'Winter dry skin' is dry skin that develops during the cold winter season.
To prevent winter dry skin, you must protect your skin barrier, including your moisture barrier, lipid barrier and acid mantle.
This article will discuss:
- What is dry skin?
- What is very dry skin?
- What is winter dry skin?
- What causes winter dry skin?
- What is the skin barrier?
- What is the moisture barrier?
- What is the lipid barrier?
- What is the acid mantle?
- How to prevent winter dry skin?
- How to protect your moisture barrier
- How to protect your lipid barrier
- How to protect your acid mantle
- Summary
- References
What is dry skin?
Dry skin is skin that is lacking water, humectants and fats.
Humectants absorb and hold water, while fats coat the skin and seal in moisture.
When there is not enough water, humectants or fats, skin barrier disruption can occur, further worsening symptoms of dry skin.
The following contribute to dry skin:
- lack of water in skin
- lack of water-holding substances called humectants (glycerin, hyaluronic acid, natural moisturizing factors)
- lack of epidermal lipids (ceramides, fatty acids, cholesterol)
- lack of sebum (triglycerides, wax esters, squalene)
Symptoms of dry skin include:
- Loss of skin elasticity.
- Skin feels tight, dehydrated.
- Skin appears dull, rough and blotchy.
- Slight to severe flaking, scaling or peeling.
- Fine lines and wrinkles are more pronounced.
- May have irritation and a burning sensation.
- May have itching.
Dry skin is very common and can occur for a variety of reasons.
Anyone can develop dry skin.
Read more: What is Dry Skin?
Dry skin is often relieved with the use of moisturizers, a good face oil, and some lifestyle modifications, such as using a humidifier, avoiding harsh cleansers, and supplementing the diet with essential fatty acids.
What is very dry skin?
Very dry skin is a more severe type of dry skin, and is characterized by skin barrier damage, microbe imbalances and inflammation, leading to red, irritated, itchy skin.
Very dry skin symptoms include:
- skin feels tight and dehydrated, especially after showering, bathing or swimming
- skin appears dull, rough and blotchy
- slight to severe flaking, scaling or peeling
- fine lines and wrinkles are more pronounced
- irritation and itching (pruritus)
- inflammation and redness
- deep cracks on hands and feet that may bleed
- associated with skin conditions such as eczema and psoriasis
Very dry skin usually has underlying genetic components as well as environmental factors that play a role.
Very dry skin does not typically respond to just moisturizers.
Nutrient-rich oils, balms and barrier creams are required to improve very dry skin and protect against further damage.
Active ingredients, including vitamins, humectants, ceramides, fatty acids and cholesterol can help repair the skin barrier, calm redness, and sooth irritation and itch.
Some people with very dry skin may also require medications to control symptoms, including antimicrobial agents, antihistamines, anti-inflammatory agents, immunotherapy, biologicals, phototherapy, and others.
Read more: What is Very Dry Skin?
What is winter dry skin?
'Winter dry skin' is dry skin that develops during the cold winter season.
Winter dry skin can have a wide spectrum of symptoms - from mild dryness and flaking to severe itching, redness and pain.
Winter dry skin symptoms are painful and frustrating, and often associated with skin conditions such as eczema or atopic dermatitis.
Learn more: What is Dry Skin Pain?
Symptoms of winter dry skin depend on the severity of damage to the skin barrier.
For instance, mildly dry skin, or dehydrated skin is due to a lack of water and water-holding substances (humectants) in the moisture barrier.
Dry skin is due to a lack of water, humectants and lipids/fats in the skin barrier.
Very dry skin is similar to dry skin, but also suffers from redness and inflammation.
Winter dry skin symptoms can range from dehydrated skin to dry skin to very dry skin:
Exposure to winter weather can weaken your skin barrier and its protective functions.
Winter dry skin has been reported to involve scaling, defects in water holding and barrier functions, and decreased lipid levels in the stratum corneum (Ishikawa et al, 2013).
Learn more: Winter Dry Skin - What is it?
What causes winter dry skin?
It is broadly accepted that skin barrier functions may be negatively affected by winter conditions (reviewed by Engebretsen et al, 2016), including:
- cold temperature
- low humidity
- wind exposure
- sun exposure
Cold to freezing temperatures can damage your skin. Furthermore, cold temperatures often mean low humidity, which also dries out your skin. Bitterly cold winds can also strip moisture from exposed skin. And during the winter there is also potential for UV damage from sun exposure.
