Cosmetic Allergies And Dermatitis: What They Are And How To Avoid Them
There is still a lot of confusion when it comes to allergies or dermatitis caused by cosmetics use. This is because, despite having completely different induction mechanisms, the acute reactions are very similar such as redness, edema, erythema, papules, vesicles or bubbles. So let’s try to clarify.
The safety assessments on a cosmetic product aim to determine whether an ingredient, inserted in that product, can potentially induce irritation or sensitization under normal use conditions and also in the possible incorrect use event. Depending on the product being evaluated, it will be necessary to select the most suitable test type that takes into account the application frequency, duration, location and methods.
Irritative contact dermatitis is an inflammatory skin reaction that does not involve the immune system and has characteristics and evolution based on the irritant type that caused it, the method and use time and also the individual susceptibility. Irritative contact dermatitis in its acute form is often confused with an allergic reaction precisely because of the skin manifestations similarity. With time passage, acute irritative dermatitis can lead to its chronic form which is characterized by a barrier function alteration of the skin associated with an increase in cell turnover.
The main test for assessing the skin’s irritative power is the epicutaneous Patch Test which can be performed in different ways: occlusive with the patch application, or in open application. It can also be performed with single or repeated application to highlight any cumulative substance effects. Any irritation effects are evaluated at set times after applying the product and removing the occlusive patch.
Allergic reactions, on the other hand, are caused by a specific immunological response to a specific substance applied to the skin. In this case, it’s about skin sensitizing power when a substance, called allergen, is able to penetrate through the epidermis, bind to its carrier receptor and thus activate the immune system cells such as mainly Langerhans cells and T cells.
If contact is made between a sensitizing substance and the skin, within 24-48 hours there is an inflammatory reaction that persists up to a few days with edema, redness, itching and blisters. A sensitization reaction can expand and become chronic, transforming over time into allergic contact dermatitis with permanent aesthetic and functional damage. The sensitizing power evaluation takes place through the patch test with repeated insult.
Eyes and Face: the Parts Most Affected by Cosmetic Allergy
Particular attention should be paid to the eye allergy manifestations from cosmetics. Eye irritation tests have been developed to ascertain the potential of a given substance to produce redness, burning, itching but also conjunctivitis, iris swelling or cornea opacity after a single application. Eye irritation adverse events normally return to normal levels after 21 days. Before carrying out in vivo experimental tests, it’s possible to obtain useful information by analyzing the available data published by studies on animals or humans, knowing the chemical-physical substance properties, in particular the pH, or searching for other data on previously performed studies in vivo relative to the mucous membranes.
Generally speaking, cosmetics should not be applied in the area near the eye. The specific application on the eye contour is supported by the monitored ophthalmological tests and by doctors and ophthalmologists who monitor the product application for about a month on volunteers.
Cosmetic Dermatitis: The Symptoms And What To Do
The irritative contact dermatitis symptoms, as it could occur following the cosmetic products use, can involve both the epidermis superficial layers manifesting itself with scaling or hyperkeratosis phenomena, and the deeper inflammatory layers response leads to the appearance of redness, vasodilation, papules, vesicles and edema.
Symptoms of a cosmetic allergic sensitization reaction are predominantly erythema, edema, papules, vesicles or blisters up to systemic level involvement. To make a correct diagnosis, it’s advisable to rely on the patient’s history analysis and an accurate dermatological examination.
In mild skin irritation symptoms event, it may be sufficient to suspend the cosmetic use. In the most serious and severe cases, especially of allergic reactions, it may be necessary to use antihistamines and / or cortisones. In case of doubts or uncertainties, the doctor or pharmacist advice is always recommended.
If consumer is aware of allergies to certain substances or irritation events that occurred previously following the product use, it’s advisable to apply a small amount in an out of sight skin point, preferably in the forearm, and wait 24 to 48 hours to ensure that not adverse reactions occur.
What are hypoallergenic cosmetics and what is the repeated insult patch test
More than hypoallergenic products, it’s more correct to speak of cosmetics formulated to reduce the allergy risk.
The cosmetic ingredients that have been found to be most responsible for allergic reactions are dyes, perfumed essences and preservatives.
The hypoallergenic cosmetic claim is one of the most attentive claims by the control bodies. If used only in reference to the fragrance that has been included in the product, it indicates that the fragrance does not contain any of the 26 substances with the greatest allergenic potential or that it contains small quantities such as not to be able to trigger an adverse reaction in some allergic or intolerant.
These allergens can be found on the cosmetics label with the following names:
- Alpha-isomethyl ionone
- Amyl cinnamal
- Amylcinnamyl alcohol
- Anise alcohol
- Benzyl alcohol
- Benzyl benzoate
- Benzyl cinnamate
- Benzyl salicylate
- Butylphenyl methylpropional
- Cinnamal
- Cinnamyl alcohol
- Citral
- Citronellol
- Coumarin
- Eugenol
- Evernia furfuracea
- Evernia prunastri
- Farnesol
- Geraniol
- Hexyl cinnamal
- Hydroxyisohexyl 3-cyclohexene carboxaldehyde
- Hydroxycitronellal
- Isoeugenol
- Limonene
- Linaool
- Methyl 2-octynoate.
In the generic case of a hypoallergenic product, it’s necessary to make sure that all the necessary tests and evaluations have been carried out as it may contain various substances capable of giving an allergic reaction. To have a cosmetic that is as hypoallergenic as possible, the presence of known allergens and even allergen precursors must be avoided, taking into consideration substances classified as irritants or sensitizers at various levels by scientific committees (such as, for example, some preservatives or dyes used in hair dyes) and also data on adverse events recorded by post-market cosmetovigilance.
The patch test for cosmetics with repeated insult is the test used to evaluate the sensitizing product power and consists in exposing the skin to the potentially sensitizing product in a repeated and controlled manner, for example 48-hour applications repeated for 3 weeks. After at least 2 weeks suspension period, another single-dose occlusion application is performed and parameters such as erythema, edema, desquamation are evaluated after 72 hours of removing the product. This type of test is performed for products addressed to a particularly susceptible consumers target such as children, subjects with sensitive skin, products for the ocular or labial mucosa.
Hypoallergenic cosmetics: advice for allergy sufferers
Considering, as mentioned before, that we cannot properly speak of hypoallergenic cosmetics, it’s difficult to define a cosmetic suitable for allergic people as the substances that cause irritation or allergies can be different.
Surely among the substances most subject to this type of problem are perfume allergens. It is advisable to read carefully on the label the presence of one or more of the 26 substances defined as allergens.
Even the presence of Nickel could cause allergy problems, so make sure that the product has been tested for this heavy metal.