Citrix CRS 15% Serum with Growth Factor
1 fl. oz. for $108
Last Updated:12.10.2012
Jar Packaging:No
Tested on animals:Yes
Review Overview

This vitamin C serum is nearly identical to the Topix Citrix CRS 20% Serum with Growth Factor. Other than containing 5% less vitamin C (L-ascorbic acid), the same comments apply.

This serum is mostly a blend of silicones (which make the skin feel silky-smooth) plus a 15% vitamin C (L-ascorbic acid). With any active ingredient, you want to make sure the scales are tipped in favor of benefits, not irritation. This 15% is a high amount of vitamin C, and could be considered the threshold for anti-aging results without irritation, although there is no question that some people will still find this amount irritating. (It would've been nice if Replenix had added some anti-irritants.)

Despite vitamin C's benefits, skin care is never as simple as one hero ingredient; this serum would've been better if it had contained a range of antioxidants and perhaps a skin-repairing or cell-communicating ingredient or two. A cocktail of anti-aging ingredients beats a high amount of any one ingredient!

This serum's other claim to fame is the growth factor it contains, listed as TGF-beta-1. The "TGF" stands for "transforming growth factor," and this ingredient is not without risks, which we discuss in the More Info section. The inclusion of this growth factor is why we rated this serum average.

  • Fragrance-free.
  • Contains an impressive amount of vitamin C.
  • Very silky texture.
  • Expensive.
  • Formula lacks a range of beneficial ingredients.
  • The growth factor this contains is controversial.
More Info:

There are many growth factors the body uses in key amounts, in key sequences, and at key times. Growth factors, including the TGF-beta-1 this serum contains, are proteins that affect how cells grow and differentiate. They are present and at work throughout the body, but not much is known about their efficacy when applied topically, which is the case with this product. In the skin, TGF-beta-1 stimulates collagen remodeling and encourages wound healing.

The risk with growth factors is that they could accelerate the growth of skin cancer by stimulating the overproduction of skin cells. In the case of TGF, which stimulates collagen production, it can encourage scarring because scars are the result of excessive collagen production, and if you make too much collagen you get a scar or a knot on the skin such as a keloid scar. Most of the research on the issue of growth factors for skin has looked primarily at wound healing, and at short-term use of key growth factors. In skin-care products, however, they would be used repeatedly, and possibly over long periods of time—we just don't know for certain how risky that may be.

According to the 2009 textbook Cosmetic Dermatology, Second Edition, "Whether the TGF-B [Beta] and other growth factors contained in cosmeceuticals are stable, can be absorbed adequately, or exert a functionally significant outcome to induce dermal remodeling and reverse photoaging is unclear since well-controlled studies are lacking." To date, we could not find any recent studies proving the efficacy or safety of topically applied growth factors.


A true skin care breakthrough! Topix has combined proven, stable L-ascorbic acid serum with the liposome encapsulated Growth Factor TGF- beta-1 to create the hottest product in anti-aging skin care. Research suggests that TGF- Beta-1 can play a significant role in stimulating collagen growth and strong tissue structure, resulting in healthier, younger-looking skin.


Cyclomethicone, L-Ascorbic Acid, Silicone Polymer, Dimethicone, Purified Water, Dimethicone Copolyol, Phospholipids, TGF-Beta-1, Cimicifuga Racemosa Extract.

Brand Overview

Topix At-A-Glance

Strengths: Most of the products are fragrance-free; packaging keeps light- and air-sensitive ingredients stable during use; several good products with retinol in varying strengths; good moisturizers and cleansers; very good body lotions.

Weaknesses: Expensive; the physician allure may seem enticing, but these products do not require a doctor's visit or medical supervision; no AHA or BHA exfoliants; no viable skin-lightening options; fragrant toner; the growth factors in the Citrix serums are potentially risky ingredients.

Topix is best known for its two chief skin-care brands, Replenix and Citrix. Of the two, we're asked most often about the Replenix collection; the Citrix line is smaller and focused on anti-aging products with vitamin C. The Replenix products contain a broader range of anti-aging ingredients, such as retinol, green tea, and grape-derived resveratrol, and the claims are broader, too—so little surprise that the Replenix products appeal to more people concerned with signs of aging. Both Replenix and Citrix offer fragrance-free formulas, albeit at fairly high prices, which is typical of most physician-dispensed lines.

A chief selling point of Topix is its physician-dispensed angle, which gives the products a medical élan; in truth, however, not a single ingredient in these products is "medicinal," prescription, or exclusive to physician-sold products. That is, you don't need to see a doctor to be "prescribed" Topix products; rather, they can be obtained from several websites, no appointment necessary. The big question is whether or not you should add any Topix products to your shopping cart—and the answer is "it depends."

Within the Replenix line, the most interesting products include the serums and moisturizers. Although none of them are superior to the best options available, most of them do offer good (though pricey) formulas that treat skin to a range of beneficial ingredients.

If you're keen on retinol (and it's a great anti-aging ingredient), Replenix has you covered with several serums offering different strengths of retinol. The various strengths allow you to "step up" to stronger retinol products once your skin has acclimated to the lower strengths. Although that sounds intriguing, it's not really necessary. As we explain in the reviews, more retinol is not necessarily better, and some may find the higher-strength retinol products too sensitizing, so caution is warranted. Indeed, some people cannot tolerate any amount of retinol!

The Citrix products aren't all that exciting unless you want vitamin C in every product. Although there's nothing wrong with vitamin C, it's a mistaken notion to focus on one hero ingredient because skin requires a variety of beneficial ingredients to look and act younger. Topix also adds growth factors to their Citrix serums, but these growth-factor ingredients are unproven for topical use and may present risks (we explain why in the reviews). In short, Citrix isn't all that exciting, and several of these products fall short in one way or another.

Our research revealed that Topix has some intriguing products, but, with few exceptions, there is nothing that you cannot find elsewhere for less money. It's important to let go of the notion that skin-care products sold at a doctor's office are superior to those sold elsewhere. The truth is: There are good and bad products in every retail outlet—knowing what you're buying is more important than where you're buying it or who's selling it!

For more information about Topix, call (800) 445-2595 or visit www.topixpharm.com.

About the Experts

The new Beautypedia Team proudly and unequivocally maintains the commitment to help you find the best products possible for your skin. We do this by relentlessly pursuing and relying on published scientific research so you will have unbiased information on what works and what doesn't-and the sneaky ways you could be making your skin worse, not better!

The Beautypedia Team reviews all products using the same research, criteria, and objectivity, whether the product being reviewed is from Paula's Choice or another brand.

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Correct ingredients list

The reason of this message is to let you know the correct ingredients list of the product: Cyclomethicone, L-Ascorbic Acid, Dimethicone Crosspolymer, Polysilicone-11, Silicone Polymer, Squalane, PEG/PPG-18/18 Dimethicone, Phospholipids, TGF-Beta-1, Cimicifuga Racemosa Root Extract. This product does NOT contain water, thanks to this ascorbic acid is stable, also Squalane addition is worth to underline. TGF is closed in liposomes. A big pros of this product is stable formula.

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