Contact eczema

We talk of a contact eczema when contact between the skin and certain substances (e.g. occupational substances, cleaning agents, skincare products, plants) results in inflammatory changes of the skin such as redness, swelling, weeping and the formation of crusts and dry skin.

A differentiation is made between irritative (toxic) and allergic contact eczemas. An irritative contact eczema develops after a substance that is an irritant per se (e.g. acid, leach or UV radiation). An allergic contact eczema can also be caused by a normally harmless substance if a sensitisation against this substance has happened previously.

Allergic contact eczema (delayed-type allergy - type IV)

An allergic contact eczema can also develop in anyone who e.g. comes into contact with a substance that always triggers an allergy (mandatory consequence). However, a person's individual disposition also plays an important part. In addition, an impaired skin barrier can facilitate the penetration of allergens into the uppermost layer of skin (epidermis).

An allergic contact eczema is a delayed-type allergy. In other words, the changes to the skin normally do not appear until around 24 to 72 hours after contact with the allergy-triggering substance. That is why they are called delayed-type allergies. Skin contact with the allergen results in an inflammatory reaction which involves the immune cells. The clinical pattern is that of allergic contact eczema (syn. contact allergy).

Irritative (toxic) contact eczema

The most frequent cause for a contact eczema developing is existing damage to the skin. Every process that damages the skin barrier (e.g. frequent use of alkaline soap, contact with organic solvents) can result in a non-immunological, inflammatory reaction. The repeated effect of a concentration of a pollutant or irritant (noxe) that is not intrinsically irritating can induce a chronically cumulative toxic contact eczema. The effect of this is a 'wearing down' of the skin with impaired barrier function of the skin.

Special forms of contact allergy

Rare and special forms are the photo-allergenic reactions with which in addition to the allergen UV (sun) radiation must occur at the same time to trigger the reaction.

There are so-called pseudo-allergic reactions to drugs or food that are usually accompanied by highly itchy, red weals on the skin (urticaria).