Sometimes the cosmetic products we use on our skin can trigger an adverse response, be it irritant or allergic in nature. In this guide to dermatitis and cosmetics, Alex Gazzola looks at the kinds of responses cosmetics can cause, how to get diagnosed if you have a problem, and how to avoid your triggers.

We use cosmetics to benefit our skin and make us look, feel and be healthier, but when the skin appears to react to a product, it can be an obvious concern.

Dermatitisis the general term used for any form of inflammation of the skin, with symptoms of itchiness, dryness, redness and, over time, possibly cracking and coarseness. When this is caused by something coming into direct contact with your skin, such as a cosmetic, chemical, plant, or item of clothing, it is called contact dermatitis.

Irritant vs Allergic

When you use a cosmetic or toiletry which you feel may be causing your skin to react, it’s difficult to know what the nature of the reaction is. Is it a genuine allergy or a mere irritation?

In all, there are four kinds of contact dermatitis.

Irritant contact dermatitis is the most common type, accounting for 80% of cases. It does not involve the immune system so is not an allergy.

Irritant contact dermatitis can be acute (a quick inflammatory response, within hours or even minutes of contact, with symptoms of blistering or a burning sensation) or chronic (a delayed response which builds up, sometimes taking days or months to develop, eventually resulting in thickened, scaly and dry skin).

Possible irritants include detergents and solvents which strip the skin of its protective oils and make it more vulnerable and sensitive. People working with chemicals – cleaners, hairdressers, gardeners – often develop some degree of irritant contact dermatitis. The reactions tend to become milder with ongoing use or exposure.

Allergic contact dermatitis is less common, and its reactions tend to worsen with increased exposure to the allergen. It is a delayed type IV allergic reaction, occurring between 24 and 72 hours after exposure, and it can be due to chemicals such as perfumes and preservatives which come into contact with the skin. Symptoms include blistering, rashes, swelling and reddening at the site of contact.

It is difficult to distinguish between the two. Allergic contact dermatitis is more likely to be itchy and localised to the point of contact, while irritant contact dermatitis may be more painful and widespread.

Contact urticaria is a rapid and acute skin reaction, which could be a type I (IgE-mediated) reaction. Urticaria is the classic red, itchy nettle rash, with raised bumps or wheals that look like a clustering of insect bites. It may occur in response to touching nuts, fruits or latex, for example, should you be allergic to these, and in the case of food substances, the offending allergens may be found as cosmetic ingredients. Other cosmetic ingredients may cause the reaction too.

(There is also a type of ‘false’ allergy-like reaction which mimics type I contact urticaria and may be experienced by up to 20% of the population from time to time. The symptoms are similar, but the immune system is not involved, although histamine release does occur in the skin’s layers. This can be triggered by exercise, pressure on the skin, extremes of temperature and even cold or hot water, for instance. Often, the causes and mechanism are unknown.)

Photocontact dermatitis is a form of dermatitis triggered by the action of sunlight on a substance interacting with the skin. In other words, both light and the chemical are required to trigger the reaction. It can be either non-allergic or allergic, with the former typically producing symptoms like sunburn on the skin, and the latter similar to typical allergic contact dermatitis described above. Typical problem substances include some sunscreens and fragrances, but this form is quite unusual.

All types of reactions above, both irritant and allergic, are more common in people who have other allergies (food allergy, eczema, asthma, hay fever) and problem skin conditions (such as psoriasis).

Testing and diagnosis

Irritant or allergic contact dermatitis may be indicated when symptoms ease after weekends or during holidays, when occupational exposures are avoided or changes in routine affect the substances you come into contact with.

The parts of the body affected by the dermatitis may also suggest a contact exposure is the problem – the face may imply a face cream, the hairline a hair dye, and the armpit a deodorant, for example. But allergens and irritants can easily be transferred around the body – such as an irritant in nail varnish being transferred when you scratch yourself – so the connection is not always so obvious.

If your doctor or dermatologist suspects contact dermatitis a full investigation is warranted via patch testing, in which various test substances are diluted in a base and applied to the skin, usually the back, and covered in an aluminium disc and adhesive tape to secure them.

After 48 hours, the tape and discs are removed and the skin examined. Another 48 hours later, it is examined again. During both examinations the scale of any reactions – determined by factors such as redness, swelling and blistering – is gauged and scored, and then compared.

* An irritant reaction is one which is prominently symptomatic after 48 hours, but resolves noticeably after 96 hours.

* An allergic reaction, however, is more severe after 96 hours than it is at 48 hours, as it is slower to develop.

Another test which may be used is the repeat open application test (ROAT), which is sometimes helpful in settling an uncertain patch test result, or to better establish the significance of a seemingly mild reaction. This involves applying a suspect chemical or product twice daily to a spot on the forearm for a week to see whether dermatitis results.

Allergic contact urticaria is diagnosed via traditional allergy testing techniques (eg prick testing).

