Are moisturiser and serum interchangeable? We say nope!
Moisturiser and serums treat the skin differently. Serums are formulated to help keep the skin in good condition whereas moisturiser is for hydrating. Skin is made up of layers. The top oil-based layers are best conditioned by oils whereas an active moisturiser will help the water-based deeper layers retain moisture. For best results use both - pop moisturiser on twice daily then add a little concentrate oily serum every night.