Contact dermatitis

Contact dermatitis (also known as contact eczema) is a non-infectious reaction of the skin to external substances and influences and is one of the most common diseases of the skin.

Causes and triggers

Contact dermatitis is a collective term for non-infectious skin diseases in which the skin reacts to certain substances with eczema. More than a thousand possible triggers are known. These are contained, for instance, in jewellery (nickel), cosmetics, shampoos, hair colorants, disinfectants, cleaning products, various building materials and impregnating agents. People who have sensitive skin in any case, e.g. people with neurodermatitis (atopic dermatitis), have a stronger tendency to react to these substances. There are two different mechanisms by which contact dermatitis can arise:

Allergic contact dermatitis

This involves intolerance of a substance where the immune system reacts by producing specific immune cells. Inflammation develops as a consequence. Nickel, lanolin, Peru balsam or potassium dichromate are common triggers of contact dermatitis of allergic origin. These substances can be found in jewellery, medication applied topically, cosmetics or in cement and impregnating agents, among others. 

Irritative contact dermatitis

Irritative contact dermatitis is not an allergic reaction, but excessive strain on the skin due to physical and chemical irritants. The skin is stressed because of repeated irritation from substances such as water, soap, disinfectants, etc. In addition, physical influences such as rubbing, pressure, heat and cold or UV rays can cause irritation. People whose jobs include working in moist conditions, such as hairdressers, nurses, cooks, cleaning staff and industrial workers, are commonly affected. This form is far more common than allergic contact dermatitis. 

Symptoms of contact dermatitis

Allergic contact dermatitis

The reaction usually occurs 24–48 hours after contact with the allergenic substance. The skin is inflamed and reddened, it may swell up and blisters or papules may appear. These symptoms are often combined with severe itching. The skin reaction appears at the site of the body where the skin came into contact with the irritant, but may also spread to nearby or remote regions of the skin. On repeated contact, it may eventually lead to painful cracks (rhagades), scaling or thickening of the skin.  

Irritative contact dermatitis

It mainly appears on the hands or occasionally the feet as well. The severity of the irritation is dependent on the nature and intensity of the causative substance, the region of the body and the sensitivity of the skin. Irritative eczema usually develops more slowly than allergic eczema. Irritative contact dermatitis commonly appears as redness of the skin, sometimes swelling as well. Blisters or cracks may appear, often accompanied by a feeling of tightness and burning. The skin changes are always confined to the contact area. 

Neither allergic nor irritative contact eczema is contagious. 

Diagnosis

Allergic contact dermatitis

The cause of the contact dermatitis needs to be discovered in discussion with the doctor. The area of skin where the irritation occurs may give an additional indication of what triggered the irritation. The next step may involve taking skin tests (patch tests). 

Irritative contact dermatitis

The diagnosis is based on a thorough examination by a specialist. The causes may be concluded particularly from the affected parts of the skin, the appearance and the sufferer’s occupation. 

Therapy and treatment

Avoidance of the causative irritant plays a very important role in allergic as well as irritative contact dermatitis. Together with the doctor, sufferers look closely at and discuss objects, substances or activities that may be responsible. Once triggers are identified, alternatives should be sought. Avoiding substances that cause eczema makes it possible to cure the condition and prevent a prolonged course. 

Antihistamine tablets can provide some relief of itching, but antihistamine gels have a rather irritant effect. Severe eczema should be treated with topical cortisone preparations after consulting a doctor.

Tips and tricks 

  • The development of severe contact dermatitis can be avoided by early diagnosis and compliance with appropriate measures. The use of skin-neutral washing and care products can prevent additional irritation.  
  • Wearing gloves when working with irritating or allergenic substances and regular application of skin protection creams are the best countermeasures to prevent the development of contact dermatitis on the hands. 
  • It is important to watch out for nickel-free alloys when buying fashion jewellery. If in doubt, objects can be tested for nickel in pharmacies. 

Facts and figures

Contact dermatitis is one of the most common diseases of the skin. Around 20 per cent of the Swiss population is affected by contact dermatitis of varying severity during the course of their lives.


Editors: aha! Swiss Allergy Centre in co-operation with the Scientific Advisory Board.

 

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