Glowhan — Korean Skincare Guide | glowhan.shop
Five actives carry most of the routine: hyaluronic acid, niacinamide, retinoids, vitamin C and AHA/BHA — each with a role, a strength and a caution.
Hyaluronic acid can bind up to about 1,000 times its own weight in water. It is a humectant used in essences and serums for dehydration, and its strength is hydration rather than exfoliation or brightening.
Niacinamide supports the barrier and is one of the gentler actives; it is commonly layered in serums without the timing restrictions that retinoids carry.
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Retinoids increase the skin's sensitivity to sunlight, so they are used at night and paired with daytime sunscreen. That caution is the strictest of the five and it is the reason the routine's last step is non-negotiable for retinoid users.
Vitamin C is an antioxidant typically placed in the morning layers, before moisturizer and sunscreen. AHA and BHA are exfoliating acids used in the third step of the routine; they are not combined with retinoids in the same evening for most people.
Strength is not the same as frequency. A high-strength acid used daily breaks down the barrier that the moisturizer step is meant to protect, which is why the exfoliant step is not an everyday step for everyone.
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