Review: OST/C20 Original Pure Vitamin C20 Serum | Hello Pretty Bird! - A beauty and not-so-glamorous lifestyle blog

27 October, 2014

Review: OST/C20 Original Pure Vitamin C20 Serum

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Today I'd like to introduce you to a wonderful skincare product that gives me that warm and fuzzy feeling: C20 Original Pure Vitamin C20 Serum. (Literally. It tingles for a few minutes after I apply it.) In all seriousness though this is a good Vitamin C serum available at a very reasonable price (in my opinion), so read on if you're in the market for such an item!

OST C20 Original Pure Vitamin C20 Serum Vitamin C box

Quick note about the name: Some of you may have seen a similar-looking product branded as OST Original Pure Vitamin C20 Serum—it's the same thing as this. They rebranded it as "C20 Original Pure Vitamin C20 Serum" earlier this year. Not sure why as the new name is a bit redundant, but in any case it's the same thing inside the bottle.

Speaking of bottles, OST/C20 serum comes packaged in a standard glass vial to prevent leaking, but there is a handy-dandy dropper in the box for you to use once it's safely unboxed and in your hands.

OST C20 Original Pure Vitamin C20 Serum Vitamin C dropper bottle

Fancy. Ingredients:

OST C20 Original Pure Vitamin C20 Serum Vitamin C ingredients

The only weird thing I see on this ingredients list is Niacinamide—not a bad ingredient by itself, but my understanding it loses its effectiveness when mixed with Vitamin C, and can sometimes cause flushing if present in an acidic formula (which this is). So why is it in there? Shrug.

According to the product page on WishTrend, this serum is meant to:

  • Whitening (in the sense of overall skin tone brightening)
  • Recovering trouble scars (reducing PIH/post-acne marks)
  • Removing blackheads (by exfoliating, I imagine?)

The form of Vitamin C present in this serum is Ascorbic Acid, which is supposedly makes up about 20% of the overall formula. I obviously don't have a way of testing that, but what I can tell you is that I tested a bit of the formula on some home testing pH strips, and got a result of about 3 (accuracy not guaranteed, of course). That would make this product acidic enough to actually penetrate the skin, which makes me think the blackhead-reducing claims are probably true. (I don't have an especially large amount of blackheads myself, so it's difficult for me to notice real results in that regard.)

OST C20 Original Pure Vitamin C20 Serum Vitamin C texture consistency

The texture of the serum is sort of viscous and slippery—thicker than water, but still very runny. It has a very faint yellowish color and smells vaguely sour (like citrus, not rotten milk). It's actually a good idea to keep an eye on the color of your Vitamin C serum, because if it darkens noticeably that probably means the product has oxidized and is no longer good to use. Make sure to store the product in its original bottle (which is made of dark glass) and keep it away from heat/sunlight to increase its longevity. With that said, the shelf life of the product is still only about three months, so use it while you can!

Aaaaaanyway. I use this serum as part of my daytime routine because I don't want it to interact badly with the Tretinoin/Paula's Choice BHA I use at night. (FYI, I used to use the BHA during the day, but now I alternate it with Tretinoin as part of my nighttime routine. You don't want to mix the two. Exciting!) I think C20 might actually be better to use this as a nighttime product as well because the Ascorbic Acid could get broken down by exposure to the sun, but if you're the indoorsy type (like me!) that is perhaps not such a big issue. Plus sunscreen and floppy hats are a thing.

Here's where it fits into my routine:

  • Wake up
  • Lament on the onset of the day
  • Cleanse face (I usually use CeraVe Foaming Cleanser in the morning, if anyone cares)
  • Apply a few drops of OST/C20 serum to face
  • Experience a mild to moderate tingling sensation from the serum
  • Wait 10-15 minutes for the tingling to neutralize
  • Apply other skincare (moisturizers and whatnot)
  • Lament the onset of the day

Some people probably apply this over or mixed with a toner, but I like to just go all in like a wild woman. The result is a slightly tingly, flushed feeling immediately after application, but I find that it goes away after a few minutes. YMMV so be sure to test patch if you have sensitive skin.

Overall impressions:

I've been using this serum for about a month now and I *LOVE* it! I have no idea if it's doing anything to remove blackheads, but my skin definitely feels supple and my overall complexion looks a bit brighter, in my opinion. I also had some acne scarring which seems to have faded a bit more rapidly than normal since introducing this into my routine. OST/C20 is the third Vitamin C serum I've tried, and so far I think I like it the best—jury's still out on Paula's Choice C15 serum (another popular choice that I have dabbled with but will test more extensively and review in another month or so). But the bottom line is that I do think OST Original Pure Vitamin C20 Serum is effective and quite reasonably priced too.

Where to buy + coupon codes:
You can purchase OST/C20 Original Pure Vitamin C20 Serum from WishTrend, where it is currently on sale for $14.99 plus free shipping (regularly $24.99 for 30ml). Even better yet, new customers can get a $5 voucher to use towards their purchase of $30+ by entering my referral code in the "Friends Invitation Program" field when signing up or filling out the "Additional Information" section of their profile: 252963208. All orders over $69 ship free at WishTrend, just FYI.

What do you think of OST/C20 Original Pure Vitamin C20 Serum? Do you have any favorite Vitamin C serums you'd recommend?

