[Updated Review] OST Original Pure Vitamin C20 Serum

Finally Β I get to try and review this highly raved serum!! I read A TON of great reviews on this and I think I haven’t found any that state it’s not working for them. Of course, me having a lot of acne scars also want to try this amazing serum by myself!

This is the first serum that I’ve tried (I think) and since there are so many great reviews on this, I have high expectations. But then again, my skin is a bit sensitive and weird, so I’m not hoping for a one-week-transformation. But let’s see what this serum does for me in one week!

OST Original Pure Vitamin C20 Serum

This serum comes in a box. The box is quite sturdy because it has cardboard inside which keeps the box from being destroyed xD The box is reddish orange and pretty glossy. Definitely not in the cute side for packaging, I guess they prefer the form-follows-function (what?) kind of packaging. The bottle contains 30 ml.OST Original Pure Vitamin C20 SerumOn the sides and the back of the box, everything is written in Korean. They listed the ingredients as well, but also in Korean. I decided to grab the ingredient list from cosdna and will post it below this paragraph πŸ™‚ They also listed the how-to-use and probably a warning for allergies and what not.

OST Original Pure Vitamin C20 Serum ingredientsClick for larger picture!

OST Original Pure Vitamin C20 SerumIt has a caution on the top of the box. 냉μž₯보관 means refrigerate. I’m not sure about the exact meaning, but the point is this serum is supposed to be stored in a cool place, and to put it in the fridge is the best. The sentence in white below it κ°œλ΄‰ ν›„ μŠ€ν¬μ΄λ“œλ‘œ κ΅μ²΄ν•΄μ„œ μ‚¬μš©ν•˜μ„Έμš” means after opening, replace the cap with the dropper tool.

NOW let’s see the product!

OST Original Pure Vitamin C20 Serum

OST Original Pure Vitamin C20 Serum

OST Original Pure Vitamin C20 SerumThe bottle is sealed with plastic wrap and you get the dropper in the box too. Right after you open the cap which is a twist off type, you will use the dropper as a cap instead of the regular twist off cap. The dropper is made of clear glass, so be careful not to drop it or it will break to pieces. The bottle is also made from amber-coloured glass. The bottle glass is pretty thick so it can endure a little bump here and there as long as you don’t hit it too hard.

The amber-coloured glass is used because vitamin C is known to be oxidized easily. It will respond to heat (high temperature) so make sure you keep it in the fridge. Stop using the serum if it’s already oxidized. How do you know if it’s oxidized or not? The color of the serum will gradually turn to orange. And when it’s orange, you should stop using it.

OST Original Pure Vitamin C20 SerumThis is the color of how it’s supposed to look like when you first open it. The color of the serum is pretty much transparent and clear with a hint of yellow. Mine already got yellower (is that a word?) but it’s not that yellow yet so I still use it. The quality of the dropper is very nice, it’s easy to take the product and it’s easy to control how much you want to squeeze out, too.

OST Original Pure Vitamin C20 SerumClick the image for bigger… image? haha You know what I mean!

To be honest, I found this serum to be very sticky upon applying. I feel like it’s hard for my skin to absorb the serum, but I decided to just slap on the Mizon snail cream on top of the serum without waiting for it to be not sticky. Well, it’s not that sticky anymore after I apply the snail cream πŸ˜€ I need around 3-5 minutes to absorb it completely. Although being sticky, it is very easy to spread, it feels like water.

It has citrusy scent which reminds me or oranges! Fortunately it doesn’t sting or tingle my skin at all, so I think my skin is not that sensitive and if I use it correctly my skin will love this ^_^ Here is the improvements of my skin in 7 days, using this serum twice a day.

