If you have yet to encounter the hydrate versus moisturize debate, you’re not alone. Even the most savvy skin-care consumers often consider the two interchangeable, but a hyaluronic acid serum and barrier-minded face moisturizer can deliver their own respective (and often complementary) benefits: In short, hydration offers water, while moisturizer imparts oil.
And that simple distinction means that they have two unique roles within skin, with implications for all skin types—and aging skin in particular. With that in mind, here’s why it’s worth discerning the key differences between hydration and moisturizing, and why you might benefit most from using both in your routine.
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What’s the difference between hydrating and moisturizing?
Think of hydration as filling the reservoir and moisturizing as building the dam, suggests Jessie Cheung, M.D., a board-certified dermatologist in Chicago, IL and New York, NY. “Hydrating is about increasing the water content within the skin and helping it attract and hold onto that water, largely through humectants and the skin’s own natural moisturizing factors,” she explains. “Moisturizing is about strengthening that outer barrier with lipids and helping prevent water from evaporating.”
Does aging skin need hydration, moisturization, or both?
Both components—water and lipids—are important for skin, but they become increasingly critical as you get older. Over time, “skin produces less of its own hyaluronic acid and natural moisturizing factors, so it doesn’t hold onto water as efficiently,” says Dr. Cheung. At the same time, she adds, our skin barrier weakens and produces fewer lipids like ceramides, which means water can escape more easily. “So aging skin isn’t just ’drier’,” she says. “It’s dealing with a double hit: less water retention capacity and a leakier barrier.”
This can lead skin to look and feel rough, dry, and crepey. But this isn’t the only change occurring in your skin as you age. “Collagen and elastin production also decline, and the skin’s ability to repair itself slows down,” says Jenna Queller, M.D., a board-certified dermatologist in Boca Raton, FL. “These changes can lead to increased dryness, rough texture, fine lines, and a loss of that youthful ‘bounce’ many people associate with well-hydrated skin.”
To complicate matters, hormonal shifts, like the swings and eventual drop in estrogen during perimenopause, can make the situation worse, since estrogen receptors play a role in the production of hyaluronic acid, barrier lipids, and even collagen. As a result, going with only hydration or moisture is a strategy that tends to “underperform” on mature skin, as Dr. Cheung puts it. “You need to replenish the reservoir and reinforce the dam,” she says.
Do you moisturize or hydrate first?
In general, hydration comes first. “I often recommend applying a hydrating serum first, while the skin is slightly damp, and then follow with a moisturizer to lock in that hydration and support the barrier,” says Dr. Queller. Those product categories are no accident, either. A face serum, which typically delivers a high concentration of active ingredients, is designed to more easily penetrate skin; thicker textures like a cream, meanwhile, can help create a physical barrier over that.
