Contact allergy


At a Contact allergy (allergic contact dermatitis, allergic contact dermatitis) the skin of those affected is allergic to certain substances that come into contact with it. It is reddened at the affected areas, itches, itches and it can form bubbles. Certain ointments can reduce the discomfort. Read all about the symptoms and treatment of contact allergy.

ICD codes for this disease: ICD codes are internationally valid medical diagnosis codes. They are found e.g. in medical reports or on incapacity certificates. L23ArtikelübersichtKontaktallergie

  • description
  • symptoms
  • Causes and risk factors
  • Examinations and diagnosis
  • treatment
  • Disease course and prognosis

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.

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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).

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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.

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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, the 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.