OST Original Pure Vitamin C20 Serum

OST Original Pure Vitamin C20 Serum

OST Original Pure Vitamin C20 SerumClick the image to see it bigger

If you notice, I do lose some acne scars on my cheeks and my skin tone got a bit brighter. Too bad I also got new acnes on my cheeks when I use this. I don’t know if it’s because my skin hate it, or my skin hadn’t get used to it yet. I’m planning to mix this serum with my snail cream so I won’t use as much as if I’m using the serum by itself. My skin looks more dewy, but it gets oily faster than usual. I love how it helps to get rid of the scars! I just need to find out how my skin want this serum xD Oh, my skin gets a bit red when I use this, maybe because I don’t use sunscreen .__. And staring at my face shot up there make me realize I have a crooked jaw LOL

Positive sides

  • Brightens skin tone
  • Fade acne scars
  • Highest vitamin C concentration in serum by far (20%)
  • Citrusy scent
  • No bad ingredients
  • More dewy, healthy looking face
  • Easy to spread
  • Doesn’t sting or tingle at all
  • IDR 270,000 for 30 ml which will last for months

Negative sides

  • A few acne comes out on my skin, not sure if it’s caused by this or not
  • Sticky, hard for my skin to absorb
  • Skin gets oily faster than usual
  • Have to keep it in the fridge

Rating :Β β™₯β™₯β™₯β€’ 3.5/5

Will I repurchase this? Sorry, but probably no. I have stopped using this everyday in the August, only once in a while. If I find a good way to use this, I will definitely repurchase this. Don’t worry, I’m still planning to use this till it turned orange xDD

I’m super sad that this serum didn’t give me the result I expected. Well, it’s only for a week so I can’t really hate this serum πŸ™‚ I really hope this serum will help me to get rid of all of my acne scars. I won’t even hope for skin brightening effect because that’s too much to wish for xD I really want to give this serum a full rating, but I think it’s not time yet hahaha Like usual, I will update this post if I notice anything different!

Have you tried this OST serum? Do you like it?

Or do you use another serum for your face? Let me know in the comments! I really want to know what works for other people πŸ˜€


I finally have found a way to use this AMAZING serum on my face without causing more acne! Read down below ^_^

I only apply it once every other day (once in 2 days) and only in the evening. I apply Kiehls and Mizon on top of this serum and let them work together to improve my skin. This combination works so good! Here’s a little illustration. I apply the serum on Monday evening right after I get out of the shower. Then I apply Kiehls, and Mizon Snail Gel Cream as the last. It still feels sticky on me but I don’t mind now. Probably because I don’t wait until the serum completely sinks in? I don’t really know. Then I only use Kiehls and Mizon on Tuesday (morning and evening) and Wednesday morning. On Wednesday morning, I will apply this serum, top it off with Kiehls and Mizon again and the pattern continues.

I have been doing this for 2 weeks and I see no new acnes. The current acnes dried up faster than usual, and my face is brighter too. The scars are fading on a faster rate than before. Oh, I changed my facial wash to an acne facial wash. I will review a lot of stuffs on December, and if this routine really clears up my skin, I will post a detailed things that I actually do along with the skincare combination ^_^ I’ll cross my fingers!


19 thoughts on “[Updated Review] OST Original Pure Vitamin C20 Serum

    1. Yashhhhh that’s why I want to use this again xD
      Fortunately (or unfortunately?) I stopped getting acnes when I stop using this and only use the SK II FTCL and Mizon snail cream. Weird, eh? I just hope the acnes are not because of this .___.

  1. Wow! Finally i found the review that combined this serum with Mizon All In One Snail Cream.
    Hmm, i guess the new acne probably appeared because the ingredients of these two are not entirely match?

    1. I personally think the new acnes appeared because my skin is not used to the serum yet. I noticed that everytime I try new products, I will always get new acnes on the first week of use.
      But maybe we’re supposed to combine the serum with the 9 to 5 Crema, not with another creams (if that makes any sense xD)

  2. Iam half korea but my skun doesn’t suits of any korean skincare brand.I really meant it.Any korean brand.From high end range such as the history of whoo to etude house.I dont know why but maybe some herbal ingredients of those korean brand doesnt suits my skin veru well.And I’d almost purchased ost serum by many huge positive reviews.But while you mentioned it sticky on ur skin I def wouldnt ever give this one tried.I hv fair oily skin with no pimples nor even acne scars.Though I have to being loyal to my SKII regime instead of flirting with another skincare.Lol.thx a bunch dear.

