Overview: What is contact dermatitis
Contact dermatitis occurs when the skin reacts hypersensitively to contact with certain substances. Typical signs include redness, swelling or small blisters. Itching is also common. Contact dermatitis usually only occurs on the area that has come into contact with the substance. In rare cases, a more severe reaction can also spread to other areas (so-called scattered reaction). There are many possible triggers (e.g. preservatives, fragrances, metals or cleaning agents). Experts also differentiate between allergic and non-allergic contact eczema. The latter occurs in the sense of a toxic reaction, for example to a plant or acids/alkalis.
Contact dermatitis – frequency and age
Contact eczema occurs very frequently.
In Switzerland, around 15 to 20 percent of the population are affected at some point in their lives.
Contact eczema occurs in all age groups.
However, people who frequently come into contact with possible irritants at work are particularly at risk.
These include hairdressers and cleaners, for example.
Contact dermatitis: causes and risk factors
Contact dermatitis is a hypersensitivity reaction of the body.
It occurs when certain substances act on the skin from the outside.
There are different types of contact dermatitis.
Allergic contact dermatitis
This is usually a late-type or type IV allergic reaction, which develops after repeated contact with the same substance.
This leads to a so-called immunological sensitization in the body.
As a result, the immune system reacts hypersensitively as soon as the skin is exposed to this substance (also known as an allergen) again: the typical symptoms of redness, swelling, blisters and/or itching occur.
Experts refer to this as allergic contact dermatitis, contact allergy or allergic contact dermatitis.
Special immune cells, so-called T cells, are involved in the allergic reaction.
It always occurs with a delay.
This is why allergic contact dermatitis appears at the earliest 12, but usually only 24 hours after repeated contact with the allergen on the skin.
Non-allergic contact dermatitis
In addition to allergic forms, there are also non-allergic forms of contact dermatitis.
In this case, the first contact with a toxic or irritant substance immediately causes skin reactions similar to allergic contact dermatitis.
So-called toxic contact dermatitis develops, for example, when you touch a certain plant or use certain corrosive cleaning agents.
Irritant-toxic contact dermatitis mainly develops in people who are exposed to high levels of moisture.
Due to the similar symptoms, the two forms are often indistinguishable at first glance.
This also includes sunburn (phototoxic contact dermatitis).
Possible triggers for contact dermatitis
Theoretically, any substance can trigger contact dermatitis.
However, there are a whole range of substances that are particularly well known as triggers.
For allergic contact dermatitis, for example, these are
- Metals: Especially nickel, which is found in many everyday objects such as zippers, buttons, costume jewelry, piercings, rivets and coins.
- Fragrances: These are found in most conventional cosmetics, skin care products, soaps and perfumes, but can also be incorporated into toothpaste, medicines and hygiene products.
- Dyes or preservatives (e.g. parabens, formaldehyde, methylisothizolinone), especially in cosmetics, but also in paints for wall coatings, for example
- Plants (e.g. camomile, yarrow, arnica): Certain plants can trigger contact dermatitis directly or indirectly (for example through plant extracts or essential oils contained in personal care products).
- so-called rubber additives such as vulcanizers or stabilizers for rubber production: they can be found in toys or shoes, for example.
- Epoxy resins in plastics, for example
Toxic contact dermatitis is mainly triggered by chemically or physically irritating substances such as acids, mineral oils or solvents.
However, an overdose of UV radiation can also cause the same symptoms.
Contact dermatitis: Who is particularly at risk?
In fact, there are people who are particularly frequently affected by contact eczema.
They usually work in professions where contact with certain, possibly irritating substances is part of everyday life.
Increased wet work also plays a role.
These include, for example, hairdressers, bakers, bricklayers, painters and tilers.
Cleaners or people who are mainly involved in the maintenance of machines also often develop contact eczema in the course of their working life.
Sometimes the level of suffering is so high that those affected have to change jobs because of their condition.
Symptoms: Recognizing contact eczema
The most important signs of contact dermatitis are the typical changes to the skin, such as redness or swelling.
The affected skin area may also itch, ooze or flake.
Blisters may also form.
As a rule, the skin reactions are limited to the area that has actually come into contact with the trigger (e.g. hands with cleaning products, earlobes with nickel-containing earrings).
