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 contact allergies. 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.
The table of contents for this article shows the various subtopics related to contact allergies. Simply click the heading with your mouse to jump to the section you want.
What happens in a contact allergy?
A contact allergy can develop when the immune system becomes sensitized to a specific 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 detach from the button upon contact with the skin.
In the event of an allergy, the immune system responds by forming T lymphocytes. These are helper cells that attack the perceived threat, causing inflammation in the process. Special T memory cells ensure that an invader recognized once is fought again and 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 12 hours later or even after three days.
These are type IV allergies of the so-called delayed type. That is why it can be difficult to trace 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 occur at the site of contact.
In severe cases, itchy crusts and scales form, similar to psoriasis. The longer the contact with the allergen, the more severe the allergic reactions can be. With continued contact, there is a real risk that a chronic contact eczema will form, with thickened, 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 known as a spreading reaction of the contact allergy.
Other health risks of chronic contact eczema
Every injury to the skin's surface provides an entry point for germs. Itching blisters or hives should therefore never be scratched. This is particularly critical in cases of chronic contact eczema, which causes cracks and grooves in the skin where fungi or bacteria can settle.
A feeling of heat at the affected area, swelling, severe redness, and pain signal the resulting infection . Further treatment with antibiotics or antifungal medications may therefore be necessary. It is especially important for people with weakened immune systems to identify contact allergies so that they can avoid their triggers.
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, and 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 diet, or genetic predisposition increase the likelihood of 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. The so-called transition metal nickel is an important industrial metal used, for example, to manufacture stainless steel and a wide variety of alloys.
Nickel is therefore a common component of coins, jeans 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 breaks out, it manifests as nickel dermatitis, whose effects can range from scaly skin, papules and blisters, itching, redness, and pain to the development of allergic contact eczema. If the allergy is not recognized and contact with nickel is not interrupted, the affected area of skin may become chronically thickened.
Further complications may also 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 should 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 from allergen-free materials are available.
Incidentally, since 1994 the EU has had guidelines governing the permitted nickel content of objects that remain in contact with the skin for extended periods. Complaints 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 manufacture 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 production of latex gloves and other products, are also frequently responsible for the allergic reaction.
Unlike most contact allergies, latex allergy is not limited to a late reaction. In some cases, the allergy is caused by proteins in latex and manifests as an immediate 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 by “immediate-type latex allergy,” causing a runny nose, coughing, or even shortness of breath. A delayed reaction occurs when substances such as thiurams are the triggers. As a late reaction of class IV, 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 been enacted to prevent new cases of latex allergy. For example, powdered latex gloves may no longer be used. The powder containing latex particles could be absorbed not only through skin contact but also through the respiratory tract.
Nowadays, many alternative materials are also available that are not considered allergy triggers - for example, synthetic rubber. Even in the medical field or in caregiving, where protective gloves are indispensable, latex gloves can be replaced by 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 because 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.
Vinyl-nitrile gloves: These are hybrid gloves made from a combination of vinyl and nitrile. Vitrile combines the advantages of both materials without compromising on 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. Pure cotton gloves are therefore 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 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 thorough medical history - an interview in which your medical history is carefully taken.
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 beneath a plaster, this indicates an allergy to the substance tested. According to current scientific knowledge, desensitization is not possible for contact allergies. The only way to live without symptoms is to completely avoid the allergen.
For example, wear protective gloves when you have to handle metal objects if 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 various wavelengths, an active ingredient called psoralen is used, which makes the skin 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 skincare 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 emollient oil baths or cleansing lotions, to keep the skin's surface clean gently. Naturally, with all skincare products, which often contain natural ingredients such as arnica, vine leaves, or other plant extracts, care should be taken to ensure that you are not allergic to these ingredients.
If you have a contact allergy, be sure to have it examined and treated by a doctor – including with regard to possible skincare products. Avoid contact with substances 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 completely avoid the allergen.
