Compatibility of L-Ascorbic Acid (Vitamin C) and Niacinamide (Vitamin B3)

In skincare formulations, L-Ascorbic Acid (Vitamin C) and Niacinamide (Vitamin B3) are generally not recommended to be mixed in the same product, especially at high concentrations or specific pH levels.

The primary reasons are:

1. pH Sensitivity: L-Ascorbic Acid is most stable and effective at a low pH (typically below 3.5). Niacinamide, on the other hand, is more stable at a neutral pH (around 5-7).
2. Interaction and Degradation: When mixed at a low pH suitable for L-Ascorbic Acid, Niacinamide can hydrolyze into Niacin (Nicotinic Acid). This conversion can lead to a decrease in the efficacy of both ingredients and, more importantly, Niacin is known to cause skin flushing, redness, and irritation. Conversely, formulating at a higher pH suitable for Niacinamide can destabilize L-Ascorbic Acid, causing it to oxidize and lose its potency.

While some modern formulations use specific technologies or derivatives to mitigate this issue, the general rule is to avoid combining L-Ascorbic Acid and Niacinamide in the same formula to ensure stability, efficacy, and minimize the risk of skin irritation.