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The MULTIPLIER™ Hi-Performance Vitamin C Serum


Night-time Use Highly Recommended

3X Penetration of Regular Vitamin C

2X Collagen Synthesis

Stable Tetrahexyldecyl Ascorbate plus Ferulic Acid


1 Fl Oz White Glass Dropper Bottle


In stock (can be backordered)

The MULTIPLIER™ Hi-Performance Vitamin C serum uses stable, oil-soluble,Tetrahexyldecyl Ascorbate (THDA) and Ferulic Acid for OUTSTANDING anti-aging results.


  • 3x Penetration of L-Ascorbic Acid
  • 2x Collagen Synthesis
  • 50% Increase in Fibroblast Proliferation
  • 80% Decrease in Melanin Overproduction
  • Inhibits MMP Activity (MMPs are aging enzymes that decrease collagen synthesis)


Even sensitive skin can tolerate this superior formula. The pH is higher (less acidic so less likely to be irritating) plus the addition of  beta glucans soothes and hydrates the skin. Ferulic Acid boosts the THDA’s powerful anti-aging properties to give you faster results.

We recommend that the Multiplier™ Hi-Performance C Serum be used as your “night-time” vitamin C serum since it takes up to 3 hours to achieve the antioxidant properties that the L-Ascorbic Acid in our C+ Firming serum achieves immediately upon application.

So use your C+ Firming serum each morning for the ultimate in free radical protection and apply the Multiplier™ each night when your skin repairs itself and works to produce more collagen and elastin.

With 3x the penetration (all the way into the dermis) and twice the collagen synthesis, you can look forward to skin with the “snap back” of much younger skin.

For clinical information on Tetrahexyldecyl Ascorbate, click here.




Optimally, use each night as your night-time antioxidant super-hero.

Apply to cleansed, toned skin along with other serums/complexes but before any moisturizers/sunscreen. 

A few drops should be enough to cover face and neck. Can be used under and over eyes as well.

Massage in gently, focusing on areas where collagen stimulation is most needed.

  1. :

    I posted a review for The Multiplier a year ago and said I would try it for 6 months before deciding – I am glad to report I’m still using this product and give it a “thumbs up”! My skin has never been so smooth and soft. I have oily skin and suffered from acne as a teen. Besides the texture, my complexion looks brighter. In additon to the Vitamin C+ and Multiplier, I’ve added the skin cleanser and toner to my daily routine and they control the oil well.

  2. :

    I tried the ‘famous’ vitamin C and ferulic acid serum a few years back, and it was just too expensive to use long enough to see if it was an improvement over the C+ serum. Silly me–I should have waited till CSRx had a ferulic-C combo. I have been using the Multiplier for the past few months, and it’s everything I hoped the ‘famous’ serum would be at a fraction of the price. I’ve learned my lesson–stick with the products at CSRx–proven effectiveness at a reasonable price.

  3. :

    I have been using the Multiplier each night for about 3 months and am seeing continuous improvement over time – specifically in skin color and texture. The tip of my nose and chin are noticeably smoother, pores are tighter, and my skin color has evened out. I exfoliate with a scrub about twice a week (which definitely helps) but had not seen such a dramatic improvement until adding The Multiplier. I am seeing continuous improvement week over week. I love that it is so concentrated yet does not irritate my sensitive skin, and delivers cumulative improvement over time. This one’s a keeper 🙂

    • :

      Thanks, Carol! I love it, too!

  4. :

    I have been using the Vitamin C+ Firming Serum and Niacinamide((CSRx Transforming Infusion Serum Concentrate) cocktail since the introduction of the CSRx Transforming Infusion products, so I had no hesitation in trying the Multiplier when it was introduced. I have not been disappointed and am ordering my 2nd bottle now. I love the creamy texture and blends nicely. I also can see results at a time when I am only wearing sunscreen.

  5. :

    I was introduced to the Vitamin C+ Firming serum last year and I have been using it during the day. I’ve been looking for a new night time serum as the last one I bought from a high end department store wasn’t worth the high price I paid for it. Enter The Multiplier. It was just the thing I was looking for! I’ve been using it for about a month and like the way it goes on my skin at night before I go to sleep. It has a light, pleasant smell and isn’t sticky or oily. I did have a huge zit last week so I hope it’s not related to this product. I plan to try it for 6 months before rendering my final verdict. I am 65 yrs old with problem skin my whole life. I believe I can see a difference!

  6. :

    I have been using Vitamin C+ Firming serum with Antioxidant defense complex for the evening regimen for a long time, but I decided to try the new Multiplier nighttime C.
    So far I have been very pleased with this creamy and silky texture and will definitely continue to use this for nighttime.

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Active Ingredients That Work™:
Tetrahexyldecyl Ascorbate, Squalane, Beta-Glucans, Ferulic Acid, Jojoba Seed Oil, Sodium Hyaluronate, Tocopherol, Rosemary Extract, Sunflower Seed Oil

Other Ingredients:
Water, Caprylic Acid, Behenyl Alcohol, Lecithin, Sorbitol, Xanthan Gum, Disodium EDTA, Arachidyl Glucoside, Dehydroacetic Acid, Propanediol, Maltodextrin