Disclosure: The item featured in this post was provided to me for review purposes, however any opinions expressed above are honest and my own. I did not receive any other form of compensation. This post contains affiliate links. For more information, check out my full disclosure policy.


  1. I love serums, but I'm allergic to anything citrus. Sucks! I love bottles with droppers, though. I wish more products had them, because it's so much more handy at getting the last drops!

    Wendy | Fashionable Heart

  2. Ah that's too bad! Best avoid this then as it contains a bit of orange oil.

  3. I'm really curious about this serum! I've seen it a few places and it's got my mind buzzing. It sounded like it worked for you really nicely, which is always a pleasant result ;) maybe if I ever get to the bottom of my current stash I could give it a go. Nice review! ^-^
    Steph | Misc. Bliss

  4. I love this stuff! It's made such a difference in my skin. Although, two drops really doesn't seem like a lot! I use half a dropper every morning... I guess I use a lot because I'm worried about it oxidising before I use it all.

  5. I should probably rephrase "two drops" as "two squirts" from the dropper. Not sure how much that actually is, but I like to start light and add more if needed because too much makes my face sticky!

  6. I've read some reviews of it before and the overall consensus seems positive! I think it doesn't hurt that it's pretty affordable compared to some other Vitamin C serums (like the aforementioned Paula's Choice serum).

  7. I love this serum, too. It makes such nice effects within short time already. I'm definitively going to buy it again soon.

  8. I haven't tried this serum, but I love vitamin C serums. I have a stockpile in my collection that I'm trying to finish up! This sounds like a nice serum.

  9. I think I will too! I still need to use up the Paula's Choice serum though ... guess I should decide which one to get then!

  10. If you ever work through your stockpile, this is a good one to try! They go "off" after a few months anyway so you'll have to replace them sooner or later.

  11. Glad that this works well for you! There are so many serums out there and it gets pretty overwhelming lol

  12. I'm so glad to hear you like it so much! I like that it's not super expensive (as I find most serums are...)

    Ivory Avenue

  13. This serum sounds wonderful~ ^ w ^
    I would love to experience the warm and fuzzy feeling it gives! ^ u ^

  14. I've been using it quite liberally over the last few months, and I noticed that it stains my skin a bit orange... I've now started to use it every other day, and I only use a bare minimum amount on my skin. With these changes I've noticed the orange look has significantly reduced. Have you noticed this before?

    Other than has really really lightened my PIH and cleared up my skin's splotchy look!

  15. No, not in the slightest! Is your serum a light yellowish color like the picture above? If it's much darker it may have oxidized, in which case you should stop using it and get a new bottle. But I've never noticed any skin staining from this product - bizarre!

  16. Very true. I guess the trick is figuring out what you want your serum to do and go from there. I think this serum is especially good for people who have post-acne red marks they want to fade.

  17. Agreed! The Paula's Choice C serum is like twice as much, gasp!

  18. It is a bit darker than the colour in the picture above, so it may have oxidized =( Good point!! I'm almost finished the bottle anyway. Luckily I have two extra bottles stashed away :D

  19. I am always on the hunt for vitamin c serums that don't break me out and actually work, so I'll have to pick this one up at some point! I recently found one that has been working wonders, but it's only been a week or so...I may need a back up if I sprout a field of acne tomorrow! LOL Thanks for the review! :) #kbeautybloghop

  20. Glad to have found another person who appreciates the benefits of this serum. I've been using it for about three weeks already. Ordered it after reading quite a few reviews by beauty bloggers - ones whose blogs I've come to always read before making a decision to buy a beauty poduct - who were all of them, without exception, praising it. I am happy I got this bottle. I use the serum as a first step after cleansing every evening. I avoid the feeling of residual stickiness by mixing with a couple of toner drops.
    Result, and I trust the serum is greatly to be credited with it - my otherwise dry skin feels more supple and plumped up and is brighter and even in tone. Cannot comment on other claimed benefits as I have no acne or blackheads issues.

  21. I've never tried a vitamin C serum maybe the acidic thought scares me but this one sounds interesting. I do have blackheads from time to time so this may be a good product to try for that as lately my skin has been irritated by those blackhead removing strips! #kbeautybloghop

  22. It's definitely worth a try when you eventually run out! It's my favorite Vitamin C serum that I've tried so far.

  23. "Plumped up" is a great way to describe it. It does have a nice skin-plumping effect. I find that my face is a bit sticky immediately after application, but once I let it settle for a bit and apply moisturizer over it, it goes away.

  24. I wouldn't be scared of mild acids - they're actually quite useful for exfoliating the skin. If you've ever used Stridex or something like that, that's an example of an acid (BHA). But yeah, those strips can really irritate your skin if you use them constantly! I'll still do it once in a while though just out of morbid curiosity, lol.

  25. 'Lament the onset of the day' haha... boy, can I relate. I recently began using what sounds like a very similar type of serum from Memebox and it's working out quite well. I'm glad you're seeing good results! #kbeautybloghop

  26. Do you remember what the exact name of the serum was? Just curious. I like this one a lot but I can't help but want to compare it against others, haha!

  27. Are you supposed to keep the serum on without washing it off?

  28. Most people do leave it on for the antioxidant benefits, yes. If your main concern is removing sunspots/PIH/etc. though, you could use it as a wash-off treatment - you'll still get most of those types of benefits if you wear the serum for 20-30 minutes before rinsing.