Best Serum For Combination Skin: L'Oréal Paris Hyaluronic Acid Serum This popular L'Oreal Paris Hyaluronic Acid Serum ($24) keeps combination skin hydrated using 1.5% Pure Hyaluronic Acid. Plus, the formula is paraben- and fragrance-free. Image Source: amazon.com L'Oreal Paris Hyaluronic Acid Serum $24 from amazon.com Buy Now