Does pH matter when layering skincare products?

Yes, pH is relevant for certain actives. Vitamin C (L-ascorbic acid) requires a low pH below 3.5 to be effective, and AHAs/BHAs work best at pH 3–4. Applying these after a high-pH toner or essence can reduce their efficacy. Wait one to two minutes between applying a low-pH active and a higher-pH product to allow the skin's pH to stabilize. For most moisturizers and serums at neutral pH, order by texture is sufficient.