SKIN IRRITATION OR ALLERGY?

The use of facial skin care cosmetics can lead to adverse skin reactions, which most often take the form of contact irritation or contact allergy. Although the symptoms of both reactions may be similar, their immunological mechanisms, causes, and clinical consequences differ significantly. Understanding the differences between these conditions is crucial for both consumers and dermatology and cosmetology professionals.

Skin irritation and allergy after using cosmetics - differences, mechanisms and epidemiological data

Contact Skin Irritation

skin irritation mechanism

Irritant contact dermatitis (ICD) is the most common skin reaction caused by cosmetics. Its mechanism is not immunological, but results from direct damage to the epidermal barrier by chemicals contained in the product. The most common irritant ingredients include alcohols, preservatives, fragrances, and acids and bases used in cosmetics.

Applying several cosmetics to the skin at the same time or in a short period of time can also lead to irritation, especially if their ingredients interact. The mechanism of this phenomenon may result from several factors, such as the accumulation of irritants, a change in skin pH, destabilization of the cosmetic formulation or chemical reactions between ingredients.

Some cosmetic ingredients have the potential to irritate on their own, but their combination can intensify the effect. For example, alcohols (e.g. ethanol, alcohol denat.) used in toners or anti-acne products can increase the skin's permeability to other substances and intensify irritation. AHA/BHA acids (e.g. glycolic, lactic, salicylic acid) used simultaneously in different products can cause excessive exfoliation and weaken the skin's protective barrier.

Some ingredients require a specific pH to be effective, and mixing them can lead to adverse reactions. Vitamin C works best at a low pH (<3.5), while niacinamide prefers higher values ​​(~5-7). Combining them can lead to an increase in pH and loss of effectiveness of both substances, as well as temporary skin irritation.

Using retinoids after AHA/BHA acids increases the risk of irritation if used concurrently with retinoids, which are strongly irritating on their own.

Some ingredients can react with each other to create substances with potentially irritating effects. An example of this is the reaction between benzoyl peroxide and retinoids. Benzoyl peroxide can oxidize retinol, which leads to its inactivation and at the same time increases the risk of irritation.

Mineral oils, i.e. petroleum derivatives, create an occlusion, which may increase the penetration of active substances and their potentially irritating effect.

Some ingredients, especially in occlusive creams, can cause substances applied earlier to penetrate deeper into the skin than normal, which can lead to irritation or an allergic reaction. Silicones and paraffin in moisturizers can trap irritants on the skin, prolonging their effects. Emollients and acids used together can cause occlusion to increase the exfoliating effects of acids, leading to dryness and irritation.

How to avoid irritation resulting from ingredient interactions?

Skin irritation caused by interactions of cosmetic ingredients can be minimized by conscious care planning and appropriate use of products. The order of application of cosmetics, avoiding an excessive number of active substances in one routine, gradual introduction of new preparations, as well as protection of the skin from external factors, such as UV radiation, are of key importance.

The correct order of applying cosmetics affects their effectiveness and minimizes the risk of irritation. Products should be applied according to their consistency and effect on the skin. Generally, cosmetics with a lower pH are used first, which penetrate deeper layers of the skin more easily and can actively affect its structure. Examples are AHA and BHA acids and vitamin C in the form of ascorbic acid, which work best in an acidic environment (pH 3-4).

After applying low pH cosmetics, you should wait a few minutes for the ingredients to absorb and work effectively. Then you can move on to moisturizing products that restore skin balance and help rebuild the hydrolipid barrier. Finally, protective cosmetics are used, such as sunscreens, which prevent the degradation of active ingredients and protect the skin from the negative effects of external factors.

Combining several powerful active ingredients in one skincare routine can lead to excessive skin burden and irritation. An example of an unfavorable combination is the simultaneous use of retinol and AHA/BHA acids. Retinol, a derivative of vitamin A, has a regenerative effect and stimulates cell renewal, but it can also cause redness and peeling of the skin. AHA and BHA acids, which exfoliate dead skin cells, additionally increase the risk of irritation if used at the same time as retinol.