Photocontact dermatitis is diagnosed in much the same way as ordinary contact dermatitis, but with duplicated patch sets, one of which is irradiated with UVA light after twenty-four hours.

The Key Allergens / Irritants

With thousands of potential irritants and allergens used in cosmetics and other chemicals to which we can be exposed, it is impossible to test for them all.

Your dermatologist will probably choose a standard contact dermatitis testing battery, such as the European Baseline Series, International Standard Series or the British Contact Dermatitis Society (BCDS) Standard Series. Standard testing batteries vary slightly, and the substances included in them are occasionally subject to revision, but generally they include 30 or so substances and mixes which account for around 85% of all contact dermatitis reactions.

This is the guideline minimum on which a dermatologist may build a tailored, more extensive set of allergens to test you. Other occupational chemicals (eg the BCDS hairdressing battery, if you work in this field) may be included, as well as any cosmetic products you use regularly. Specific fragrances and compounds may need to be ordered from laboratories or cosmetic manufacturers and prepared individually.

Some dermatologists use Diagenics’ ‘True Test’, which is a ready-made patch test system of 29 allergens.

Several cosmetic ingredients are included in the baseline standards, including formaldehyde, parabens mix, balsam of Peru, and fragrance mixes. Also included are many other extracts which can cause dermatitis via other means of contact – for instance nickel sulphate, to test for nickel allergy from jewellery.

In the case of contact urticaria, assorted substances may be tested for via skin pricking, but particularly latex, a common allergen.

Fragrances (Parfum)

Several thousand fragrances are used in the cosmetics industry and, at least theoretically, all can trigger contact dermatitis. This can make it difficult, even impossible, to identify individual problem chemical(s). A natural fragrance is just as likely to be a problem as an artificial fragrance (though of course you may wish to avoid artificial fragrance for other reasons). Oak moss and clove are among the most allergenic.

By an amendment to the EU Cosmetics Directive in 2005, it is now law that 26 fragrances deemed to be the most allergenic must be named on all cosmetic products (and household chemicals) when present in concentrations of at least 10 parts per million (leave-on products) or 100 parts per million (rinse-off products / household chemicals). These fragrance compounds must also be named when they form a part of an essential oil included in the ingredients. (16 of the 26 occur naturally in essential oils.) The list of fragrance allergens is given in Table 1.

The list is not without its critics, and many experts have called for its revision. One relatively recent study [] found that while some of the 26 are common allergens in practice, others are rarely problematic (although could be severe when they occur).

Fourteen of the 26 allergens are included in fragrance mixes I and II, found on most baseline testing series.

Balsam of Peru

This is a sticky liquid with a vanilla / cinnamon aroma, derived from the myroxolon balsamumtree. It is used in perfumes, toiletries, foods, drinks and many medicinal products. It’s a common allergen, and is tested individually on all standard patch series.


Preservatives are necessary to prevent bacterial spoiling and lengthen shelf life. There are around fifty approved for use in cosmetics. Several are found on the standard patch test series, so will automatically be tested for. A number can trigger contact dermatitis, including:

* Formaldehyde – a preservative used in cosmetics and deodorants;

* Quartemium 15 – a formaldehyde-releasing agent used in many cosmetics;

* Parabens – a group of preservatives usually excluded from natural/organic skincare products (due to unrelated safety fears), but common in other products;

* Many others, including imidazolidinyl urea, diazolidinyl urea, BHT and EDTA.

PPD (PPDA / p-phenylenediamine / paraphenylenediamine)

This common allergen is a colourant often used hair dyes, temporary tattoos and brown / black henna (ie adulterated henna) products. Reactions to it can occasionally be severe.

Lanolin (wool alcohols)

Lanolin is a mix of natural substances, such as wool alcohols and fatty acids, obtained from the fleece of sheep. It is a common allergen, and terms such as ‘wool fat’ and ‘lanolin alcohol’ may indicate its presence. It is an excellent emulsifier, therefore found in many cosmetics, toiletries, medicinal creams and emollients. Up to 5% of cosmetic allergies may be due to lanolin.


If you have food allergies, you may want or need to avoid the same allergens in leave-on cosmetics. Many botanicals are used in cosmetics, but often only the Latin names are provided on ingredients lists. A list of food allergens in Latin is given in Table 2.

If you have coeliac disease, you may like to avoid gluten-grain ingredients, which can be found in creams, shampoos and other products. According to Coeliac UK, there is no risk to coeliacs in using skincare products with wheat in them, but anecdotally many have reported reactions, and others choose to avoid them regardless. The Latin for wheat is ‘triticum vulgare’.

Occupational irritants

Hundreds of potential irritant chemicals exist, and some examples are provided in this link at the Health and Safety Executive’s website: []


Having identified allergens or irritants, your dermatologist will advise you on avoidance and give you helpful leaflets. These will tell you:

a/ the names and alternative names / synonyms of your allergens to help you identify them on labelling;

b/ in which products the allergens or irritants may be found (this may include cosmetics, medicines, household products, cleaning chemicals, clothing, furniture, foods and food ingredients, and much more);

c/ other ingredients, chemicals, foods and products to which you may also react (via cross-reactions);

d/ possible safe alternative products (if they exist).