Cold temperatures, low humidity, wind and sunlight exposure can dry your skin and damage your skin barrier.
Learn more: Winter Dry Skin - What causes it?
What is the skin barrier?
Your skin barrier includes the outermost layers of skin, called the stratum corneum.
The stratum corneum can be thought of as a brick wall that protects you.
On a weight basis, the stratum corneum contains approximately 70% protein, 15-25% water and 15% lipids (Ananthapadmanabhan et al, 2013).
The structure of the stratum corneum can be described as a ‘brick and mortar’ model, in which the protein-rich corneocytes are the bricks, and the mortar is the lipid‐rich matrix containing ceramides, cholesterol, and fatty acids.
When your skin barrier is healthy, it feels and appears smooth, soft, and plump.
In contrast, a damaged skin barrier looks dry, rough, dull, and dehydrated, and may become irritated and inflamed.
Learn More: What is The Skin Barrier
The skin barrier includes:
- The moisture barrier
- The lipid barrier
- The acid mantle
What is the moisture barrier?
The skin moisture barrier is a part of your skin barrier.
The skin moisture barrier ensures your skin is hydrated by trapping and holding water into your skin.
The skin moisture barrier is composed of water, natural moisturizing factors (NMFs) and other humectants, such as glycerol and hyaluronic acid to attract and hold onto moisture.
Normal skin hydration
Water is essential for the normal functioning of the skin.
The water content of skin is remarkably high - the epidermis (the outer skin layer) contains more than 70% water, while its outermost layer, the stratum corneum has been shown to contain ~15 - 25% water (Warner et al, 1988; Caspers et al, 2001; Caspers et al, 2003).
- it maintains plasticity of the skin, protecting it from damage
- it contributes to optimum stratum corneum barrier function
- it allows hydrolytic enzymes to function in the process of desquamation
When the water content of the stratum corneum falls below 10%, scaling on the skin surface becomes visible (Rycroft, 1985).
The retention of water in the skin is dependent on:
- Natural moisturizing factors (NMFs) and other humectants (such as glycerol and hyaluronic acid) to attract and hold onto moisture
- Intercellular lipids (fats) that form a barrier to prevent transepidermal water loss (TEWL) (Verdier-Sévrain et al, 2007).
Water and skin cell turnover
Desquamation is the natural process of shedding skin cells.
New skin cells are formed at the base layer of the skin, and they differentiate and migrate towards the skin surface, in a process that takes approximately 4 weeks. Nearly a billion cells are lost each day from the surface of adult skin (Milstone et al, 2004).
One of the critical functions of water in the skin is to participate in hydrolytic enzymatic processes required for normal desquamation.
In other words - water is necessary for the enzymes to function properly.
If the skin water content falls below a critical level, the enzymatic function required for normal desquamation is impaired, leading to skin cells sticking and building up on the skin surface (Verdier-Sévrain et al, 2007).
These changes lead to the visible appearance of dryness, roughness, scaling, and flaking (Verdier-Sévrain et al, 2007).
Learn more: What is Dehydrated Skin?
What is the lipid barrier?
The lipid barrier is a part of the skin barrier.
The surface of your skin is covered by a layer of protective fats, including epidermal lipids and sebum.
Epidermal lipids include:
- Ceramides
- Free Fatty Acids
- Cholesterol
Epidermal lipids are released from keratinocytes (skin cells), and are a mixture of ceramides, free fatty acids and cholesterol. These lipids are released from skin cells and fill the spaces between the cells, like mortar or cement (Pappas, 2009).
Sebum is made of:
- Triglycerides
- Wax esters
- Squalene
Sebum is an oily, waxy substance produced by your body’s sebaceous glands and eventually released to the surface of the skin. Sebum is primarily made up of non-polar lipids as triglycerides, wax esters and squalene. Sebum coats the skin, seals in moisture, and protects your skin from getting too dry (Pappas, 2009).
Beneficial fats and lipids help to lubricate and coat your skin cells and nourish your skin.
Learn more: Lipid Barrier - Beneficial Fats in The Skin Barrier
What is the acid mantle?
The term "acid mantle" describes the inherent acidic nature of the outer skin barrier, or stratum corneum.
Maintaining skin pH is important, as skin pH influences skin barrier homeostasis, stratum corneum integrity and cohesion, and antimicrobial defense mechanisms.
Many factors can affect the pH of the skin, including age, sebum, sweat, detergents, cosmetics, and irritation.
Learn more: What is The Acid Mantle of The Skin Barrier?
