What is sensitive skin? As a dermatologist, I am not sure; however, the concept resonates well with consumers. For 30 years, to fill my research panels, I have been asking people if they have sensitive skin. The responses I receive are quite interesting.
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What is sensitive skin? As a dermatologist, I am not sure; however, the concept resonates well with consumers. For 30 years, to fill my research panels, I have been asking people if they have sensitive skin. The responses I receive are quite interesting.
Those who consider themselves as sensitive or emotional individuals relate these traits to having sensitive skin, although I am not sure that the two are correlated. Others state they are sensitive to many substances, such as gluten or shellfish or peanuts, and therefore consider themselves to have sensitive skin. Here again, I am not sure that food allergies correlate with sensitive skin.
Still others state they experience stinging, burning and itching with a variety of skin care products and therefore consider themselves to have sensitive skin. In my view, these people may indeed have sensitive skin but there are other attributes that also require consideration.
This article explores the basic characteristics of, certified products for and perceptions of sensitive skin, among others. It also outlines formulation considerations for this growing market.
Characteristics of Sensitive Skin
In my mind, sensitive skin embodies three skin attributes: skin barrier issues, vasomotor instability and heightened neurosensory awareness.
Skin barrier issues: The stratum corneum skin barrier must be intact to prevent externally applied substances, ranging from cleansers to moisturizers, from inadvertently penetrating the skin. This means the protein-rich corneocytes must be held tightly in place by the ceramide-rich intercellular lipids. Damage to the protein structure of the corneocytes, which may occur with high-pH cleansers or defective intercellular lipids – such as those found in eczema and dry skin – may cause skin barrier defects resulting in sensitive skin.
Vasomotor instability: Vasomotor instability is found in people who flush or blush with minimal cutaneous stimuli. For example, these individuals may apply a menthol-containing aftershave to the face, which results in vasodilation, causing a red face. This type of sensitive skin is found in people with rosacea, who experience flushing with skin sensates, rapid temperature changes, caffeine ingestion and red wine consumption.
Heightened neurosensory awareness: Lastly, heightened neurosensory awareness occurs in individuals who seem to experience stinging, itching, tingling and burning with the application of a variety of topical products to the face. These people come to my office carrying a bucket of skin care products claiming all the products cause problems.
If no allergic or irritant contact dermatitis triggers can be identified, these people are said to have cosmetic intolerance syndrome – which is a nice medical catchall term that means nothing and simply conveys that these people have trouble with many topical formulations.
Defining Sensitive Skin
At present, there is no official definition for sensitive skin, it is purely a marketing claim without scientific meaning. Several years ago, a convention of thought leader dermatologists was convened to write a definition for sensitive skin, but at the end of the two-day meeting, no consensus was reached and the project was abandoned.
This makes sensitive skin a perfect marketing term since no one can seriously challenge related product claims. It is a phrase that defies definition, yet consumers know exactly what it means to them individually.
Certified Products for Sensitive Skin
Several consumer dermatology action groups have attempted to provide guidelines for disease subsets that may experience sensitive skin issues. For example, the National Eczema Association and the National Rosacea Society have developed seals of approval to help consumers identify products that have undergone testing to meet guidelines appropriate for sensitive skin.
Eczema is a condition characterized by barrier defects, which is one of the three physiologic attributes of sensitive skin discussed earlier. Rosacea, however, is a condition characterized by all three physiologic attributes of sensitive skin – barrier defects, vasomotor instability and heightened neurosensory awareness.
With rosacea, barrier defects may in part be due to the inflammatory component of the disease from over-reactive immunity or mite infection, whereas vasomotor instability is embodied by the red flushed cheeks immediately diagnostic of rosacea. The neurosensory component is exhibited by the frequent facial stinging, itching and burning these individuals experience.
The National Rosacea Society seal was newly introduced this year (2023) to back claims related to sensitive skin with reputable science. Indeed, since rosacea wholly embodies the dermatologic attributes of sensitive skin, rosacea patients are usually included in any sensitive skin testing panel.
Consumer Perceptions of Sensitive Skin
As might be expected, consumer perceptions of sensitive skin may differ from dermatologist perceptions. For example, consumers frequently consider acne breakouts after product use to be a manifestation of sensitive skin, whereas to the dermatologist, these breakouts would fall under acnegenic or comedogenic conditions – and respective non-acnegenic and non-comedogenic product solutions.
