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15 Best Prime Day CosRx Deals I’d Recommend Following My Visit for Seoul
What is CosRx?
The best CosRx products were iconic long before coveted Korean glass skin became mainstream. “It {CosRx} became a cornerstone brand in the early K-beauty wave we introduced through our curation at Soko Glam,” says Charlotte Cho, a licensed esthetician based in New York City and cofounder of skin care maker Then I Met You and online retailer Soko Glam.
Cho personally introduced me to some of CosRx’s best-selling snail mucin skincare in 2016, and I’ve been a fan ever since. “Their approach is simple yet effective — science-backed formulations, affordable, and results you can actually see,” says Cho.
Note that it’s not just in the West where CosRx is big news. Founded in 2013, CosRx is also well-known in South Korea, where it’s gained a loyal following for prioritising results with minimal irritation. “In Korea, CosRx is widely known for its no-frills, ingredient-focused approach to skin care — especially for acne-prone, oily, or sensitive skin types,” says Hwang Wonuk, MD, cosmetic physician at Cheongdam LeBelle Dermatologic Clinic in Seoul.
How I tested CoRsx products
Since my introduction to K-beauty brands in 2016 (coincidentally, the first K-beauty brand I ever tried was CosRx), I’ve gravitated toward their innovative delivery systems and gentle efficacy.
Over the years I’ve tested hundreds of the most popular launches, including snail mucin creams, cleansing oils, lip tints, and cushion foundations. I even spent three months in Seoul last year researching the latest emerging trends and viral Korean skin care launches.
During that time, I visited CosRx’s headquarters in Seoul, where I tested every single product from the brand. When reviewing each CosRx formula, I make note of its ingredient list to determine which skin types it’s best for, whether it’s fragrance free, and what its key benefits are. Once I’ve got a view on each product, I also consult with K-beauty experts and dermatologists specialising in Korean skin care to curate each list and help Glamour readers make the most informed decision. Read more about how we test here.
1. Best Cleanser: CosRx Low pH Good Morning Gel Cleanser
All skin types can benefit from this gel cleanser, which I personally love for its gentle, non-stripping formula. Dr Hwang credits its versatility to the ingredients, which include tea tree leaf oil to “soothe inflammation and help manage acne-causing bacteria,” beta-hydroxy acid (BHA) to “gently exfoliate and prevent clogged pores,” and allantoin to “calm skin and aid in barrier repair.” Together, they create a formula that deep-cleans without feeling harsh on your complexion. “This is one of the few Korean cleansers I recommend consistently to patients starting prescription actives or post-laser treatments,” says Dr Hwang. “It cleanses thoroughly without disrupting the skin’s natural pH, which is critical in maintaining a healthy barrier. Personally, I’ve used it after procedures like microneedling, and it never causes tightness or irritation. It’s a solid, gentle cleanser that works especially well for oily or acne-prone skin types.”
Cho also swears by this pick, which she says has been a staple in her skin care routine for years. “It’s gentle, has the perfect low pH to support my skin barrier, and never leaves my skin feeling tight—just fresh and balanced,” she says.
2. Best Essence: CosRx Advanced Snail 96 Mucin Power Essence
Original video from Sarah Y. Wu testing CosRx Advanced Snail 96 Mucin Power Essence
Snail mucin is one of the most popular Korean beauty trends. Y. Claire Chang, MD, a board-certified dermatologist at UnionDerm in New York, previously told US Glamour that snail mucin (or snail secretion filtrate) is “rich in amino acids and hyaluronic acid,” giving it hydrating, repairing, and brightening benefits. “I love this essence, especially as an extra step in the winter when skin may become dry, chapped, and in need of repair,” she says. Cho is also a loyal fan of this well-known formula. “This essence was one of the first snail products I ever used, and it truly converted me. The texture is hydrating and bouncy, and over time, it helped smooth and calm my skin like nothing else,” she says.
I’ve also used up several bottles of this essence over the years and love how it balances intense hydration with a bouncy yet lightweight formula. It’s perfect for imparting instant bounce to the dry zones of my combination skin without breaking me out or making my T-zone feel greasy.
3. Best Serum for Dry Skin: CosRx The Hyaluronic Acid 3 Serum
Original video from Sarah Y. Wu testing CosRx The Hyaluronic Acid 3 Serum
Hyaluronic acid is a hydrating powerhouse popularised for its ability to intensely moisturise skin without heaviness. This face serum is part of the brand’s Rx line, which boasts especially potent ingredients. If you’re looking for a no-frills hyaluronic acid serum that pairs the hero ingredient with other popular hydrators such as glycerin, ceramide NP, and vitamin E, this is an excellent option. It absorbs quickly, layers easily with my other skin care and makeup, and keeps my face feeling hydrated all day. “When my skin is parched—especially during winter or post-retinoid use—I reach for this,” says Cho. “It sinks in quickly and delivers deep hydration without any heaviness.”
4. Best Serum for Oily Skin: CosRx The Niacinamide 15 Serum
Original video from Sarah Y. Wu testing CosRx The Niacinamide 15 Serum
Another standout from the Rx line is The Niacinamide Serum, which is formulated to help keep oily and acne-prone skin types balanced, clear, and smooth. Niacinamide is one of the most versatile skin care ingredients—treating concerns from dark spots and hyperpigmentation to dryness and redness—so technically any skin type can benefit from its effects. But this serum is especially great for balancing sebum levels and keeping blemishes in check thanks to its high concentration of niacinamide (15%) paired with acne-fighting zinc PCA and soothing allantoin.