Compatibility of Azelaic Acid (Liquid Azelaic™) and Zinc PCA

Based on the information indicating that Azelaic Acid (Liquid Azelaic™) and Zinc PCA cannot be used together, this typically means they should not be included in the same cosmetic formulation. There might be chemical incompatibilities that affect the stability, efficacy, or safety when combined in a single product.

However, if they are in separate products, you can generally apply them to your skin at the same time (or one after the other) without issue. This allows you to benefit from both ingredients' properties without the formulation challenges of mixing them directly.