Yes, you can apply niacinamide to damp skin. Niacinamide is a water-soluble vitamin B3 derivative that can be used as a topical skin care ingredient. It is a non-irritating, anti-inflammatory ingredient that can help even out skin tone and reduce the appearance of wrinkles and fine lines. Applying it to damp skin helps to keep the skin moisturized and to ensure that the niacinamide is absorbed deeply into the skin.