The Good

• Enhanced Absorption Many users praised the serum’s ability to boost absorption of subsequent skincare: “The side treated with Sulwhasoo’s First Care Activating Serum was way less sticky because more of the 2nd serum I applied got absorbed.” (124 upvotes)
  • “It makes everything you apply more effective and absorb better.” (7 upvotes)
• Noticeable Skin Improvement Some reported softer, more even-toned skin and better texture: “I adore it — it was the first serum I ever fell in love with. It made my skin really soft and played nicely with anything I layered under or on top of it.” (4 upvotes) “It calmed my skin, and even when I used it alone, my skin felt better.” (6 upvotes) “My skin tone is more even, skin less dull, pores minimized.” (6 upvotes)
• Synergistic Effects Users often found it performed best when paired with other actives: “The serum and SK-II essence together give my skin a nicer glow than the essence alone.” (5 upvotes) “Using FCAS and SK-II essence together really evens out my skin and gives it much more clarity.” (7 upvotes)

The Not So Good

• Reformulation Disappointment The new formula drew strong backlash from long-time fans:
  • “New formula is awful. It’s noticeably different. Stopped purchasing and using it.” (6 upvotes)
  • “New formula seems thinner and less nourishing. It feels diluted — I’m not a fan.” (6 upvotes)
  • “Nope. Not at all. Used to be, but now, no.” (20 upvotes)
• Lack of Results Others reported no visible improvements:
  • “It was meh… used all of it, didn’t feel any different.” (4 upvotes)
  • “I don’t think it does anything at all for my skin.” (4 upvotes)
  • “It literally does nothing.” (6 upvotes)
  • “After finishing an entire bottle — IT DOES NOTHING.” (7 upvotes)
• Skin Reactions A number of users experienced breakouts or irritation:
  • “I wanted to love this so badly, but it made me break out.” (10 upvotes)
  • “I have sensitive skin, but I read on their website it was suitable for sensitive skin. No. No it wasn’t.” (11 upvotes)

Comparison to Alternatives

• SK-II Essence A frequent comparison due to similar product category and texture: “Just finished the travel size — the way it absorbs is kinda similar to SK-II FTE honestly.” (6 upvotes)
• Estée Lauder Advanced Night Repair (ANR) One user found ANR clearly superior:
  • “Honestly, Estée Lauder ANR is far superior.” (7 upvotes)
• Sooryehan Ginseng First Essence Mentioned as a stronger ginseng-based alternative:
  • “It’s a good source of ginseng for anti-aging, but I personally prefer Sooryehan Ginseng First Essence.” (13 upvotes)

Tips and Tricks

• Correct step in Routine The most common mistake is using it at the wrong step:
  • “It’s a first-step serum that enhances the skincare you put on afterward. Works best with other Sulwhasoo products.” (13 upvotes)
  • “You’re supposed to use it after cleansing — Sulwhasoo says this directly.” (12 upvotes)
  • “Don’t be deceived by its thicker texture — it’s definitely meant as the very first step!” (7 upvotes)
• Pairing with Other Products Users shared routines where FCAS fit best:
  • “I use it after my actives and watery serums, before creams.” (8 upvotes)
  • “It’s my very first step in the AM before Melano CC; at night, I use it after my active, before other serums.” (7 upvotes)

The Verdict

Reddit discussions reveal a sharp divide between fans of the original Sulwhasoo First Care Activating Serum and those reacting to its reformulation. The earlier version earned loyal followers for its absorption-boosting qualities and subtle skin benefits, particularly as part of a broader routine.

However, the reformulated formula faced criticism for its alcohol-heavy composition, added fragrance, and reduced richness, leading many long-time users to abandon it.

For best results, users recommend treating FCAS as a booster step rather than a standalone serum, and to test sample sizes first, especially for sensitive skin.

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