Consumers may also consider allergic reactions to fall under sensitive skin, but the dermatologist would consider them irritant contact dermatitis, due to an ingredient causing skin barrier damage, or allergic contact dermatitis, due to an ingredient allergy that causes facial swelling and inflammation – which would relate to a hypoallergenic product solution.
Some might even consider lumping the claims non-acnegenic and hypoallergenic under the sensitive skin claim. However, consumers respond positively to all three claims and may be more encouraged to purchase a product that delivers on greater rather than fewer claims.
Dermatologic Perceptions and Considerations
Dermatologists view sensitive skin as characteristic of all skin diseases. Common conditions that embody sensitive skin include eczema, atopic dermatitis, seborrheic dermatitis, rosacea, cosmetic intolerance syndrome and psoriasis. Some of these are specific to the face, e.g., rosacea and cosmetic intolerance syndrome; some are conditions of the scalp, including seborrheic dermatitis; and others can involve the scalp, face and body, such as atopic dermatitis and eczema. Therefore, products designed for sensitive skin must be appropriate for all body areas.
It is important to note that many skin care products are used in conjunction with prescription products during the treatment phase, then used alone to avoid disease recurrence during the maintenance phase. This means that sensitive skin-labeled products must not cause problems if minimal penetration into the skin occurs.
Products must also create an environment for optimal skin healing to allow skin barrier issues contributing to sensitive skin to be resolved. While many formulators look at products for sensitive skin from the standpoint of not causing problems, the dermatologist looks at sensitive skin products for their potential to minimize sensitive skin issues.
9 Tips for Formulating Sensitive Skin Care
Formulating for sensitive skin can be challenging, since there is no agreed upon definition. However, following are my opinions, as a dermatologist, regarding how sensitive skin formulas might be approached based on nine key concepts.
1. Less is more: Fewer ingredients are better than more ingredients. Many individuals with sensitive skin may demonstrate irritant or allergic contact dermatitis to a variety of ingredients; therefore, it is less problematic to use simpler formulations with fewer ingredients.
Furthermore, many cosmeceutical and moisturizer formulations are characterized by a complex cocktail of botanical extracts, which can cause allergic contact dermatitis. A diagnosis of which plant-derived material is causing the problem is also challenging since plant materials are composed of many different constituents.
As such, basic formulations with justifications for the purpose of every ingredient work better in sensitive skin populations. Ingredients that are added for market distinction or enhanced aesthetics should be considered carefully.
2. Avoid sensates: Sensates are substances that produce a feeling immediately upon contact with the skin. One of the most popular sensates is menthol, which is commonly used by dermatologists in moisturizers to minimize the sensation of itch. The cooling sensation produced by the menthol distracts the brain from the itch sensation, especially when the menthol moisturizer is placed in the refrigerator.
However, many people with sensitive skin will experience extreme burning and even mild pain when menthol is placed on the skin. This diversity in menthol response is intriguing, as it identifies different nerve firing actions and perceptions of feeling that may be physiological components of sensitive skin. In general, however, sensates should be avoided in sensitive skin formulations.
3. Avoid vehicles that rapidly evaporate upon skin contact: Another sensory issue with sensitive skin is the rapid evaporation of materials from the skin surface. While this evokes a pleasant sensation of cooling for many people, individuals with sensitive skin may find it annoying. Furthermore, the rapid evaporation of materials from the skin may evoke flushing and blushing in persons with rosacea.
Many substances that rapidly evaporate from the skin are light-weight alcohols, such as isopropyl alcohol or ethanol, sometimes used in toners and after-shave preparations. These types of formulations are generally not appropriate for sensitive skin.
4. Eliminate common allergens and irritants: It goes without saying that common allergens and irritants should be eliminated from sensitive skin formulations. However, the problem lies in identifying them. Irritants include anything that destroys the skin barrier, removes the intercellular lipids and denatures the proteins. Such ingredients include glycolic acid, lactic acid, urea, etc.
