Contact allergies are triggered by various substances or materials that come into direct contact with the skin. You have surely heard of a nickel allergy or a latex allergy before – nickel and latex are among the best-known triggers of a contact allergy. However, they are far from being the only substances that cause problems for those affected. The symptoms of a contact allergy include severe itching, a rash, or even the formation of so-called contact eczema. The tricky thing is that days can pass between contact with the allergen and the allergic reaction, making this allergy particularly difficult to identify.
In the table of contents for this article, you can see the various subtopics relating to contact allergies. Simply click the heading with your mouse to jump to the desired section.
What happens with a contact allergy?
A contact allergy can develop when the immune system becomes sensitized to a particular substance, even though it is completely harmless. In the case of a nickel allergy, for example, sensitization occurs through direct contact between a nickel-containing trouser button and the skin. A few microscopic nickel particles are released from the button when it comes into contact with the skin.
In the case of an allergy, the immune system responds by producing T lymphocytes. These are helper cells that attack the perceived threat and cause inflammation in the process. Special memory T cells ensure that an intruder recognized once is always fought again – and more quickly – in the future.
Contact allergies never appear upon first contact with the allergen. And when they are triggered during a later contact, the first symptoms often do not appear until after 12 hours or even after three days.
These are type IV allergies of the so-called delayed type. Therefore, it can be difficult to identify a contact allergy. The reason for the delayed immune response is the long journey of T helper cells from the lower to the upper layers of the skin.
Typical symptoms of a contact allergy are redness and swelling of the skin in the affected area, accompanied by itching or a burning sensation. Hives or oozing blisters may also appear at the site of contact.
In severe cases, itchy crusts and scales form, similar to psoriasis. The longer the contact with the allergen persists, the more severe the allergic reactions may be. With continued contact, there is a real risk that chronic contact eczema will develop, with hardened, cracked skin.
Occasionally, delayed symptoms may occur on other parts of the body, even if they have not come into contact with the substance in question. This is a disseminated reaction to the contact allergy.
Further health risks of chronic contact eczema
Every injury to the skin's surface provides an entry point for germs. Itchy blisters or hives should therefore never be scratched. The situation becomes particularly critical with chronic contact eczema, which causes cracks and fissures in the skin where fungi or bacteria can settle.
A feeling of heat at the affected site, swelling, severe redness, and pain signal the resulting infection. Further treatment with antibiotics or antifungal medication may therefore be necessary. It is especially important for people with weakened immune systems to identify contact allergies so that their triggers can be avoided.
What are known triggers of contact allergies?
Various substances are known to trigger contact allergies. These include metals such as nickel, latex from natural rubber, fragrances, preservatives, or plasticizers in cleaning products. Plant-based products such as essential oils, as well as various plants themselves, can also cause sensitization upon skin contact.
It is suspected that factors such as exposure to pollutants, smoking, poor nutrition, or genetic predisposition increase the likelihood of developing a contact allergy. The most common contact allergies probably involve nickel and latex.
Nickel allergy – allergic to a metal
Nickel allergy is the most common contact allergy. Nickel, the so-called transition metal, is an important industrial metal used, for example, to manufacture stainless steel and various alloys.
Nickel is therefore a common component of coins, trouser buttons, belt buckles, and costume jewelry. The metal is found in many objects that come into contact with human skin in everyday life. According to various European studies, contact with the allergen nickel can lead to sensitization in up to 10–25 percent of the population.
However, this does not mean that these people will also develop symptoms. Approximately 8–10 percent of adults in Germany suffer from an active nickel allergy. Women are affected up to four times as often as men.
When a nickel allergy develops, it manifests as nickel dermatitis, the effects of which can range from scaly skin, papule and blister formation, itching, redness, and pain to the development of allergic contact eczema. If the allergy is not recognized and contact with nickel is not stopped, the affected area of skin may become chronically thickened.
In addition, further complications may result from inflammation of scratched-open blisters and eczema. Nickel can also be absorbed through food in smaller amounts - potatoes, for example, also contain some nickel. In rare cases, this can intensify existing symptoms.
In the event of an allergy, contact with nickel must be avoided at all costs. Make sure that objects containing nickel do not come into direct contact with bare skin. Protective gloves can be worn to protect the hands. Jewelry containing nickel must be avoided - alternatives made of allergen-free materials are available.
Since 1994, the EU has also had regulations specifying the permitted nickel content of objects that remain in contact with the skin for extended periods. Symptoms caused by inhaling nickel particles are recognized as occupational diseases. This can occur in industrial environments, for example during nickel processing. In everyday life, the nickel concentration in the air we breathe is very low.
Latex allergy - in two forms
Natural latex is made from the sap of the rubber tree. The material is used, for example, to make medical protective gloves, condoms, and carnival masks. Rubber trees are also popular houseplants, but some people develop a latex allergy to the plant sap and everything made from it.
So-called thiurams or dithiocarbamates, which are only formed during the industrial manufacture of latex gloves and other products, are also often responsible for the allergic reaction.
