Understanding Ingredient Concentration When Layering Products

When you apply multiple skincare products containing the same active ingredient, like GlucoBright™ (Acetyl Glucosamine), the concentration of the ingredient on your skin doesn't simply add up in a linear fashion.

Each product is formulated with a specific concentration of the active ingredient (in your example, 4% GlucoBright™). When you apply the toner, your skin is exposed to a 4% concentration from that product. When you apply the cream on top, your skin is then exposed to a 4% concentration from the cream layer as well.

Think of it as applying multiple layers of paint with the same color intensity. The total amount of paint on the wall increases, but the intensity of the color within each layer of paint remains the same. Similarly, applying a second product with 4% GlucoBright™ doesn't create an 8% concentration on the skin's surface or within the skin layers.

The skin absorbs ingredients based on the concentration present in the product it is in contact with, as well as the product's formulation and your skin's condition. While layering increases the total amount of the ingredient applied, the skin is primarily interacting with the concentration within each product layer.

Therefore, using a toner with 4% GlucoBright™ followed by a cream with 4% GlucoBright™ means you are applying two products, each formulated at a 4% concentration. This does not mean your skin is suddenly exposed to an 8% concentration. As long as each individual product is formulated within the recommended usage rate (for GlucoBright™, the recommended range is 1-8%, so 4% is well within this limit), layering them in this manner is generally acceptable and does not typically lead to exceeding the effective or safe concentration limit on the skin.

This aligns with the previous reply you received; you are essentially applying the same concentration again, not doubling the concentration itself.