Only in very rare cases do sufferers experience further symptoms such as scattering reactions, irritation of the mucous membranes or asthma attacks.
In the allergic form, the symptoms do not usually occur immediately after contact with the allergen, but with a time delay of 12 to sometimes 72 hours.
Here, the inflammation can sometimes spread from the original point of contact to the adjacent skin or even to completely different areas of the body.
This phenomenon is also known as a “scattering reaction”.
If contact with the irritant substance continues over a long period of time, the contact dermatitis can no longer heal properly.
We then speak of chronic contact dermatitis.
Signs of this
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Diagnosis of contact dermatitis
In order to diagnose contact dermatitis, we will ask you in detail in advance (anamnesis):
- How long have the symptoms been present?
- What is your profession?
- Where in the body do the symptoms occur?
- Is there a connection between the onset of symptoms and certain substances or activities?
- Do you suffer from other illnesses or do you already have an allergy?
Your answers will provide us with important information about your medical history.
This helps us to diagnose the contact dermatitis.
This is usually followed by a physical examination, during which we also take a closer look at the affected areas of skin.
Epicutaneous test brings clarity
To confirm the suspicion of allergic contact dermatitis, we carry out a so-called epicutaneous test (allergy test, patch test).
We test a range of substances that often trigger contact eczema or with which you are frequently in contact, for example for professional reasons.
The selected test substances are applied to the skin on your back and stuck to it with a special patch.
At regular intervals (usually after 48 and again after 72 hours) we check whether the skin reacts to any of the test substances.
Sometimes there is a third check after a further two to four days.
This is because certain allergens trigger a delayed reaction.
Important: As long as the epicutaneous test has not yet been completed, you should neither shower nor sweat heavily.
This prevents the test substance from being washed away and falsifying the result.
If typical skin changes such as redness or blistering occur during the test phase, this is proof that you are allergic to the substance in question.
If the conventional epicutaneous test does not produce convincing results, other variations of the test are available if there is a suspicion (e.g. testing directly on the eczema site or laboratory tests to examine the blood cell reaction for allergy-triggering substances).
When is the epicutaneous test not suitable?
The epicutaneous test should only be carried out if you do not have acute contact dermatitis.
As a rule, it should have been completely healed for at least two weeks.
Even if you have been in the sun a lot in the last four weeks or have had UV radiation therapy, the test must be postponed to a later date.
If you have chronic hand eczema, the test can still be carried out.
Contact dermatitis: prevention, early detection, prognosis
There are no typical signs for early detection that indicate the occurrence of contact dermatitis.
Due to the large number of possible triggers, it is also difficult to prevent in general.
However, if you already suffer from an allergy or have sensitive skin, there are various things you can do:
- First and foremost, this includes avoiding the known trigger as consistently as possible.
Certain protective measures such as gloves or special clothing can sometimes help.
- Sometimes, however, this is not enough, especially if you have a lot to do with the substance at work.
It may then be necessary for you to change your job or workplace.
In some cases, contact eczema can also be recognized as an occupational disease.
- Also make sure you take good care of your skin to strengthen its natural barrier function.
This includes not only appropriate, nourishing creams or ointments, but also special soap-free washing solutions for gentle cleansing.
For sensitive people, it is also advisable to generally avoid fragrances in cosmetics or detergents and to use cleaning agents and disinfectants as sparingly as possible.
Hand sanitizer should be rubbed in long enough, as it is designed to have a moisturizing effect after a certain rubbing time.
Course and prognosis
Hypersensitivity to certain substances usually persists for life.
Hyposensitization (i.e. specific immunotherapy) is only possible for allergies of the immediate type or type I (e.g. insect venom allergy, hay fever).
In this case, the allergic reaction occurs immediately after contact with the allergen.
Allergic contact dermatitis is a type IV allergy.
In this case, a visible reaction occurs at the earliest twelve hours after contact with the allergen.
The prognosis for contact eczema is generally good.
Normally, the appropriate therapeutic measures can quickly alleviate the symptoms.
The inflammatory reaction then subsides to such an extent that the contact eczema heals completely.
In rare cases, the symptoms can become chronic, especially if you do not avoid contact with the triggering substance.
Contact dermatitis: treatment from the outside and inside
A central component of therapy is to avoid the trigger as far as possible.
If contact dermatitis has already occurred, various treatment measures are available.
