Best moisturizer for neck Retinol: Smoothes fine line Collagen: Improves moisture-retaining. Collagen is a crucial component that supports skin elasticity and firmness. As we age, collagen levels in the skin decrease, leading to skin laxity and wrinkle formation. Hyaluronic acid 5%: Deeply moisturizing, Hyaluronic Acid is a potent hydrating agent that deeply moisturizes the skin, increasing its water content and giving it a plumper, smoother appearance.