Cosmeceutical Skin Reactions - Common Culprits Revealed

The sun rises, you open your eyes, let out a big yawn, and finally decide to get out of bed. Your day has started. Breakfast is consumed… or not (but hopefully has been). E‑mails and social media feeds are all checked. Now it’s finally time to “get ready.” Ladies, before you step out the door, through to the time you go back to sleep, you are estimated to use 12 personal‑care products, containing over 180 ingredients. For the men, you are estimated at 6 personal‑care products containing roughly 85 ingredients.[1]

Whether they be cosmetics, deodorant, lipstick, cleansers, hair products, or sunscreen, we are often in the crosshairs of ingredients which have the potential to cause an itch, sting, or redness… and sometimes even worse reactions. Generally, the two most common forms of skin reaction to personal‑care products include allergic contact dermatitis and irritant contact dermatitis. The allergic form is essentially an immune system–based reaction to an ingredient, leading to the symptoms of skin inflammation. It is less common than the irritant form, which does not involve the immune system mounting a reaction, but rather is a nonspecific skin reaction to a given irritant ingredient. The ability of a biochemical to act as an irritant depends on its chemical size, concentration, and how long our skin is exposed to it, among other factors.[2]

One of the challenges in this area is that trying to estimate how often contact skin reactions occur is hampered by the fact that people who experience such reactions usually (and understandably) stop using the problematic product, thus never get a chance, or feel the need, to report the reaction to their physician.[3] It is often those hard‑to‑determine‑the‑culprit cases which make their way to the dermatologist’s office.

We are going to focus our discussion today on some of the most common culprit ingredients and ingredient categories which have been documented in causing either allergic and/or irritant forms of skin reactions. Some of the ingredients discussed are popular and frequently used components in cosmeceutical products. The point is not to say that these ingredients must be avoided, but rather to highlight that in some individuals, these ingredients have been determined to be a likely and/or definitive cause of their skin irritation or allergic reaction. If you are experiencing any symptoms such as redness, itching, stinging, or scaling, and are unsure of its cause, these ingredients discussed may help provide some direction in identifying—and avoiding—that (literal) source of irritation. As always, please first review and discuss these symptoms and product usage with your dermatologist and skin health–care providers.

Dispelling the Concept of “Hypoallergenic”

In the world of cosmetics and cosmeceuticals, there can be numerous terms thrown around which aren’t as they seem. The term “hypoallergenic” is a good example: It is often wrongfully assumed that hypoallergenic is synonymous with nonallergenic, which it is not. It signifies a reduced allergic potential, but not a zero allergic potential. In general, and to its credit, a hypoallergenic cosmetic should not contain those ingredients which are most often considered problematic; additionally, prior to going to market, it has hopefully been tested for its allergic/irritant potential, especially on individuals known to have sensitive skin. However, these factors cannot always be assumed, plus there may be a sensitivity to other ingredients in the product not traditionally known to be problematic.[4]

Common Culprit Categories and Ingredients

Fragrances
Fragrances are considered one of the most common causes of allergic‑contact skin inflammation. Over 2,500 fragrance ingredients are used in cosmetic/cosmeceutical products. Your dermatologist can test allergenicity to various fragrance ingredients, often in the form of set mixtures of the most popular culprits. However, as more ingredients get introduced into the cosmetic realm, these mixtures tend to also continually evolve in what they test for.  Confusing things even more, not all specific ingredients which comprise a fragrance need to be listed on the label. In addition, even if a product is labeled as “unscented,” it does not necessarily mean fragrance‑free, only that it cannot be smelled. Often, fragrance ingredients are used to mask the odour of other ingredients in the formula, leading to a lack of smell despite the presence of fragrance ingredients. Finally, a “fragrance‑free” product may still contain fragrance ingredients if they serve another function in the formula, such as being a preservative. Herbal ingredients, which can still be a source of irritancy or allergy, can also find their way into a fragrance‑free product for their topical medicinal benefit, even though they also impart a fragrance/scent to the whole formula.[1]

