© by aha! Swiss Allergy Center - Info on allergies - Eczema/skin reactions - Contact dermatitis - belly button piercing

Contact dermatitis is one of the most common forms of skin disease. Around 15 to 20 per cent of the Swiss population have contact eczema in their life-time.

Causes and triggers

Contact dermatitis (also known as contact eczema) is an inflammatory intolerance of the skin to certain substances which is characterised by eczema. Numerous triggers are known. These are found, for instance, in jewellery, cosmetics, shampoos, hair dyes, disinfectants, cleaning products and various building materials. There are two different mechanisms that may result in contact dermatitis:

Allergic contact dermatitis

Allergic eczema occurs following contact with an allergen. Eczema may present within a few days of initial contact with the allergen. However, skin changes may also first occur weeks or even months after constant or repeated contact. In most cases, the allergen is a chemical, e.g.:

  • preservatives such as formaldehyde in cosmetics and hair shampoos
  • fragrances such as citronellol in personal care products and cleaning agents 
  • colourants such as p-phenylendiamine in dark hair dyes
  • metals such as nickel in costume jewellery.

Allergic contact dermatitis usually heals completely when all contact with the allergen is avoided.

Non-allergic or irritative contact dermatitis

Non-allergic contact dermatitis, on the other hand, is not an allergic reaction but results from exposure to a skin irritant. It is about twice as common as allergic contact dermatitis and usually takes longer to develop. The hands are most commonly affected, following exposure to physical and chemical irritants:

  • water, e.g. with repeated washing of the hands
  • UV radiation from the sun
  • moisture, e.g. saliva around the mouth
  • cleaning agents (both domestic and industrial)
  • solvents
  • cement.

Symptoms of contact dermatitis

A distinction is made between acute and chronic eczema in the allergic and non-allergic forms, based on the symptoms.

Allergic contact dermatitis

  • redness in the area of skin in contact with the allergen
  • itching (more likely allergic) or burning (more likely irritative)
  • pustules or blisters
  • weeping when pustules spontaneously burst, eventually resulting in crusts and scaling

Irritative contact dermatitis

Eczema becomes chronic if the allergen continues to have an effect or the eczema fails to heal despite the sufferer avoiding contact with the allergen. Typical signs are:

  • itching
  • redness
  • dry and/or scaling skin
  • coarsening or thickening of the skin
  • painful cracks in the skin.


Allergic contact dermatitis

It is essential to identify the cause of the contact dermatitis in consultation with the doctor. The area of skin where the irritation occurs may also indicate the allergen responsible. It may then be necessary to have skin tests (patch tests). 

Irritative contact dermatitis

The diagnosis is based on a thorough examination by a specialist. In particular, the areas of skin affected, the appearance and the sufferer’s occupation may help identify the cause.

Therapy and treatment

It is very important to avoid the causative irritant in both allergic and non-allergic contact dermatitis. Together with the doctor, sufferers closely examine and discuss objects, substances or activities that may be responsible. Once triggers are identified, alternatives should be sought. Avoiding substances that cause eczema helps cure the condition and prevent it becoming chronic.

Good skin care can restore the skin’s protective barrier. Severe eczema should be treated with topical cortisone preparations or immunomodulators after consulting a doctor.

Tips and tricks 

  • The best way to reduce the risk of occupational contact dermatitis of the hands is to wear appropriate gloves and practise good skin care. 
  • When buying cosmetics, take care to choose products that are well tolerated and do not contain potential allergens or irritants. 
  • The International Nomenclature for Cosmetic Ingredients (INCI) stipulates what information must be given about these substances. For the database, go to www.haut.de.   
  • When buying costume jewellery, ensure that it does not contain any nickel alloys. If in doubt, objects can be tested for nickel in pharmacies.

Facts and figures

Contact dermatitis is one of the most common forms of skin disease. Around 15 to 20 per cent of the Swiss population have contact dermatitis in their life-time. It may affect people in all age groups and varies in severity.

Editors: aha! Swiss Allergy Centre in co-operation with the Scientific Advisory Board. For prevalence figures, see source references.

aha! Swiss Allergy Centre helps

  • aha!shop: other booklets and factsheets provides detailed information and are available in German, French, Italian
  • aha!kinderlager for children with allergies aged between 8 and 12 years (in German or French)
  • aha!jugendcamp for youngsters aged between 13 and 16 years (in German)
  • Other education and courses on the subjects "Allergy, asthma, chronic bronchitis", "Anaphylaxis" (in German)
  • We value your opinion. Or would you like to exchange experiences with other sufferers? Find out more in german under "Advice and exchange" (in German)

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