How to prevent winter dry skin?
Winter dry skin can be caused by cold temperatures, low humidity, harsh winds and sun exposure.
These factors can damage your skin barrier, including your moisture barrier and lipid barrier.
The key to preventing winter dry skin is to protect your skin barrier.
How to protect your moisture barrier
The skin moisture barrier is composed of water, natural moisturizing factors (NMFs) and other humectants, such as glycerol and hyaluronic acid to attract and hold onto moisture.
There are several ways to protect your moisture barrier:
- Drink water
- Use a humidifier
- Use a moisturizer with humectants
- Limit exposure to cold weather
- Protect your skin from the elements
1. Drink water
Water is involved in virtually all bodily functions.
Thus, ensuring that the body has enough water to maintain proper function is important for health.
Drinking water can increase your skin hydration, especially if you have a low water intake.
Drinking an additional 2 L of daily water over 30 days showed an increase in both stratum corneum hydration and “deep” skin hydration, particularly when the individual’s regular diet included low amounts of water (Palma et al, 2012; Palma et al, 2015a; Palma et al, 2015b).
Another experimental study reported a slight increase in stratum corneum hydration after an additional dietary water intake of 1 L per day for a period of 42 days (Mac-Mary et al, 2006).
For hydrated skin, it is best to aim for 6 - 8 glasses of water or other fluids per day, as is recommended for general health.
Learn more: Does Drinking Water Help Dry Skin? Yes
2. Use a humidifier
Low humidity can worsen winter dry skin.
Studies in humans show a reduction in transepidermal water loss (TEWL) (a measure of the integrity of the skin's barrier function) with low humidity, alterations in the water content in the stratum corneum, decreased skin elasticity and increased roughness (Goad et al, 2016).
Indeed, when your skin is exposed to a dry environment, it could be more susceptible to mechanical stress (Engebretsen et al, 2016).
Dry air can be problematic for dry skin but using a humidifier can help improve dry skin by adding moisture back into the air.
Humidifiers are devices that release water vapor or steam to increase moisture levels in the air - i.e., increase humidity.
It's best to keep indoor humidity levels between 30-50%.
If the air in your home is too dry, then your dry skin will benefit from a humidifier.
It is generally thought that humidity levels within occupied spaces should not exceed 60%, and when levels of humidity fall to around 30% or below, occupants begin to feel thermal discomfort (Goad et al, 2016).
Learn more: Does A Humidifier Help with Dry Skin? Yes!
3. Use a moisturizer with humectants
You can protect your skin's moisture barrier by using a moisturizer that contains humectants.
Humectants help to attract and hold onto water and maintain hydration in the skin.
Humectants include natural moisturizing factors (NMFs), hyaluronic acid and glycerol.
Hyaluronic Acid
Hyaluronic acid is well known as one of the major components of the dermis, and is highly hygroscopic, meaning it can absorb moisture from the air.
Hyaluronic acid provides hydration and structural integrity to the dermis (Verdier-Sévrain et al, 2007).
Glycerol
Glycerol is also known as glycerin.
Interestingly, it has been shown that glycerol is made by our skin in the pilosebaceous unit and transported through aquaporin-3 (AQP3) channels to the skin.
Endogenous glycerol plays a role in skin hydration, cutaneous elasticity and epidermal barrier repair (Fluhr et al, 2008).
The beneficial effects of glycerol on the skin have been recognized for over 75 years, and glycerol has been widely used as an ingredient of skincare formulations for its moisturizing and smoothing effects (Fluhr et al, 2008).
4. Limit exposure to cold weather
Anyone who has felt the sting of frostbite knows that cold temperatures can damage your skin.
As the skin temperature gets lower, your skin first perceives thermal discomfort, then cold and cold pain. At the same time, your skin loses finer elements of tactile sensation, it feels numb and at the end of this development your skin does not sense even pain any more (Eero et al 2002).
Frostbite can occur during cold-weather activities when the temperature is below 0°C (<32°F). When skin temperature is -4°C (25°F), ice crystals form in the blood, causing mechanical damage, inflammation, thrombosis, and cellular death. Lower temperatures, higher wind speeds, and moisture exacerbate the process (Knapik et al, 2020).
5. Protect your skin from the elements
Daily insults from the environment, such as low humidity, wind, and sun, can lower the skin's water content, causing improper desquamation and the appearance of dry, flaky skin (Verdier-Sévrain et al, 2007).
