Definition
A contact allergy is an allergy of the so-called late type. Here, after a previous asymptomatic contact with the substance that triggers the allergy, repeated contact causes a symptomatic reaction. There are both genetic and non-genetic factors that favour the occurrence of a contact allergy.
The most common contact allergens are nickel and cosmetics. Less frequent than the late type contact allergy is the immediate type contact allergy. Here, the very first contact with the allergen leads to a symptomatic reaction. Common allergens for such an immediate type contact allergy are plant and animal products.
Causes
A contact allergy is based on a disturbed immune reaction to a triggering allergen. With the so-called allergy of the late type, it comes after a sensitization phase, in which no symptoms occur, to a symptomatic eczema with renewed allergen contact. In the sensitization phase, the allergen meets skin cells that react by releasing various immune substances, such as Interleukin-1 and TNF-alpha.
In a complex reaction of the immune system, so-called memory cells are now formed, which remember the allergen, for example nickel. On renewed contact with nickel, these memory cells react with an inflammatory reaction, which is reflected in the typical symptoms of a contact allergy, namely swelling, redness, itching and blistering. The situation is different in the case of a contact allergy of the immediate type.
In this case, an eczema reaction already occurs after the first contact with the antigen, for example a pollen. This is caused by so-called mast cells that bind IgE antibodies on their surface. Typically, the total number of these IgE-antibodies is increased in people with such contact allergies.
You can find more about nickel allergy on our page Nickel allergyDetergens are among the typical triggers of a contact allergy. Different ingredients of the detergent can lead to the typical skin changes and the tormenting itching. A frequent cause is the softeners contained in the detergent.
Apart from softeners, fragrances are also often the cause of an allergic reaction to a detergent. A simple method to find out whether the reaction to the detergent has occurred is to change the detergent. It is preferable to use a detergent without fragrances and softeners.
Special detergents adapted to allergy sufferers are particularly recommended in this context. The specific allergy diagnosis by the dermatologist ultimately provides exact information about the cause of the contact allergy. Nickel is probably the most common contact allergen.
Today, nickel has therefore been largely banned from the production of costume jewelry, belts or metal buttons. Rarely, however, nickel is still found as a component of clothing, for example in zippers, or pieces of jewelry. A nickel allergy is usually clearly visible on the skin areas that have had contact with the metal.
These are for example the ears (wearing earrings), the belly and hips (zippers and belt buckles) or the décolleté and wrist (wearing necklaces and bracelets). Just like fragrances and other allergens, plants are among the typical triggers of contact allergies. They can cause allergies of the late type as well as aeroallergies of the immediate type.
Arnica, mugwort or chamomile are classic triggers of a contact allergy of the late type. Especially chamomile, which is very popular as a household remedy, is a frequent cause of contact allergies. Therefore, chamomile compresses around the eyes should be avoided.
Especially people who are prone to atopy (allergic tendency) develop contact allergies of the immediate type more frequently, which are caused by aeroallergens. These are especially asthmatics or people with neurodermatitis. Here, too, plant components, especially pollen, play an important role in the development of the allergy.
Tomatoes do not usually lead to the development of contact allergies. However, the consumption of tomatoes can lead to a deterioration of the skin condition in patients with neurodermatitis. The cause is not, as is often assumed, a direct allergenic effect of the tomato, but the acidity of its juice.
Onions and vinegar also have a negative effect on the skin condition of some neurodermatitis patients.Avoiding acidic foods often improves the skin. The latex allergy is usually an allergy of the immediate type. After the first contact with the allergen, reactions occur, which can go as far as anaphylactic shock.
Contact allergies can also arise from direct skin contact with objects containing latex. Persons working in the health care sector are particularly at risk, as a large amount of latex is processed there. Thus latex is found in gloves, plasters, respiratory bags or urine bags, among other things.
Objects containing latex can also be found in everyday life. Examples are household gloves, seals on doors and windows or rubber pads. In addition to medical treatment, it is recommended to avoid objects containing latex for the rest of your life in order not to provoke a dangerous, allergic reaction.
Disinfectants are often used in health care, but also in the daily life of many people. Components of the disinfectant, especially preservatives, can lead to a contact allergy. A contact allergy against disinfectants is however rather rare.
Frequent disinfecting of the hands rather leads to eczema, which has no allergic cause. The disinfectant has a strong dehydrating effect. Therefore it is very important to apply cream regularly after using disinfectant.
Woolwax can also be a possible cause for the development of a contact allergy. An allergic reaction to wool wax or wool wax alcohol is rather rare, but possible. Woolwax is contained in various cosmetic products, such as lipsticks, shaving soaps, hair shampoos or soaps.
Woolwax and woolwax alcohol can also be found in industrial greases and household products. Although sensitization in the epicutaneous test is quite common, it is only slightly specific. Therefore a use test should always be carried out. This means that after such a positive test result, one tries out on a trial basis whether an allergic reaction occurs when using products containing wool wax.