Preservatives
These comprise the second‑most‑common source of cosmetic allergens and include antimicrobials, antioxidants, and UV‑light absorbers. As you can imagine, these work to prevent product contamination. In relation to cosmeceuticals, one of the preservatives more frequently found to cause allergic contact dermatitis is quaternium‑15. In addition, DMDM hydantoin, diazolidinyl urea, and 2‑bromo‑2‑nitropropane‑1,3‑diol have all been found to be common allergens.[1] Likely the most debated preservative on the market is that of parabens (para‑hydroxybenzoic acid in its various chemical forms). In addition to their use in cosmetics and personal‑care products, they are also found in pharmaceuticals and used as food additives. In relation to the question regarding parabens as culprits for allergic‑contact dermatitis, the likelihood is low, especially when used in the lower concentrations found in most cosmetic products. However, the opposite may be true as the level increases, such as in certain topical therapeutic medications, and especially if applied over damaged/sensitive skin.[5][6] Where things get a little murky is in the concern over the effect of parabens as hormone disruptors. Although believed to pose low risk, owing to both their weak estrogenic activity and having been shown in studies to pose negligible concern when used at recommended doses, some researchers have highlighted further areas of exploration. Namely, they indicate how much of the research on parabens was done on individual parabens, which calls into question the additive and cumulative effect of exposure to all the various paraben chemical forms, from all of its many sources found in our society.[7] Like many popular debates in medicine, this one will likely continue for some time.

Vitamins

The next few sections may be surprising to some, but many of the very ingredients one may purchase a cosmeceutical for can ironically be the cause for skin irritation. In the realm of vitamins added to topical formulations, here are a few which have, for some, been shown to trigger skin irritation and, more rarely, allergy.

Vitamin A: Those using vitamin A in any of its forms (retinol, retinaldehyde, retinyl palmitate, etc.) may have already experienced its irritant, reddening, and skin‑drying effects. This is expected, however, and is sometimes referred to as the “retinization” of the skin. For this reason, your skin‑care provider may recommend certain approaches to minimizing this effect when starting on vitamin A therapy. These can include starting with a low concentration (e.g. 0.25% retinol) and gradually increasing the dosage with each new tube of product; applying retinol after applying moisturizer for about one month, then switch to applying it before the moisturizer; and using a small amount at night every third day for about two weeks, then gradually increasing usage frequency over the course of several weeks thereafter.[8]
Vitamin C: Owing to the low‑pH effects of ascorbic acid on the skin, some have experienced irritation. Fortunately, the cosmetics industry has been able to formulate versions of vitamin C, such as ascorbyl phosphate, which mitigate that low‑pH effect, making it a more tolerable form for those with sensitive and irritation‑prone skin.[9]
Vitamin E: Although irritant and allergic contact dermatitis have been reported for topical vitamin E, it is mentioned here as a cautionary example for topical self‑care. Many of the reports for allergic reactions seem to be related to cases where individuals cracked open a vitamin E oil capsule intended for oral use, and instead applied it to their skin. By contrast, cosmeceutical‑grade vitamin E, which has been formulated for skin use, is typically rarely allergenic. This highlights the importance of using products only for their intended method of use.[1]

Herbs

With the incredible growth in popularity and usage of botanical (herbal) ingredients and products comes an equal degree of commonly held conceptions that need to be dispelled. First is the notion that botanical cosmeceutical ingredients are “natural,” and therefore better or safer than a “chemical” or “synthetic” ingredient. If the skin is to react to a chemical, then the skin will react with said chemical; it doesn’t care where it came from—Mother Nature or a laboratory. For example, to say that botanical fragrances, organic or not, are hypoallergenic is a mute claim since, as we discussed earlier, hypoallergenic does not mean nonallergenic. In the individual with sensitive skin, even hypoallergenic products can be a source of irritation. In addition, although many herbal ingredients were first discovered and obtained from plant sources, many cosmeceutical companies will not continue to source them from plants due to cost prohibition and challenges with how the original extracts can affect the formula (e.g. in product colour, texture, etc.). As such, many extracts are modified and synthesized into a form which better incorporates and biochemically “work” with the other ingredients in a cosmetic product.[4] Some of the common herbal extracts which have been documented for triggering allergic contact reactions include tea tree oil, witch hazel, curcumin, aloe, peppermint, and hydrolyzed wheat protein, a protein derivative found in cosmetic creams and hair‑ care products.[1][10]