A similar risk is posed by combining vitamin C in the form of ascorbic acid with niacinamide – these ingredients have different pH requirements, which can lead to their destabilization and reduced effectiveness. To avoid irritation, it is best to use these ingredients at different times of the day, e.g. vitamin C in the morning and retinol or acids in the evening.

New cosmetics should be introduced into your skincare routine gradually to assess how well your skin tolerates them. You should test each new product for at least a few days, preferably by first applying it to a small area of ​​skin (e.g. behind the ear or on the inside of your wrist). If there are no adverse reactions after 24-48 hours, such as redness, burning or itching, you can gradually add the product to your daily skincare routine.

Special care should be taken with cosmetics containing strong active ingredients, such as retinoids, exfoliating acids or benzoyl peroxide. It is best to introduce them at intervals of a few days, so that the skin has time to adapt. Otherwise, it may cause irritation, dryness of the skin or weaken its natural protective barrier.

Sun protection is a key part of your skincare routine, especially when using ingredients that can make your skin more sensitive to UV radiation. Retinoids, AHA/BHA acids, and vitamin C can make your skin more susceptible to sun damage, leading to the risk of discoloration, photoaging, and irritation.

Let us remember that conscious skin care, including the correct order of applying cosmetics, avoiding unfavourable combinations of active ingredients, gradual introduction of new products and regular use of sun protection, helps minimise the risk of irritation and increases the effectiveness of cosmetics.

symptoms of skin irritation

Symptoms of ICD include redness, burning, tightness, and in more severe cases, swelling, peeling, and vesicles. Unlike an allergy, the reaction occurs immediately or within hours of contact with the irritant and is usually limited to the site of application. Chronic irritation can lead to thickening of the epidermis and increased dryness of the skin (Johansen et al., 2022).

Contact allergy - mechanism and symptoms

Contact allergy ( ACD ) is a type IV (delayed) hypersensitivity reaction that is T-cell dependent. It occurs after previous sensitization to a given substance – initial contact with the allergen leads to its presentation by Langerhans cells and activation of the immune system. Subsequent exposure to the allergen results in an inflammatory reaction in the skin, the symptoms of which usually appear after 24–72 hours of contact (Peiser et al., 2012).

The most common allergens in cosmetics are fragrances (e.g. linalool, geraniol), preservatives (e.g. methylisothiazolinone, parabens) and dyes and excipients (Heisterberg et al., 2011). Symptoms of skin allergy include erythema, swelling, itching, and in more severe cases – blisters and exudates. Unlike contact irritation, the reaction can also occur outside the place of application of the cosmetic.

Epidemiology and Statistics of Adverse Skin Reactions

According to epidemiological studies, contact irritation accounts for the vast majority of adverse reactions to cosmetics. It is estimated that ICD accounts for about 80% of contact dermatitis cases , while ACD accounts for about 20% (Diepgen et al., 2016).

Data from the European Network on Contact Allergy (ESSCA) indicate that allergy to cosmetic ingredients affects 1 to 4% of the population , depending on the region and study methodology (Uter et al., 2020). People with atopic predisposition and people who frequently use products containing highly allergenic substances, such as hairdressers, beauticians and chemical industry workers, are particularly at risk.

In studies conducted in the United States, preservatives and fragrances were the most common cause of allergic reactions – formaldehyde allergy was detected in 8–9% of patients tested for cosmetic allergens, while methylisothiazolinone was responsible for approximately 6% of cases (Warshaw et al., 2017).

What else can cause redness and burning of the skin after using a cosmetic? One of the reasons may be providing too large a dose of active ingredients to which our skin is not accustomed, because so far we have only used ordinary drugstore creams, the effects of which are much weaker than the effects of natural cosmetics full of natural plant extracts. Such skin is not accustomed to such a strong dose of active ingredients and may react with redness and irritation. Sometimes the solution is to mix the cream with the active ingredient with another simple cosmetic, e.g. hyaluronic acid or shea butter.

Both irritation and contact allergy after cosmetics are significant dermatological problems. Irritation is a direct reaction resulting from damage to the epidermal barrier, while allergy is an immunological mechanism that requires prior sensitization. Due to the high incidence of skin reactions to cosmetics, it is crucial to consciously choose products with a mild composition and to use patch tests to identify allergenic substances.

