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Quick Product Notes
(Click on Icons for more information)

Paraben-Free
Sulfate-Free
Alcohol-Free
Silicone-Free
EU Allergen-Free
Fungal Acne (Malassezia) Safe

Notable Effects & Ingredients


Brightening from 3 Ingredient(s):
Glutathione Niacinamide Ascorbic Acid (Vitamin C)

Anti-Aging from 2 Ingredient(s):
Niacinamide Ascorbic Acid (Vitamin C)

Promotes Wound Healing from 2 Ingredient(s):
Panthenol Sodium Hyaluronate

Ingredients Related to Skin Types
Click on the arrow next to the Skin Type! Green = Good & Red = Bad

Dry Skin
6
1
Oily/Acne-Prone Skin
1
Sensitive Skin
1

Ingredient Safety Breakdown (EWG Health Ratings)

  • Low Risk
  • Moderate Risk
  • High Risk
  • Unknown
90%
0%
0%
10%

My Ingredient Notes

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Product Ingredient List

(Showing first 5 of 21 Ingredients)
EWG CIR Ingredient Name & Cosmetic Functions Notes
1
Water
(Solvent)
1
A
Ascorbic Acid (Vitamin C)
(Skin Conditioning, Masking, Fragrance, Antioxidant, Ph Adjuster, Buffering Agent)
Brightening
Brightening
Anti-Aging
Anti-Aging
Good for Dry Skin
Good for Dry Skin
2
Alcohol
(Solvent, Masking, Viscosity Controlling, Antifoaming Agent, Antimicrobial, Astringent)
Bad for Dry Skin
Bad for Dry Skin
Bad for Sensitive Skin
Bad for Sensitive Skin
Alcohol
Alcohol
1
A
Niacinamide
(Skin Conditioning, Hair Conditioning, Smoothing)
Brightening
Brightening
Anti-Aging
Anti-Aging
3
B
Sodium Lactate
(Humectant, Buffering Agent, Exfoliant, Keratolytic)

Latest User Reviews

Write a Review
Review
1
Points
225
Badges
0
Allergic reaction
Reviewed
Skin Type: dry Skin
Skin Concerns: Post Inflammatory hyperpigmentation (PIH), Acne, Blackheads, Large Pores, Dehydrated Skin, Uneven Skin Tone, Whiteheads/Closed Comedones

I've tried both OST C20 and C21.5 and was satisfied with how they made PIH disappear (C20 results were better!). I wanted to try this version but got a severe allergic reaction, my face became red, swollen and was itching so bad (I didn't patch test because I didn't think it'd happen, stupid me!). Make sure to PATCH TEST!! I don't think that I even have a sensitive skin but please make sure to patch test (wow!I said it 3 times!).
P.S. I just noticed some other reviewer had a similar reaction. I'm trying to figure out which ingredient caused it so, If you have any idea, please tell us orz
I gave it 1 star because of the allergic reaction. It may work for you, tough!

Review
22
Points
915
Badges
0
I miss the older version
Reviewed
Skin Type: oily Skin
Skin Concerns: Acne, Anti-Aging (Fine lines & Wrinkles), Blackheads, Large Pores

I bought this serum for its promise related to faster effects and that it'd have more stability than its successor, but the truth is that it has turned out to be very very bad. The smell is similar to raw meat, and once it opens it begins to bubble as if it were soda. It absorbs fairly quickly and leaves no sticky sensation as its previous version, but I wouldn't recommend it without performing the patch test first. My skin had a severe reaction and it became red, swollen and itchy. Even when I use it with other serum or toners, it feels hot and my skin turns red. Please be very careful if you're going to try it, especially if you have sensitive skin. I'm still trying to find out why this reaction is caused, there are already several similar cases among my relatives.