What this boils down to is you will have to read cosmetic labels carefully (and possibly other labels such as food labels). All cosmetic products sold in the European Union (EU) must display a complete ingredients list on the product or its packaging. Cosmetics which are small and difficult to label are partially exempt; instead, their ingredients should be displayed close to the point of sale or available on a leaflet.

Ingredients must comply with European law and use the International Nomenclature of Cosmetic Ingredients (INCI) – a standardised form of naming products, used throughout Europe, and also in other countries.


The presence of fragrances in products is denoted by the word ‘parfum’ in ingredients lists.

If you have been diagnosed with an allergy to one or more fragrance you may be advised to avoid all fragrances, unless you know the particular fragrance(s) to which you react and can find products which are free from them. In the case of the 26 key fragrance allergens, this can be gleaned from the label, but if you are allergic to others you may need to contact the manufacturer to check whether they are included. Some manufacturers are reluctant to disclose details of formulations, however, so you may have either to resort to trial and error – which can be expensive and frustrating, and can risk sensitising you to other fragrances – or else just avoid all. This may be the better option as cross-reactions are always a possibility too.

No perfume’ / ‘Unscented’ / ‘Fragrance free’

Astonishingly, these terms do not necessarily mean that there are no fragrances in the product. The terms can be merely descriptive, and refer to the lack of any perceptible aroma. None guarantees that, for instance, a masking fragrance has not been used to disguise the smell of other ingredients. The BCDS has highlighted the case of Simple Skincare products, which use the term ‘No perfume’ on its products, some of which contain fragrance chemicals, such as citronellol, limonene and linalool. Always read the ingredients label instead, and look out for ‘parfum’ and other ingredients such as essential oils named.


This terms does not mean ‘allergen-free’ but ‘low allergen’. It denotes that ingredients less likely to trigger contact dermatitis reactions have been used in the product. Although not a legal requirement, it is highly likely that the 26 key fragrance allergens will be excluded from hypoallergenic preparations.

Preservatives and other allergens

Increasing numbers of natural and organic skincare manufacturers exclude certain chemicals from their preparations, including allergenic preservatives and emulsifiers.


Avoidance is obviously key, and will help resolve most cases in time.

Emollients / moisturisers may be all you additionally need to soothe remaining irritation, although you must choose one free of your allergens (many contain lanolin, for instance).

Steroid creams may be advised, as these help reduce inflammation. Mild ones can be bought over the counter, but stronger ones must be prescribed. Again, these creams can contain allergenic ingredients, such as hydrocortisone.

Barrier creams can help reduce contact with an occupational chemical, but their use is controversial, and they can encourage you to take less care with avoidance.

Other products, such as anti-histamines, oral steroids and oral antibiotics, may be advised for particular cases.

Useful Links

The European Cosmetics Assocation:

The Cosmetic Toiletry & Perfumery Association:

The British Contact Dermatitis Society:

The European Society of Contact Dermatitis:


Table 1

The 26 fragrance allergens which must be listed on cosmetic ingredients according to the Seventh Amendment to the EU Cosmetics Directive:

Alternative name in brackets.

Description / INCI Name­                Testing Battery­

Alpha-Isomethyl Ionone­                     ­-­

Amyl Cinnamal­       ­                            FM I­

Amylcinnamyl Alcohol­                    ­     -­

Anisyl Alcohol­         ­                            -­

Benzyl Alcohol­         ­                           -­

Benzyl Benzoate ­     ­                           -­

Benzyl Cinnamate­  ­                             -­

Benzyl Salicylate­     ­                            -­

Butylphenyl Methylpropional­

(Lillial­)                                                 -­

Cinnamal­                   ­                          FM I­

Cinnamyl alcohol­    ­                             FM I­

Citral­                           ­                        FM II­

Citronellol­                  ­                          FM II­

Coumarin­                   ­                          FM II­

Eugenol­                       ­                        FM I­

Evernia Furfuracea­ (Treemoss)­           -­

Evernia Prunastri­   (Oak Moss­)            FM I­

Farnesol­                      ­                        FM II­

Geraniol­                      ­                        FM I­

Hexyl cinnamal­        ­                            FM II­

Hydroxy-citronellal­                               ­FM I­

Hydroxyisohexyl 3-Cyclohexene
Carboxaldehyde­ (Lyral)­                       FM II­

Isoeugenol­                  ­                         FM I­

Limonene­                   ­                          -­

Linalool­                       ­                         -­

Methyl 2-Octynoate­                             ­-­

FM I and II – Fragrance Mixes I and II are included on both the European Standard Series and The British Contact Dermatitis Series.

This article was first published in Allergy Newsletter No. 102, Summer 2011.