Contact allergy

Contact allergy: description

Contact allergy is an overreaction by the immune system to a specific substance that has come into contact with the skin. The affected skin areas are allergic, they inflame and itch.

The contact allergy is relatively common. More than one quarter of the population in Germany is allergic to at least one substance after skin contact.

In an allergy, the body’s defense system is directed against substances that are actually safe. These substances are called allergens in this case. They consist of vegetable or animal proteins, but also of inorganic substances such as metals, and are usually harmless. If the immune system still fights them, it is called an allergic reaction.

The contact allergy is a so-called late-type allergy. It is characterized by the symptoms occurring only 24 hours to three days after contact with the allergen. Responsible for the reaction are certain cells of the defense system. Upon contact with the allergen, these so-called T cells emit messenger substances that lead to an inflammatory reaction. The inflammatory reaction is then the visible skin change.

Nickel is the most common contact allergen. But other metals, plants or fragrances can trigger a contact allergy.

Contact allergy: symptoms

A contact allergy manifests itself in changes in the skin that occur about one to three days after skin contact with the allergen. In those areas where the skin has been in contact with the allergenic substance, the following symptoms may appear:

• Skin redness (erythema)
• Swelling (angioedema)
• weeping bubbles
• wheal
• Crusting or dandruff
• Itching or burning

If skin contact persists, chronic contact dermatitis develops. The skin becomes coarser, keratinized and forms grooves (lichenification).

Contact allergy: causes and risk factors

Any substance that occurs in the environment can theoretically cause a contact allergy. However, the most common allergens are:

• Metals (eg nickel in jewelery, zippers, buttons)
• Fragrances (eg in perfumes, soaps, cosmetics)
• preservatives
• Plants (eg chamomile, mugwort, arnica)
• essential oils (eg lemon or peppermint oil)
• Cleaning agents (eg plasticizers)
• Latex (eg as latex gloves)

Some factors may increase the risk of developing allergy. A genetic bias, environmental pollutants, high-fat foods, smoking and alcohol, but also excessive hygiene can promote the development of allergy.

Contact allergy: examinations and diagnosis

In order to make the diagnosis of contact allergy, the doctor initially interviews the patient in detail about his medical history (anamnesis):

• When did the symptoms first appear?
• Are the symptoms limited to a skin area?
• Is there something that will ease the discomfort, for example, if you avoid certain garments or jewelry?
• Are allergies already known?

After the doctor has examined the corresponding skin more closely, he will perform a patch test. In this case, a sample of the candidate allergenic substances is applied to the back of the patient and covered with patches. After one or two days you remove the patches. The doctor then assesses the local response to the various substances. If skin rash has developed or wheals have formed, this indicates an allergic reaction to this substance.

Toxic contact dermatitis

In contrast to allergic contact dermatitis, skin changes in toxic contact dermatitis are not caused by an allergic reaction, but by toxic substances such as acids or alkalis. For example, cleansers can trigger toxic contact dermatitis on the hands. The skin changes are very similar to an allergic reaction.

Contact allergy: treatment

A contact allergy can not be completely cured. Sensitization to the substance usually lasts a lifetime. Nevertheless, it is possible to alleviate the symptoms. It is particularly important to avoid contact with the allergenic substances. The affected skin should also be well cleaned to aid the healing process. Moisturizing and care products help the skin to rebuild. We recommend moisturizing creams, oils or baths.

drugs

If necessary, a cortisone-containing ointment may be applied to the skin. Cortisone inhibits the excess immune response and thus reduces the inflammatory response in the skin. The type of cortisone and the duration of use must be carefully weighed by the doctor against the known side effects of the treatment: Cortisone can make prolonged use, among other things, the skin thinner and blotchy. Therefore, cortisone-containing preparations should be applied only briefly and on small areas of skin.

If the topical application of the ointments does not result in the desired healing of the skin, cortisone-containing tablets may also be taken in some cases. Again, it is important that they are used only briefly and under medical supervision, as significant side effects may occur.

In case of chronic hand eczema, the doctor may prescribe the active ingredient alitretinoin for ingestion. It has anti-inflammatory and regulating the immune system. Because of its teratogenicity, women of childbearing potential must provide effective contraception during treatment and four weeks thereafter.

UV therapy

For chronic eczema (especially chronic hand eczema), UV therapy can help. Either irradiations with UV-B light (UVB therapy) or irradiations with UV-A light in combination with the active substance psoralen (PUVA therapy) are used. Psoralen is taken for example or applied locally on the skin.

Contact allergy: disease course and prognosis

A contact allergy usually lasts a lifetime. Depending on which allergens the affected persons react to, how strongly the immune system was sensitized and how long the contact with the allergenic substance lasts, the symptoms can be more severe or milder. When the triggering agents are avoided, the symptoms often disappear by themselves within two to three weeks.

If a contact allergy persists for a long time, the affected skin can be infected by fungi or bacteria. The skin then becomes warm, is severely reddened or swollen and hurts. An infection is treated with antibiotics or antimycotics depending on the pathogen.

Prevent the contact allergy

A contact allergy usually occurs without harbingers, there is no prophylaxis. However, one can try to reduce the risk of allergies in general. It is known, for example, that breastfed babies are less likely to suffer from allergies. When children grow up in households with animals, this also reduces their risk of developing allergies.

If you already suffer from a contact allergy, the allergenic substance should be avoided. Special clothing and gloves protect the skin. Sometimes certain activities, for example, at work, have to be completely avoided. In the case of a professional contact allergy, you should contact the company doctor or the professional association. In these cases a professional dermatological consultation is possible. Partially the Contact allergy also recognized as an occupational disease.