Can I use this in my routine along with Niacinamide?

Yes, of course! The form of Vitamin C we use in El Dorado is Tetrahexyldecyl Ascorbate (THDA), which is a very shelf-stable, oil-soluble form of Vitamin C. It is a different form than L-Ascorbic Acid (L-AA), which is the one that may cause flushing when combined with Niacinamide.