Avoiding allergens is a little more difficult. The American Contact Dermatitis Society identifies an allergen of the year each year – see Militello, et al., for a review from 2000 to 20201 – and it might be worthwhile to review this list. For example, in 2023, lanolin was named; in 2022, it was aluminum and for 2021, it was acetophenone azine (AA). Avoiding all the identified allergens is challenging, though, because in time, you run out of allergens to identify.
There is also the list of ingredients in dermatologists’ standard patch tests, including PPD, lanolin alcohol, parabens, fragrance mixes, formaldehyde, isothiazolinone, quaternium-15 and others.2 A quick look at this list might be helpful – although some ingredients are being phased out of cosmetic formulations.
5. Include occlusive agents to decrease transepidermal water loss: The main physiologic commonality in sensitive skin is increased transepidermal water loss from the skin to surrounding low humidity environments. This loss is continual, which is one reason individuals must consume water daily. All humans lose water to the environment, but this loss is accelerated if the skin is unhealthy – and this may be the case in sensitive skin.
Occlusive hydrophobic ingredients will provide a barrier to water evaporation. This will create an optimal environment for barrier repair and healing will be initiated with an outburst of ceramide production. Valuable ingredients to reduce transepidermal water loss include petrolatum, shea butter, dimethicone, mineral oil, vegetable oils, etc.
6. Formulate at a slightly acidic pH: One of the characteristics of healthy skin is the presence of what is known as the acid mantle. This entity is so-named because healthy skin has a pH of somewhere between 5.2 and 5.4. This slightly acidic pH prevents the growth of disease-causing Staph aureus and other pathogenic bacteria.
Raising the pH can result in not only skin disease, but also the swelling of the stratum corneum corneocytes. This permits products designed for leave-on applications to penetrate the skin. Therefore, products designed for sensitive skin should maintain the natural skin pH.
7. Ensure ingredient purity: Ingredient purity is essential for sensitive skin formulations. For example, contamination of raw pigment materials with nickel, the most common metal allergen, must be avoided. Most companies have rigid guidelines for raw material suppliers to meet, and even perform in-house testing on ingredient batches to insure purity. This is essential.
8. Carefully construct emulsifier systems: Oil-in-water emulsions are the most common in the skin care industry, but emulsifiers can also emulsify skin’s intercellular lipids. This is a problem in sensitive skin, where the barrier may already be compromised. The emulsifier cannot distinguish between the lipids in the product and the lipids on and around the corneocytes. Carefully constructed emulsifier systems can therefore prevent further damage to the skin barrier and the worsening of sensitive skin.
9. Avoid exfoliants: Lastly, exfoliants should be avoided as they can damage the fragile skin barrier in those afflicted by sensitive skin. Exfoliation is the act of removing corneocytes from the surface of the stratum corneum, either mechanically or chemically. Mechanical methods include rough scrubbing implements, particle-containing scrubs and rough-edged devices, among others. Chemical methods include exposure to acids, such as glycolic or malic, that disrupt the ionic bonds between the skin cells, inducing premature sloughing. While exfoliation is thought to improve the smoothness and radiance of aging skin, it can also damage the skin barrier if pursued too aggressively or too frequently in sensitive skin.
Future Directions for Sensitive Skin Formulating
This article has focused on ways to minimize skin care product-induced damage to sensitive skin. However, sensitive skin products of the future should not only avoid provoking sensitive skin, but also promote the resolution of sensitive skin. This can be accomplished by decreasing skin inflammation, which is a final common pathway that leads to sensitive skin.
Many sensitive skin formulations include ingredients such as allantoin, green tea polyphenols or chamomile extracts such as bisabolol to function as anti-inflammatory agents. Many antioxidant botanicals also possess anti-inflammatory qualities that may be helpful when designing products for sensitive skin. It is my hope this article has helped to decipher the complex world of sensitive skin and formulating for such.
References
1. Militello, M., Hu, S., Laughter, M. and Dunnick, C.A. (2020, Apr 25). American Contact Dermatitis Society allergens of the year 2000 to 2020. Dermatol Clin. Available at https://pubmed.ncbi.nlm.nih.gov/32475509/
2. Oakley, A. (2008). Baseline series of patch test allergens. DermNet. Available at https://dermnetnz.org/topics/baseline-series-of-patch-test-allergens
