Origination

The genetic predisposition to react to the various dermatitis triggers plays an important role.

If someone has a genetic (inherited) disposition to show dermatitis, this is called “atopy”. Dermatitis that develops in this situation is called "eczema" or “atopic eczema.

Many people have this disposition unknowingly. Besides the increased probability for eczema, it also increases the probability to develop so-called atopic diseases, e. g. hay fever. The inflammations can also change location and move from the skin to the respiratory tract (asthma) or other mucous membranes (running nose, irritated and streaming eyes).

Among these body functions are for example the menstrual cycle in girls and women, the hormonal metabolism in general, developments like ageing, which is related to the loss of elasticity of the skin, and individual events like infections and stress. All these factors trigger the discharge of substances within the body, their transport to the skin by the blood circulation and the skin’s reaction to this.

These inner factors can be especially important for the course of eczema. More...

The main triggers in eczema are of endogenous (internal) character. Among them, the mind is the most important factor, that means our mental wellbeing. Mind and eczema can influence each other in a “vicious cycle”.

Effects of the mind on eczema

Every kind of mental stress can have an impairing influence on the skin. Mourning a break-up, homesickness, exam nerves, a job interview, conflicts with friends – all this can suddenly cause itching. This reaction can be explained as follows: our nervous system influences the immune system, which causes an intensified inflammatory reaction.

Effects of eczema on the mind

Just as our mind has an impact on eczema, eczema also has an impact on our mind. During an acute episode, the skin discharges inflammatory substances (“mediators”) that travel through the blood system into the central nervous system (brain, spinal cord). During an episode people suffering from eczema may therefore be particularly sensitive, irritable and restless.

The inner restlessness that may accompany strong itching may lead to lack of sleep. This increases irritability and the capability to deal with stress goes down: small events can lead to tensions and aggravate the condition. The lack of sleep can lead to reduced concentration at school and work and reduce performance, which causes additional potential for conflict.

Changes in visible parts of the body, especially in the face, can have negative consequences: the reaction of the people around you (curiosity, astonishment, sympathy etc.) can lead to social withdrawal. Looking into the mirror can become a nuisance. Patients can be seen as principally introverted, withdrawn or little outgoing, while this behaviour has nothing to do with their general personality but is simply caused by their health condition. Eczema can literally “work on your nerves".

Irritant contact dermatitis (subtoxic cumulative dermatitis)

Irritant contact dermatitis is neither triggered by an allergy nor does genetic disposition play an important role.

The term “wearing dermatitis” explains a bit better what the cause of this skin condition is. Contact dermatitis develops when the skin is irritated by an aggressive substance. With a certain dosage and exposure time, any person would develop contact dermatitis. “Subtoxic” means that the substance is not strongly irritating for the skin (= “toxic”) but only “slightly irritating”. “Cumulative” expresses that the frequent (=cumulative) contact with a substance causes the skin condition.

The most frequent trigger substances for subtoxic cumulative contact dermatitis are water, soap, shampoo, cleaning substances, acids, bases and solvents. A mechanic skin irritation like rubbing can aggravate a skin lesion additionally. Affected by this type of dermatitis are especially persons that have to deal regularly with skin irritating substances, e. g. in the household, in the medical field by regular hand washing, and hairdressers.

As it is often not easy to classify dermatitis according to its appearance, it may become necessary to do some allergy testing. In addition, the skin irritability can be tested by bringing a slightly irritating substance onto the skin and observing the reactions.

Therapy includes the reduction or avoidance of contact with the irritating substances, careful skin care and, if necessary, the use of protective gloves in certain activities.

Allergies

Allergies form a very specific form of influence on the skin condition. The number of allergies has strongly increased in the past decades.

Allergies are skin reactions to natural substances (polls, cat hair, latex) or artificial substances (hair dyes, soap). As soon as the immune system has become contact with the substance classified as alien, e. g. when inserting an earring into the earlobe, a chain reaction is unleashed: as defence against the intruder, the skin area swells and reddens.

Specific allergies are not inherited, but what you may inherit is the increased risk to acquire allergies in the course of your life. But the way your body reacts (which chain reaction it produces) is genetically determined. Allergies are a reaction that the body “learns” in the course of life. They can also change the location of reaction.

There is also one form of dermatitis which is basically caused by an allergic reaction: so-called allergic contact dermatitis .

Medical scientists differentiate between an immediate reaction type and a late reaction type. The names indicate that, in the case of an immediate reaction type, the reactions occur immediately after contact with the allergen (e. g. hay fever), while in the late reaction type they occur some time after the contact (hours to days).

Allergic immediate response (type I allergy)

The allergic immediate response (type I allergy) is the prototype of an allergic reaction.

It appears seconds to minutes after contact with the allergen. The triggers are mostly natural substances. Typical examples for this allergy type are hay fever (running nose), allergic asthma (dyspnoea, coughing) and the anaphylactic shock following insect bites (anaphylactic reactions).

The most frequent trigger substances in the immediate allergic reaction type are grass and birch pollen, house dust mites, mould and cat's hair.

Type I reactions can be determined by a prick test, laboratory tests and a thorough evaluation of the patient history. In a prick test, the suspected trigger substance is placed onto the skin and the skin is slightly pricked. The response is controlled after 20 minutes.

Allergic late response type (type IV allergy)

The allergic late response type (type IV allergy) is the cause of contact allergies of the skin.

This type is a reaction to substances that get in contact with the skin directly (e. g. nickel in jewelry; cosmetics), by the air (perfume, fragrances, solvents), or by oral intake through the blood system (medication). In type IV allergies, the reactions appear only after hours to days.

Type IV reactions are determined by a so-called “patch test”. The suspected trigger substances are placed in very low concentrations on the back of the patient under a plaster. After 2 to 3 days the doctor controls if dermatitis has developed.

Allergic contact dermatitis

The allergic contact dermatitis is usually the result of a type IV allergy (allergy of the late reaction type).

The immuno-competent cells must have had contact with the triggering substance at least once. When an allergy develops (this is called “sensitization”), specific immuno-competent cells “save” the “data” of this substance and define it as dangerous for the body.

As soon as the body, after this sensitization, gets exposed to this substance again, the substance is identified on the base of the “saved data” and the defence reaction is initiated.

The consequence is allergic contact dermatitis with reddening, blisters and itch. Such an allergy usually develops in the course of years. In exceptional cases, a sensitization can also emerge within 7 to 10 days. Important to know: the “data storage” will never be emptied again in life; an allergy will persist for the rest of your life.

These are the most frequent trigger substances for allergic contact dermatitis: metals (especially nickel, very often contained in costume jewellery, metal buttons, belt-buckles, belt-eyes etc., then cobalt and potassium-dichromate), additives used in rubber production, cosmetics (fragrances, additives), medicines, disinfectants, e. g. formaldehyde, epoxy resin (e. g. used in the plastics and electrical industry).

With the start of a vocational career, occupation related substances start to play an important role. In children and adolescents, an increasing number of allergies to henna tattoos can be found nowadays. The trigger substance is not the henna itself but p-Phenylenediamine (PPD), a chemical colouring substance that is often added to the henna to increase colour intensity and stability.