Unlike most contact allergies, latex allergy cannot occur only as a late-type reaction. In some cases, the allergy is caused by proteins in latex and manifests as an immediate-type reaction within minutes of skin contact. Urticaria is a typical symptom and appears as itchy welts on the affected areas of skin.
The respiratory tract can also be affected in cases of “immediate-type latex allergy” by a runny nose, coughing, or even shortness of breath. A delayed reaction occurs when substances such as thiurams are the triggers. As a late-type class IV reaction, latex allergy manifests after several hours or days through the development of contact eczema. In rare cases, latex allergy can cause anaphylactic shock.
Since the 1990s, various laws have come into force that are intended to prevent new cases of latex allergy. For example, powdered latex gloves may no longer be used. The powder mixed with latex particles could be absorbed not only through skin contact but also through the respiratory tract.
Many alternative materials are now also available that are not considered allergy triggers - for example, synthetic rubber. Even in the medical field or in care work, where protective gloves are indispensable, latex gloves can be replaced with gloves made of nitrile, vitril, vinyl, or cotton.
Make sure to buy gloves labeled thiuram-free and/or dithiocarbamate-free, as these substances can sometimes also be found in materials other than latex.
Nitrile gloves: Nitrile gloves are a good alternative to latex gloves, as they also provide excellent tactile sensitivity, are flexible and tear-resistant, and are resistant to numerous chemicals, fats, and oils. Nitrile gloves are used in the medical field, in laboratories, and by care and cleaning services. They are also suitable for handling food.
Vinyl gloves: Vinyl is a soft, comfortable material with an extremely smooth surface. Vinyl gloves are also available in powdered form, among others - the powder makes them easier to put on and take off and is intended to reduce sweating of the hands.
Vitrile gloves: These are hybrid gloves made from a combination of vinyl and nitrile. Vitrile combines the advantages of both materials without compromising quality.
Cotton gloves: Cotton is a material that does not cause contact allergies. Of course, allergies to chemicals and other substances in cotton products can still occur. This is why pure cotton gloves are used in the medical field. Due to their soft and comfortable texture, they are suitable, for example, as examination gloves or as a gentle liner under other gloves. Cotton gloves can generally be washed or sterilized in an autoclave using hot steam and reused.
The latex-fruit syndrome is a cross-allergy that occurs in more than one-third of people with a latex allergy. Those affected experience allergic reactions after eating fruit. However, some vegetables such as tomatoes or peppers, as well as nuts, potatoes, or buckwheat, can also trigger cross-allergies with latex.
How is a contact allergy diagnosed and treated?
In some cases, it is easy to determine that a contact allergy is causing symptoms such as a rash, blisters, or eczema. Although the symptoms develop gradually, it is clear to see that, for example, the wrist where costume jewelry was worn is affected.
It is more difficult if you do not know at all what material you came into contact with in the 12–72 hours before the first symptoms appeared. The effects of contact allergies are easily confused with atopic dermatitis, psoriasis, and other skin irritations. Every medical examination therefore begins with a detailed medical history – a discussion in which your medical history is recorded in detail.
Your doctor will examine the affected areas of skin and initiate further treatment.
To diagnose a contact allergy, a special skin test is performed: the so-called patch test. Patches containing small amounts of the respective allergens are applied to the back, where they remain for up to two days.
If a rash develops under a plaster, this indicates an allergy to the substance tested. According to the current state of scientific knowledge, hyposensitization is not possible for contact allergies. The only way to live free of symptoms is to completely avoid the allergen.
For example, wear protective gloves if you have to handle metal objects when you have a nickel allergy.
Acute symptoms can be treated with cortisone-containing ointments. Cortisone can dampen the immune system's overreaction, but should not be used for an extended period. If a cortisone ointment is not sufficient, cortisone tablets can be taken for a short time – but only under medical supervision.
Cortisone can cause serious side effects and may have a negative impact on the muscles, metabolism, or bone structure, among other things.
UV therapy can be used to treat contact eczema. In addition to UV irradiation at different wavelengths, a substance called psoralen is used, which allows the skin to absorb even more UV light.
If polymorphous light eruption (sun allergy) is also present in addition to the contact allergy, UV therapy is naturally not an option.
Careful skin care cannot prevent a contact allergy, but it does help the skin recover from rashes and eczema. Moisturizing and nourishing creams and balms can be applied after the symptoms have healed to support the skin's natural regeneration.
In some cases, using an antiseptic cream may be advisable. Also advisable are refatting oil baths or cleansing lotions, to keep the skin's surface gently clean. Naturally, with all care products, which often contain natural ingredients such as arnica, vine leaves, or other plant extracts, care should be taken to ensure that there are no allergies to these ingredients.
If you have a contact allergy, be sure to have it examined and treated by a doctor – also with regard to possible care products. Avoid contact with substances that you believe may harm you until an allergy test can provide clarity.
Once a contact allergy has been identified, precautions can usually be taken to avoid the allergen completely.
