is Vitamin B3, and it is one of the most clinically well-supported ingredients in cosmetic skincare. It strengthens the skin's barrier function by increasing the production of ceramides and other lipids that hold the outer layers of the skin together. It also reduces redness and blotchiness, and inhibits the transfer of melanin to surface skin cells, which over time evens out hyperpigmentation and the general unevenness of tone that comes with sun exposure and ageing. At 4%, niacinamide has been shown in clinical trials to significantly reduce yellowing, wrinkling, red blotchiness and hyperpigmented spots in ageing facial skin.1
Why the combination is better than either alone
Used together, lactic acid and niacinamide address the limitations each one has individually. Lactic acid resurfaces, renews and hydrates, but at high concentrations it can cause transient redness or irritation in sensitive or reactive skin types. Niacinamide's anti-inflammatory action directly counteracts this. In a product that contains both, the niacinamide functions as a built-in buffer, making a high-strength lactic acid formula significantly more tolerable without reducing its exfoliating efficacy.
The combination also addresses the skin more comprehensively. Lactic acid improves texture and stimulates cell turnover. Niacinamide evens tone, supports the barrier and reduces redness. The two sets of benefits are complementary rather than overlapping.3
The myth about lactic acid and niacinamide reacting
For several years, a concern circulated in skincare communities that AHAs and niacinamide should not be used together. The argument was that the combination could produce niacin through a chemical reaction, potentially causing flushing. Subsequent research has clarified the situation. While the reaction in question can theoretically occur, it requires specific conditions of prolonged heat exposure that simply do not apply to cosmetic products stored and used at room temperature. Dermatologists and cosmetic chemists now consistently support the combination.3,4
The OSKIA Liquid Mask: formulated with both
The OSKIA Liquid Mask Lactic Acid Micro-Peel is built around the lactic acid and niacinamide combination. It contains 10% lactic acid, the EU maximum for a leave-on cosmetic, alongside Niacinamide, mixed molecular weight Hyaluronic Acid, MSM and Pro-Vitamin B5. The niacinamide in this formula is specifically there to make the 10% lactic acid concentration tolerable for regular use, including for skin types that have previously struggled with high-strength exfoliating acids.
Frequently asked questions
Can lactic acid and niacinamide be used on sensitive skin?
Yes, and this combination is one of the better options for sensitive skin specifically. Niacinamide's anti-inflammatory and barrier-strengthening properties reduce the likelihood of the transient redness that lactic acid can cause.
Does niacinamide cancel out the effect of lactic acid?
No. Niacinamide does not neutralise or reduce the exfoliating action of lactic acid. The two work on different mechanisms entirely. Niacinamide reduces inflammation and supports the barrier; lactic acid dissolves bonds between dead skin cells. The combination produces both sets of benefits simultaneously.
Is lactic acid with niacinamide suitable for hyperpigmentation?
It is, and the combination is particularly well suited to this concern. Lactic acid accelerates the shedding of pigmented surface cells. Niacinamide inhibits the transfer of melanin to skin cells. Used consistently, the combination works on both the pigment that is already visible and the processes that create new pigmentation.
1. Bissett DL, et al. "Topical niacinamide reduces yellowing, wrinkling, red blotchiness and hyperpigmented spots in aging facial skin." Int J Cosmet Sci, 2004.
2. Smith WP. "Epidermal and dermal effects of topical lactic acid." J Am Acad Dermatol, 1996.
3. Gehring W. "Nicotinic acid/niacinamide and the skin." J Cosmet Dermatol, 2004.
4. Levin J, Momin SB. "How much do we really know about our favorite cosmeceutical ingredients?" J Clin Aesthet Dermatol, 2010.
