Mel Sahyoun Hyaluronic Acid Serum: When it comes to finding the best hydrating serum, Mel Sahyoun's Hyaluronic Acid Serum is a standout choice. This product is specifically formulated to provide intense hydration to the skin. Hyaluronic acid is a powerful humectant that can retain up to 1,000 times its weight in water, making it an excellent choice for locking in moisture.