Hydroxy Acids

Hydroxy acids represent a group of cosmetic compounds often used for skin exfoliation, improving skin texture or skin barrier function, and to reduce the appearance of skin aging.[11][12] The main types of hydroxy acids are alpha‑hydroxy acids (such as glycolic acid, lactic acid, and citric acid), beta‑hydroxy acids (such as salicylic acid), and poly‑ hydroxy acids (such as gluconic acid and lactobionic acid).[12] Hydroxy acids can be a cause of irritant reactions as well, including stinging and burning sensations. In general, most irritant reactions are seen with the alpha‑hydroxy acids, owing to their low pH and smaller chemical size, allowing them to better penetrate the skin and irritate nerve endings. An impaired skin barrier, however, can increase the irritation potential for both beta‑hydroxy acids and poly‑hydroxy acids, which normally do not penetrate the upper skin layer as efficiently as do the alpha forms.[1]

What You Can Do to Mitigate Skin Reactions

The Starting Point: The obvious starting point depends on how easy it is to suspect and identify an irritating ingredient. The newly tried deodorant brand which produces a rash under the arms is an easy determination. However, in many cases the answer isn’t that obvious. As such, a great place to start would be with a dermatologist or allergy specialist, who can help establish a diagnosis between irritant and allergic‑contact dermatitis, or any other skin concern, while also providing a patch test to help narrow down and pinpoint the offending cosmetic ingredient(s). Avoidance of all products containing these offending ingredients is then key.

Build and Chart Your Cosmetic History: Ahead of working with your health‑care provider, keeping a detailed diary of products used and how/when they relate to irritation development can be helpful. For example, a formaldehyde‑based preservative may be suspected if one’s diary log shows a rash development each time they use a hair‑straightening product, nail polish, or mascara.[8]

Reduce Overall Exposure: While it may be socially hard to avoid certain cosmetics, like deodorants, we may not necessarily need other products. For example, in many cases, optimal skin health is not predicated on the use of a cabinet full of skin‑care products. Working with your skin health–care provider can help you achieve a “less‑ is‑more” approach in determining the lowest number of cosmeceuticals you need. In naturopathic aesthetics, in addition to cosmeceutical support, the use of dietary adjustments, oral supplements, and even acupuncture can help achieve healthy skin and further reduce one’s reliance on a multitude of products. To also help reduce exposure, look to choose products which contain as few ingredients as possible.[8]

Avoid the Blind Use of Hypoallergenic Products: As discussed earlier, hypoallergenic does not mean nonallergenic. However, it can still provide an option which reduces the overall likelihood of the product containing some of the more common allergenic culprit ingredients. Do your due diligence in exploring if the cosmeceutical company behind a given hypoallergenic product has in fact tested their final product on human subjects with known skin sensitivity. Additionally, you can inquire if the company has performed repeated‑insult patch‑testing of their product as part of their safety evaluation.[4]

Strengthen that Skin Barrier: More and more research has shown that skin sensitivity and allergic potential both increase when the skin barrier is compromised. As discussed at length in my previous articles on Naturopathic Currents, the barrier locks moisture in the upper skin layers as well as protects it from unnecessary exposure to most of what the skin encounters each day. A damaged barrier is an open barrier, ripe for ingredients like the beta‑ and poly‑hydroxy acids, discussed above, to impart irritation where they typically would not have been able to.[8] Therefore, barrier‑strengthening moisturizers/ cleansers rich in ceramides and other barrier lipids, along with the other topical, lifestyle, and dietary approaches I’ve discussed previously, all come together to offer an often‑overlooked method of minimizing the potential for developing a skin irritation.