Strong wind causes winter dry skin
Strong cold winds can strip moisture from exposed skin and disrupt the skin barrier.
In a study with healthy woman, a decrease in skin hydration and an increase in dryness score were found after the exposure to cold and dry wind (Roure et al, 2012).
To protect your skin from wind damage, wear protective clothing, including a toque, face covering and gloves to protect your hands.
Sun exposure causes winter dry skin
Ultraviolet (UV) exposure from sunlight can damage dry skin.
UV energy includes UVA, UVB and UVB radiation. Each component of UV can exert a variety of effects on cells, tissues and molecules (D'Orazio et al, 2013).
Chronic exposure to UV irradiation leads to dry skin, photoaging, immunosuppression, and ultimately skin cancer (Matsumura et al, 2004).
In temperate latitudes, UV peaks on the summer solstice and is lowest at the winter solstice (Sliney et al, 2006), though indirect, diffuse UV can still be high in winter (Kerr et al, 2005).
The UV Index is low during the winter in Canada, but skiing and other outdoor winter activities can increase your exposure. Bright white surfaces like snow can double your exposure to UV. If you are skiing or doing other activities in the mountains, you will receive even more UV due to the elevation.
UV exposure from the sun is still a concern during the winter months in Canada and proper sunscreen or sunblock should be worn when spending time outdoors.
How to protect your lipid barrier
The lipid barrier is composed of epidermal lipids and sebum.
Epidermal lipids are released from keratinocytes (skin cells), and are a mixture of ceramides, free fatty acids and cholesterol. These lipids are released from skin cells and fill the spaces between the cells, like mortar or cement (Pappas, 2009).
There are several ingredients that can protect your lipid barrier:
- Emollients
- Carrier oils
- Linoleic acid
1. Emollients can protect your lipid barrier
The word emollient derives from the present participle of the Latin verb emollire, which means "to soften or soothe." Emollire, in turn, derives ultimately from mollis, meaning "soft."
Skincare ingredients that function as emollients include plant butters, vegetable and fruit oils, animal fats, and esters.
Learn more: What are Emollients? Best Emollients for Dry Skin.
What are the benefits of emollients?
The function of emollients in skincare is to soften the skin, help the skin retain its moisture and to support the skin’s barrier function.
Skin that does not have sufficient lipid content on its surface can appear dull, dry and rough. Emollients "fill in the gaps" in the skin barrier and soften it along with giving it a healthier look
The role of emollients in the treatment of dry skin conditions is often underestimated. Emollients promote optimal skin health and prevent skin breakdown, and their use can improve quality of life (Moncrieff et al, 2013; Newton et al, 2021).
Emollients are skin conditioning – the give skin a soft and smooth appearance, restoring suppleness and improving elasticity (Brown et al, 2005).
Emollients:
- Make your skin feel soft and smooth.
- Help reduce flaking and roughness from dry skin.
- Help assist the skin barrier by filling in gaps between cells.
2. Carrier oils can protect your lipid barrier
There are many sources of beneficial lipids for skin, including virgin coconut oil, hemp seed oil and apple seed oil.
Virgin coconut oil is rich in beneficial fats for the lipid barrier
Virgin Coconut oil is easily absorbed into your skin and has clinically been shown to soften and lubricate dry skin and improve symptoms of eczema (Agero et al, 2004; Verallo-Rowell et al, 2008; Evangelista et al, 2014).
Virgin coconut oil contains fatty acids including lauric acid (49%), myristic acid (18%), palmitic acid (8%), caprylic acid (8%), capric acid (7%), oleic acid (6%), linoleic acid (2%), and stearic acid (2%).
These beneficial fatty acids help nourish your skin to reduce the appearance of fine lines and wrinkles for plumper looking skin.
Read more: 5 Benefits of Virgin Coconut Oil for Your Dry Skin
Hemp seed oil is rich in beneficial fats for the lipid barrier
Cold-pressed, unrefined hemp seed oil is packed with essential nutrients, including fatty acids, vitamins and antioxidants.
Hemp seed oil is rich in n-6 linoleic acid (56%), n-9 oleic acid (11%) which soften your skin and strengthen your skin barrier
Hemp seed oil contains 16% linolenic acid, an essential omega 3 fatty acid that calms redness and irritation. Hemp seed oil also contains 5% γ-linolenic acid, a unique n-6 fatty acid with potent anti-inflammatory activity.
