Contact Allergy

We talk about contact allergy when there is a reaction of the body in case of contact with an allergen on the skin. For several years, the frequency of contact allergies has been increasing. Allergy to latex, cosmetics, perfumes, nickel (denim buttons, jewelery) with henna (tattoos that are done on vacation on the beach) … The three main manifestations of contact allergy are atopic eczema, urticaria and conjunctivitis.


The confusion between urticaria and eczema is common.

Urticaria  is formed of red, blistered plaques with well-defined contours of variable size and number. These plaques are always associated with often intense itching. It is said that they are “netted” plates in reference to nettle stings. An urticaria plaque is also fleeting, staying only a few hours at the same place. Urticaria is often accompanied by edema in the extremities (face, hands, feet). These oedemas are normal skin color, itch little and disappear more slowly in 24-48 hours, always without a trace.

Conversely,  eczema , whether it is atopic eczema or allergic eczema of contact, is manifested by red plaques, with poorly defined contours, covered with small crusts or dry skin. The itching is again important.

From the allergological point of view, there is no skin lesion whose appearance makes it say that it is an allergy. Indeed, the majority of edemas and urticaria are not allergic. And this also applies to eczema.



Atopic eczema is a disease that affects the skin and mucous membranes. The most common symptoms of this disease are:

  • Irritation lesions occurring on very dry skin
  • Redness
  • Itches
  • Peeling (skin peels) and crusts sometimes

In young people, eczema is located mainly inside the wrists, knees or elbows but also on the face and upper body.

The allergens involved

  • Animals
  • mites
  • Ivy, geranium or pelargonium
  • Some beauty products
  • Etc.

But allergens are not always directly involved, baths or showers too long, cold air in winter, stress, sometimes some viral infections can worsen atopic eczema.

2 %

Atopic eczema reaches 2 to 10% of adults [1]



Contact eczema causes localized eczema plaques at the point of contact with a product to which one is allergic. Test patches identify the responsible product which must then be definitely avoided.

The allergens involved

  • Perfume
  • Nail polish
  • Ephemeral tattoos with (fake) henna
  • Preservatives of cosmetics
  • Etc.



Urticaria is an itchy rash that appears on the skin. The main symptoms of urticaria are:

  • Lesions (which look like nettle bites)
  • Red plates
  • Severe itching

When urticaria is localized in the head, hands or feet, it can progress to a swelling that can become very impressive especially in the face (with risk of edema inside the mouth or mouth). throat). In case of edema, you must immediately call the SAMU by dialing 15.

The allergens involved

  • Animals
  • Latex (condoms, gloves or medical instruments, shoe soles, bathing caps …)
  • Colorful flowers or bulb plants
  • Some medicines
  • Some beauty products

Although few cases of urticaria or angioedema are allergic in origin, they must be diagnosed because they represent a potentially serious risk.

The urticaria can be chronic and settle for several weeks, months or years, in this case, it is almost never of allergic origin but a balance is necessary. The problem is usually controlled by medication.

5 %

Only 5% of urticaria attacks or angioedema are of allergic origin

[1] Bieber T, Atopic Dermatitis. New Engl J Med. 2008; 358: 1483-1493