Review: OST Original Pure Vitamin C20 Serum (aka TIAM C20 My Signature C Source)

Acne is a double whammy.  As any afflicted victim knows, the active lesions are only Part 1 in this tragic affair.  The leftover hyperpigmentation is Part 2, the gift that keeps on giving as it slo-o-owly fades over weeks and months.  Most days I leave the house with full foundation but even if I was a beauty guru (which I'm not!) make-up can only go so far to hide dark spots.  I already use chemical exfoliants to speed up the healing process and I gravitate towards products with ingredients like niacinamide and arbutin (superstars for further brightening) but I always welcome more pigment-busting agents that can lighten acne souvenirs more quickly.

Over the last few years I've turned to serums with vitamin C like the popular OST Original Pure Vitamin C20 Serum (aka TIAM C20 My Signature C Source now) and its updated version: Pure Vitamin C21.5 Advanced Serum.  The main benefit I'm seeking is the brightening effect but vitamin C is also great for collagen synthesis (yay plump skin!) and repairing sun damage so the aging prevention is a nice bonus.

Both versions come in 20 mL dark brown glass bottles with a rubber-tipped dropper.  These cool little bottles have a great vintage feel, especially after you remove the label, add your own and/or replace the dropper with corks.  (I've collected all my used ones because I'm a pack rat that's convinced I can DIY something with them in the future! =)  OST recently changed the original formula name and packaging to "TIAM C20 My Signature C Source" (the ingredients are identical) and my photos reflect the previous/original labels.

The best way to slow oxidation is to keep the serum in the fridge or at least a cool + dark location.  When oxidation occurs the pale yellow color becomes a darker orange and you know it's time to replace the product.  I've noticed the serum stays a pale yellow longer than 3 months if I keep it refrigerated but it's still advised to use it up within 3 months of opening.  Anything beyond is probably riskier, like eating expired food... we've all done it without problems but that one time it really matters you end up with diarrhea so best to be safe.... >_<

The ingredients list for both OST versions vary.  C21.5 has a much shorter one without the alcohol or parabens found in C20 so many consider it an improvement.  The "21.5" refers to the 21.5% of Vitamin C within the formula and I suppose an extra measly 1.5% counts in the fight against hyperpigmentation but I wouldn't consider that a huge reason to pick it over the C20.

There's a slight citrus + alcohol smell that fades quickly if that's not your thing.  The texture is thinner with the C21.5 so absorption is supposed to be better but after trying both formulas I feel both leave a sticky texture regardless so it's up to the user which feels best.  Do you want runnier or thicker?  (shrug)

I tried both formulas on and off over the course of a year.  At first I needed to apply an essence  before the vitamin C serum so the extra buffer would keep stinging to a minimum.  Eventually my face became less sensitive and I could apply directly after cleansing with only minimal tingling.  The burning was usually worse when I had broken skin/breakouts or my skin just felt extra touchy.  In the end my wallet made the executive decision to stick with the C20 because C21.5 costs more $$ and I wasn't concerned with the different ingredient list. 

Since I use a BHA in the mornings I saved my vitamin C serum for afternoon after I washed off my make-up.  In the evenings I'd cleanse my face again (usually after working out) so this product probably only stayed on my face several hours max per use. In general I was too lazy to use the product every day because I didn't want to make the trip to and from the fridge where I stored it.  ^_^ I suppose I would have been more motivated to apply it more than ~3x/week if I saw really great results but I always considered this product a "something-I-should-be-using" skincare item rather than a Holy Grail.

Eventually I made the decision to stop completely because I went through 2 months without using any (ran out and didn't buy more) and felt my skin was either the same or better without the serum in regards to breakouts and hyperpigmentation.

Warning: ramblings to follow... skip to the bottom to avoid text heavy ranting!

During those 2 months I neglected the OST serum my chin was smoother and I rarely got cystic breakouts (the large and hard variety that take weeks to smooth out).  I didn't realize it wasn't coincidental until I re-started the serum and my skin became more troubled again!  It took nearly a month of frantic doubt ("Was it the extra ice-cream from 2 weeks ago?  Costco parmesan cheese chips?!  Extra helping of tofu at dinner?!) where I assumed my face was just taking revenge for my yummy but unhealthy food choices.  In the end, though, it was too much of a dramatic turnaround for me to accept so I kept sniffing around.  I got back to basics and re-checked the ingredient lists for everything I was slapping on my face including the OST serums and lo-and-behold.....

... My old enemy xanthan gum! O__O  It was innocently inserted midway down the ingredient lists of both formulas and pinged my radar because it's something I'm actively trying to purge from my diet and skincare.  I previously posted about my negative reactions to this thickening agent and keep randomly running into it.  It's an annoying surprise to see it pop up in products I assumed were free of acne triggers because I only used CosDNA and looked for highlighted ingredients without reading the actual list.  Xanthan gum doesn't get categorized as being comedogenic and I'm sure others have zero issues with this thickening agent but I react poorly to it whether it's in food or skincare products. For me, it's a frenemy that seems honest on the surface (oh here, lemme help smooth out your serum) but knifes you in the back (or face) with inflammation. =(

At the end of the day I'm dumping out my OST serums (waaah) and going to continue to searching for other skincare goodies to lighten dark spots.  Even if my hyperpigmentation faded quicker this serum was simultaneously creating more so I'm never re-purchasing.  I'm not closing the door on vitamin C products but I'm going to triple check in the future they don't contain xanthan gum.

Summary:

• Packaging:     5/5 (hygienic; elegant; prevents oxidation)
• Smell:             4/5 (mild alcohol scent but also citrus-y yum)
• Performance:  1/5 (breaks me out boo)
• Value/Price:    4/5 ($14-15 + free shipping on eBay/Wishtrend for 30mL; $25 for C21.5)
• Recommend? Maybe (for folks who aren't sensitive to xanthan gum or alcohol)
• Repurchase?  Nope (Begone!)