Bibliography:

• Diepgen, T. L., Ofenloch, R. F., Bruze, M., et al. (2016). Prevalence of contact allergy in the general population in different European regions. British Journal of Dermatology , 174(2), 319-329.
• Heisterberg, M. V., Menné, T., Johansen, J. D. (2011). Contact allergy to preservatives in cosmetics: I. Frequency of sensitization . Contact Dermatitis , 64(6), 325-329.
• Johansen, J.D., Aalto-Korte, K., Agner, T., et al. (2022). Irritant contact dermatitis. British Journal of Dermatology , 187(1), 19-32.
• Lazarov, A., Trattner, A., Abraham, D., et al. (2019). Contact dermatitis due to personal care products. Clinics in Dermatology , 37(3), 298-305.
• Peiser, M., Tralau, T., Heidler, J., et al. (2012). Allergic contact dermatitis: epidemiology, molecular mechanisms, in vitro methods and regulatory aspects. Cellular and Molecular Life Sciences , 69(5), 763-781.
• Uter, W., Geier, J., Frosch, P.J., et al. (2020). Contact allergy and allergic contact dermatitis. Current Dermatology Reports , 9, 1-13.
• Warshaw, E. M., Raju, S. I., DeKoven, J. G., et al. (2017). Prevalence of contact allergy in North America: Results from the North American Contact Dermatitis Group (NACDG) . Dermatitis , 28(5), 298-306.

HOW TO DIFFERENTIATE IRRITATION FROM ALLERGY?

Natural cosmetics contain a very high concentration of active ingredients (significantly higher than in drugstore products) to have an intensive, strong effect. Unfortunately, there is no rule and some people may react more strongly to such a change and feel greater discomfort, while for some the skin will definitely switch to a solid dose of good ingredients more quickly. Also, when the skin is in worse condition, it can also react with stronger irritation.

Both irritation and allergic reactions are individual issues. Each skin is different, reacts differently and can also react with irritation when we combine different cosmetics with different natural ingredients. Not every natural ingredient will like and react correctly with another natural ingredient from another cosmetic. With capricious, sensitive skin, you have to test a lot to find the right product for yourself.

IRRITATION HAS OCCURRED - WHAT SHOULD I DO NOW?

Should you absolutely stop using the cream or use it anyway? The most important thing is to carefully observe your skin when using it for the first time. If after applying the cream you feel a slight burning sensation, tingling or redness appears on the skin, which disappears within 40 minutes, it does not necessarily mean an allergy. Some active ingredients have a very strong effect and cause intentional, temporary hyperemia of the skin, which indicates that the active substances have started to work. We should stop using the cream when the redness does not disappear, we feel a prolonged burning sensation and additionally a rash appears.

It is also worth adding, which few of us know, that in most cases we are dealing with ordinary contact irritation. What does that mean? Redness and burning appear only in the application sites. When we are dealing with an allergy, the skin reaction can be much more extensive and also appear in other places than the application sites.

Let's also remember to use the products according to their intended use! For example, a face cream contains a higher concentration of active ingredients than a cream from the same series dedicated to the eyes, because the skin under the eyes is much thinner and more delicate than the skin of the face and needs different, more delicate care. Using a face cream under the eyes can cause burning, redness, and even other more serious irritation!

LET'S GIVE NATURAL COSMETICS A CHANCE!

If we already know that we are not dealing with an allergy, it is worth giving the cream a chance and using it for a while. This slight redness at the beginning of use shows that the cream is working. The problem is that the skin was not ready and accustomed to such a large dose of active ingredients - before using the cosmetic, it could have been excessively dry, irritated or damaged.

Therefore, let's give natural cosmetics a chance to develop their capabilities and slowly switch it to the action of strong active ingredients, and consequently improve its condition and support its natural metabolism.

ALLERGIC TO ANY INGREDIENTS

In addition, we must remember that natural cosmetics are made from natural ingredients, such as honey, propolis, rose oil, which can cause allergies in people who are allergic to these ingredients. It is worth knowing that not only chemical substances can cause allergies, but also natural ones! Even those that have a soothing and calming effect will not show such properties in people who are allergic to this substance, and can irritate our skin.

So find out what your body is allergic to!

Don't rule out natural products!