Learn more: 5 Benefits of Hemp Seed Oil for Dry Skin
Apple seed oil is rich in beneficial fats for the lipid barrier
Apple seed oil is rich in beneficial fatty acids, including n-6 linoleic acid (60%), n-9 oleic acid (30%) and palmitic acid (7%), which can soften and smooth your skin, and strengthen your skin barrier.
Apple seed oil is rich in various forms of vitamin E and polyphenols and has strong antioxidant activity and can protect your skin against free radical damage.
Learn more: 4 Benefits of Apple Seed Oil for Dry Skin
3. Linoleic acid can protect your lipid barrier
Linoleic acid is an essential fatty acid found naturally in healthy skin.
Linoleic acid is an essential nutrient, and your body must get linoleic acid through diet or supplements. Linoleic acid is essential for growth, reproduction, and skin function (Huang et al, 2018).
Linoleic acid belongs to the family of omega 6 polyunsaturated fatty acids (PUFAs).
Carrier oils rich in linoleic acid can soften, smooth and lubricate the skin.
Linoleic acid can be applied topically to your skin and has numerous benefits.
- Linoleic acid is an emollient and softens your skin
- Linoleic acid strengthens the skin barrier
- Linoleic acid improves dry skin symptoms
Learn more: What is Linoleic Acid? Omega 6 Essential Fatty Acid for Dry Skin
How to protect your acid mantle
Many factors can affect the pH of the skin, including age, sebum, sweat, detergents, cosmetics, and irritation (Ali et al, 2013; Yosipovitch et al, 1996).
Even rinsing your skin with water alone produces an immediate but transient increase in its pH (Gfatter et al, 1997).
Avoid high pH soap
The high pH of soap can disrupt the skin barrier
Soaps typically have a high pH of 9-10, and soap can disrupt the skin barrier.
The pH of the skin is generally in the range 4.5 to 6.5.
The high pH of soap causes swelling of the stratum corneum, which allows unwanted deeper penetration of the soap into the skin possibly causing irritation and itching (Prottey et al, 1975).
Soap can also binds to stratum corneum proteins further inducing swelling and hyper hydration of the skin. Following the completion of washing, the excess water evaporates leading to skin tightness and dryness because the soap binding reduces the ability of the skin proteins to hold water. This explains the reduction in skin hydration and elasticity following soap cleansing (Draelos et al, 2018).
To protect your skin's acid mantle, ditch the alkaline soaps!
Try using a gentle cleanser such as an oil cleanser or an oil to milk cleanser.
Learn More: 8 Types of Face Cleansers - Which Are Best for Cleansing Your Dry Skin?
Summary
Winter weather is harsh on your skin.
'Winter dry skin' is dry skin that develops during the cold winter season.
Winter dry skin appears dry, rough, and may scale and flake. It may also show premature signs of aging, like fine line, surface wrinkles and loss of elasticity.
Winter dry skin is lacking water, humectants and fats. Humectants absorb and hold water, while fats coat the skin and seal in moisture. When there is not enough water, humectants or fats, skin barrier disruption can occur, further worsening symptoms of dry skin.
To prevent winter dry skin, you must protect your skin barrier, including your moisture barrier, lipid barrier and acid mantle.
To protect your moisture barrier:
- Drink adequate water and fluids
- Use a humidifier
- Use a moisturizer with humectants
- Limit exposure to cold weather
- Protect your skin from the elements- wind and sun
- Wear a face cover and gloves to protect against wind exposure
- Wear sunscreen and sunblock to protect against sun exposure
To protect your lipid barrier:
- Use emollients for dry skin
- Use carrier oils for dry skin
- Use linoleic acid for dry skin
To protect your acid mantle:
- Avoid using high pH soaps
- Choose a gentle cleanser
- Try an oil cleanser or oil to milk cleanser
Winter dry skin is common in Canada and cold climates.
It is important to protect your skin against winter conditions to prevent winter dry skin.
Do you want healthy skin?
Sign up for Dry Skin Love Newsletter below
References
Agero AL, Verallo-Rowell VM. A randomized double-blind controlled trial comparing extra virgin coconut oil with mineral oil as a moisturizer for mild to moderate xerosis. Dermatitis. 2004 Sep;15(3):109-16.
Ali SM, Yosipovitch G. Skin pH: from basic science to basic skin care. Acta Derm Venereol 2013; 93: 261–267.
Brown A, Butcher M. A guide to emollient therapy. Nurs Stand. 2005 Feb 23-Mar 1;19(24):68, 70, 72 passim.
