If you want to discuss whether glycolic acid and niacinamide can be used together in "ordinary" (brand) products, you should carefully examine the nature of the two. Glycolic acid belongs to the fruit acid category, which has the ability to exfoliate and promote skin metabolism, and can rejuvenate the skin. Niacinamide can inhibit melanin transport, improve skin luster, and have the effect of stabilizing the skin.

In theory, the two seem to be contradictory. Glycolic acid makes the stratum corneum of the skin thin, and the skin may be sensitive, while niacinamide is also at risk of sensitization under high concentrations or specific skin types. However, the "ordinary" formula has been carefully developed. The concentration of glycolic acid and nicotinamide in its products has been considered. Moderate concentration combination can promote strengths and avoid weaknesses.

Use the combination of these two products and try it on a small scale first. See if the skin is uncomfortable, such as redness, itching, tingling, etc. If there is no adverse reaction, gradually increase the area and frequency of use. And when using, pay attention to skin moisturization and sun protection. Glycolic acid makes the skin more sensitive to ultraviolet rays, sun protection is omitted, and it is easy to cause skin damage.

In short, glycolic acid and nicotinamide are in "ordinary" products, after a reasonable formula, or compatible. However, individual skin types are different, so be careful before use to ensure skin health.