    1. Aww that’s too bad 😦 I adore korean skincare because they seem to emphasize on natural ingredients and it’s made for Asian skin hehe Though not all suit my skin 😦

      This serum sure is on the sticky side, but only if you apply this by itself. If you apply moisturizer afterwards, the moisturizer actually sinks in my skin a bit faster than usual. I haven’t use this again so I can’t say more 😦

      Your skin sounds awesome! I guess the SKII worth the price for you ^_^ Thank you for stopping by! I’m glad that this helps~

    1. Wah iyaaaa? Aku belom pake lagi soalnya udah kuning banget skrg, lagi mikir2 mau beli lg atau engga soalnya agak mahal (tapi bisa dipake lama banget, cuma kalo ga cocok kan sayang hehe). Tebakanku sih itu keluar jerawat lagi karena purging gitu, mungkin kalo waktu itu diterusin bisa jadi bersih :p Tapi berhubung waktu itu kaget krna tiba2 nongol jerawat jadinya di stop dulu deh XD

  3. Hi Sherly
    My skin also had the same reaction as yours when I tried this serum 😦 I got quite lot of new pimples and my skin is usually pretty tolerant to any skin care. At first I wasn’t sure whether this serum was causing the pimples but after reading your blog (sadly) I am sure it is. Thanks for sharing!

    1. Hi Lisa! Sorry for the late reply and thank you for stopping by! ^_^
      How long have you been using this serum? By the time I want to give this serum a second try, it already oxidizes so I have to throw it away. I don’t know if I want to buy this serum again because I’m afraid it will be a waste of money T_T

  4. I am considering buying this serum and the vitamin night cream. Is it only for Asian skin or is it ok for western users? I read it is used to whiten skin, which I don’t want or need ( I’m already very pale, being Scottish) I don’t have acne or scarring, but I would like to use it it improve skin tone and generally make my skin better. Any thoughts?

    1. Hi πŸ™‚
      I think everyone can use this product. I haven’t read anything that states this is catered specifically to Asian skin. Personally, I don’t think using this will whiten anyone’s skin more than their natural skin color. If you had a tan, then this will help you to get back to your natural skin color πŸ™‚
      As for evening out the skin tone, this will definitely do the work.
      Note that this is a bit sticky. They have the improved formula of this same product with higher concentration of Vitamin C, the 21.5 (instead of 20) and people said it’s less sticky and absorbs faster! πŸ˜€ I haven’t tried that one yet, but seems like people also rave about it πŸ™‚

  5. Hello …
    My skin is combination oily..and quite dark complexion..i am searching a product which can actually brighten my skin.. i want to buy this product..but is it really works? Little bit confused…

    1. Hi Tasfia,
      For me, it does work for brightening my skin. But I will not recommend this if you have a lot of active acne on your face. Since the Vitamin C is pretty high in this product, it might aggravate active acne.

  6. Hi so im thinking of buying this serum. I got a lot of acne scars that need to get rids off lol
    I have clogged skin now on my cheeks, is it okay to start using this serum or do i have to wait till its unclogged?

    Is it gonna irritates you for newbie user since the concentration is high?

    And do we need a ph adjusting toner? Or any toner will do. Im using laneige trouble relief toner btw.

    1. I think it depends on each person’s skin. Have you ever use any product with Vitamin C before? As far as I observe, this serum won’t do good if you have active acne, so I’m not really sure about clogged skin. If I were you, I will wait until my skin is unclogged just in case.
      I don’t experience any irritation despite the high Vitamin C content, but if you have super sensitive skin or you want to prevent, you can mix this with your moisturizer so the concentration will lower down a bit.
      I haven’t tried this with pH adjusting toner, so I can’t really say anything about that. I’m sorry 😦

  7. Hi ive been reading any testimonial ’bout this one, then offically i bought too hopefully this serum can remove my acne scars and its the first week i try but unfortunatelly my skin get some pumple like us. I want to using this product mix with vitacid 0,05% a.k.a Vit A, this product its much better to healing my acne skin so can you give me advice may i using this product wit vitacid to prevent acne and remove acne scars?

    1. Hello!

      I’m so sorry, but I’m not really sure if you can use the OST C20 together with Vitacid or not. I have no medical background whatsoever, except from reading other people’s blog and my own experience. My advice is either to do a patch test first on a small section of your skin, to see if both products have a clashing ingredients or not; or to use the Vitacid at night and C20 in the morning so they won’t clash directly.

  8. Hi Stephanie, I was reading reviews of this product and had read your blog. I think this serum, the ost serum, is not recommended to use when you actually have pimples or acne breakouts rather used it to get ride of the acne or pimple scars. Thats only my opinion.

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