D'Orazio J, Jarrett S, Amaro-Ortiz A, Scott T. UV radiation and the skin. Int J Mol Sci. 2013 Jun 7;14(6):12222-48.
Draelos ZD. The science behind skin care: cleansers. J Cosmet Dermatol. 2018 Feb;17(1):8-14.
Engebretsen KA, Johansen JD, Kezic S, Linneberg A, Thyssen JP. The effect of environmental humidity and temperature on skin barrier function and dermatitis. J Eur Acad Dermatol Venereol. 2016 Feb;30(2):223-49.
(2002) The skin in the cold, International Journal of Circumpolar Health, 61:3, 277-286.
Evangelista MT, Abad-Casintahan F, Lopez-Villafuerte L. The effect of topical virgin coconut oil on SCORAD index, transepidermal water loss, and skin capacitance in mild to moderate pediatric atopic dermatitis: a randomized, double-blind, clinical trial. Int J Dermatol. 2014 Jan;53(1):100-8.
Fluhr JW, Darlenski R, Surber C. Glycerol and the skin: holistic approach to its origin and functions. Br J Dermatol. 2008.
Gfatter R, Hackl P, Braun F. Effects of soap and detergents on skin surface pH, stratum corneum hydration and fat content in infants. Dermatology 1997; 195: 258–262.
Goad N, Gawkrodger DJ. Ambient humidity and the skin: the impact of air humidity in healthy and diseased states. J Eur Acad Dermatol Venereol. 2016 Aug;30(8):1285-94.
Ishikawa J, Yoshida H, Ito S, Naoe A, Fujimura T, Kitahara T, Takema Y, Zerweck C, Grove GL. Dry skin in the winter is related to the ceramide profile in the stratum corneum and can be improved by treatment with a Eucalyptus extract. J Cosmet Dermatol. 2013 Mar;12(1):3-11.
Kerr JB. Understanding the factors that affect surface ultraviolet radiation. Optimal Engineering. 2005;44.
Knapik JJ, Reynolds KL, Castellani JW. Frostbite: Pathophysiology, Epidemiology, Diagnosis, Treatment, and Prevention. J Spec Oper Med. 2020 Winter;20(4):123-135.
Mac-Mary S, Creidi P, Marsaut D, et al. Assessment of effects of an additional dietary natural mineral water uptake on skin hydration in healthy subjects by dynamic barrier function measurements and clinic scoring. Skin Res Technol. 2006;12:199-205.
Matsumura Y, Ananthaswamy HN. Toxic effects of ultraviolet radiation on the skin. Toxicol Appl Pharmacol. 2004 Mar 15;195(3):298-308.
Moncrieff G, Cork M, Lawton S, Kokiet S, Daly C, Clark C. Use of emollients in dry-skin conditions: consensus statement. Clin Exp Dermatol. 2013 Apr;38(3):231-8; quiz 238.
Newton H. Using emollients to promote safe and effective skin care for patients. Nurs Stand. 2021 Oct 6;36(10):77-82.
Palma L, Marques LT, Bujan J, et al. Dietary water affects human skin hydration and biomechanics. Clin Cosmet Investig Dermatol. 2015a;8:413-421.
Palma ML, Tavares L, Fluhr JW, et al. Positive impact of dietary water on in vivo epidermal water physiology. Skin Res Technol. 2015b;21:413-418.
Palma L, Marques LT, Bujan J, et al. Relationship between the dietary intake of water and skin hydration. Biomed Biopharm Res, 2012; 2: 173-181.
Pappas A. Epidermal surface lipids. Dermatoendocrinol. 2009 Mar;1(2):72-6.
Prottey C, Ferguson T. Factors which determine the skin irritation potential of soaps and detergents. J Soc Cosmetic Sci. 1975;26:29- 46.
Roure R, Lanctin M, Nollent V et al. Methods to assess the protective efficacy of emollients against climatic and chemical aggressors. Dermatol Res Pract 2012; 2012: 864734.
Verallo-Rowell VM, Dillague KM, Syah-Tjundawan BS. Novel antibacterial and emollient effects of coconut and virgin olive oils in adult atopic dermatitis. Dermatitis. 2008 Nov-Dec;19(6):308-15.
Verdier-Sévrain S, Bonté F. Skin hydration: a review on its molecular mechanisms. J Cosmet Dermatol. 2007 Jun;6(2):75-82.
Yosipovitch G, Maibach HI. Skin surface pH: a protective acid mantle. Cosmet Toiletries 1996; 111: 101–112.
