Contact allergies or contact allergic dermatitis – eczema, is caused by an allergic reaction to substances coming into contact with the patient’s skin. In hypersensitive persons, these contact allergens cause itching, redness, papules, and later also flaking and peeling of the skin.
When eczema is in the acute phase, the skin becomes red and swollen, extremely itchy, with small blisters which break, resulting in scabs and whitish, flaking skin deposits. If contact with the allergen is continuous or chronic, the skin thickens, becomes dark red, sometimes dark brown and flaky, and painful cracks appear. Itching is minimal, but constant, or it worsens from time to time.
The most important therapeutic objective is to find out the root cause – the allergen. In order to identify the allergen responsible for the skin changes, epicutaneous testing to standard allergens of the European series is performed. This series contains some of the most common allergens on European territory. They include various substances, ranging from metals found in jewelry, to dyes, food preservatives or scents found in hair dyes and other cosmetic products, to substances found in some glues, cement, rubber and other objects people are in daily contact with. Epicutaneous or patch tests are easily performed, but require time in order to give reliable results. Patches with allergens are applied to the back and are kept on for 48 hours, after which time they are removed and the results can be interpreted. Additional readings are also required after 72 hours, and sometimes even after 96 hours in order to ascertain whether there is an allergic reaction or an irritation caused by a chemical substance.
A particular type of contact dermatitis – eczema – develops in contact with some plants such as poison ivy, as well as plants used for medicinal purposes. Propolis, for example, is a common ingredient in many medicinal substances and it is found in many cosmetic products, yet it can be a strong allergen and cause eczema in some people. Allergic reactions can also be caused by the so called natural cosmetics with herbal components, as well as industrial cosmetics which contain perfumes and certain preservative agents. The safest solution for sensitive skin and allergy-prone skin are well tested products without added perfumes and preservative agents. If a certain cosmetic product is suspected to cause eczema (face, eyelids, hands, neck), it is best to perform epicutaneous testing not only with the standard series of allergens, but also with cosmetic products frequently used by the patient.
Allergy to jewelry
Nickel is the most common allergen causing contact dermatitis, it is found in bijoux jewelry as well as in many other metal objects: metal buckles, hand watch bracelets, coins, metal glasses. It can also be found in silver jewelry, as well as in gold jewelry, although in such small quantities that it does not cause a manifest reaction in most persons. Stainless steel also contains nickel, but it is bonded in such a way that it is difficult to dissolve during contact with cookware and other stainless steel objects. Sweating is conducive for nickel seeping from metal objects, so some people have manifestations only in warm weather and when sweating profusely. A contact rash is most common on earlobes from earrings, in contact with a metal buckle on pants or under a wrist watch.
Latex products are also common causes of allergies, primarily latex rubber and other additives used in rubber manufacturing. Latex allergies can cause skin changes, but also a skin rash, teary eyes and breathing difficulties. Manifestations of latex allergy are common in contact sites of underwear with the skin, if it contains latex; and some types of shoes can cause allergies on the feet.
Hair dyes allergy
Most people do not experience problems with hair dyes, but some people are allergic to paraphenylenediamine, which can cause redness of the scalp after hair coloring treatments. This substance can be found in dark permanent and semi-permanent hair dyes, as well as in temporary tattoo pigments, resulting in redness, swelling and itching at the site of the tattoo. Substances similar to paraphenylenediamine can also be found in clothing, so that dark clothes, especially made of polyester and nylon, can cause allergic reactions in some people.
Cosmetic products allergy
Perfumes, lotions and other cosmetic products can cause allergies – these are primarily scents and preservatives in cosmetic products. This is why fragrance-free products should be selected, because they do not contain scents. Also, medical cosmetic products which do not contain preservatives should be chosen. Testing the cosmetic products used by a person prone to allergies is the best way to determine which of them are safe to use. Natural cosmetics which contain herbal components which have not been sufficiently tested can also cause contact dermatitis.
Allergy to plants
There are numerous plants which can cause contact dermatitis. Sometimes it is manifested only on the contact site, such as the hands of a person working in a florist shop, and sometimes the airborne pollen can cause changes on the eyelids, face and hands, as well as other exposed parts of the body. Sometimes, the cause can be herbal balms containing some allergenic plants, which are commonly used in traditional medicine for wrist pain and swelling (such as comfrey). Another type of allergy is phytodermatitis, where simultaneous exposure to the plant and exposure to sunlight causes either skin redness with painful blisters or dark discoloration of the skin. The plants which cause such a reaction are lemons, limes, parsnip, celery and some sorts of flowers, as well as perfumes worn before going to the beach.
Chromium and chromium salts allergy causes eczema in persons who are in contact with cement, leather, some types of dyes, some types of matches, as well as rust protection products. They can cause eczema on the feet, whereas in persons who are in contact with cement, the cement dust can easily cause changes throughout the body in the form of a generalized eczema.
Neomycin is an antibiotic found in many creams and ointments for topical skin use, which can cause an allergic reaction. A typical reaction is the daily worsening at the injury sight which was treated for an abrasion or other injury with a topical antibiotic.
Treatment of contact dermatitis
The approach to treating eczema is first of all in identifying the cause of the eczema by giving advice and information about substances which should be avoided. In case of a mild skin rash, short term application of a corticosteroid or immunomodulating cream will be sufficient, and in the case of pronounced itching, an antihistamine is also needed. If there is a strong reaction with changes all over the body surface, systemic immunomodulating therapy (corticosteroids, photo(chemo)therapy etc.) is needed, and if there is also a secondary infection, antibiotic treatment is needed.
Spec. Dr. Svetlana Djurisic, dermatologist
Dermatological clinic DERMATIM, Belgrade