A number of chemical or herbal substances can irritate the skin. Redness, burning or itching are normal skin reactions, for instance, to aggressive cleaning agents.
Allergic contact dermatitis (sometimes simply called “contact allergies”) is different, though. Here the immune system overreacts to certain substances – sometimes to very small amounts – that normally wouldn’t cause a reaction. Common examples include certain metals, scents and latex rubber.
Contact allergies can lead to severe skin reactions. Unlike with many other kinds of allergies, the reaction doesn’t occur immediately, but after one to three days. And contact allergies develop gradually over a long period of time, as a result of repeated contact with the substance that triggers them. Some people are then no longer able to carry on doing the same kind of work as before.
Contact allergies cause eczema (dermatitis). The typical symptoms include:
- a red rash, often without clearly defined edges,
- itching, and
- dry skin.
In severe allergic reactions, the skin may hurt and feel tight. Blisters might form as well. If the blisters burst, the skin “weeps” (oozes a fluid), scabs form and then flake off.
At first, the symptoms affect only the area of the body that comes into contact with the trigger. This is often the hands, particularly the fingers and backs of the hands. Other areas that are often affected include the face (especially the eyelids and lips), the neck, lower legs and feet. The severity of the allergic skin reaction will mainly depend on which substance the skin came into contact with, and for how long.
In contact allergies, allergic reactions can also later occur in other parts of the body that didn’t come into contact with the allergen (trigger).
Substances that commonly trigger contact allergies include the following:
- Metals (e.g. nickel and cobalt)
- Latex rubber
- Adhesives (e.g. the sticky substances in plasters)
- Plants (e.g. chamomile and arnica)
- Scents (in cosmetics such as lipsticks, perfumes and soaps)
- Cleaning agents and solvents
- Essential oils
- Medications that are applied to the skin
The body already makes antibodies to fight the trigger (allergen) the first time it comes into contact with it. This makes the skin react more sensitively to the substance when it comes into contact with it again. Noticeable symptoms only start appearing over time, after repeated contact with the substance. For instance, hairdressers may develop contact allergies to substances that they come into contact with every day, such as hair dyes or perm solutions. Some people are generally more prone to allergies. They may develop contact allergies in a shorter amount of time.
About 8% of all adults have a contact allergy. They are more common in women than in men. Contact allergies are responsible for 10% of all occupational (work-related) diseases. They commonly affect hairdressers, beauticians, nursing staff, bakers, office workers, metalworkers and bricklayers.
Contact allergies usually first arise in adulthood. The symptoms often go away if they are treated and the triggers are avoided. But contact allergies might also develop into chronic contact dermatitis. The skin then becomes thick and hard, with painful cracks.
It isn’t possible to determine whether or not someone has a contact allergy based on the symptoms alone. But allergic rashes are often a bit different from rashes that are caused by other things. For instance, severe itching and a rash without clearly defined edges are more likely to be signs of an allergic reaction. And allergic rashes often occur in various parts of the body.
The doctor will ask you which substances you came into contact with in the days before the symptoms appeared, and whether you have been repeatedly exposed to certain substances in the past. A patch test can be done to find out whether it is actually an allergic reaction. This involves placing the substance on your skin with the help of a patch which is stuck on your back for one to two days. If a rash appears where the patch was, you are probably allergic to that substance. Patch tests may actually lead to the development of contact allergies, though. So it’s all the more important that the doctor is well informed about contact allergies and is careful when choosing which substances to use in the test.
Allergic skin reactions are usually treated with steroid creams, ointments or solutions.
But the main thing to do is avoid contact with the substance that triggers the reaction. Protective gloves and clothing can help here, for instance.
A change of career may have to be considered if it isn’t possible to avoid contact with the substance in the workplace. If you are believed to have a work-related contact allergy, it’s a good idea to have your doctor inform your employer’s liability insurance. The insurance will cover certain costs, like the costs of protective measures, if the allergy is recognized as being work-related.
Biedermann T, Heppt W, Renz H, Röcken M (Ed). Allergologie. Berlin: Springer; 2016.
Brasch J, Becker D, Aberer W, Bircher A et al. Leitlinie Kontaktekzem: AWMF-Register-Nr.: 013 - 055. Allergo J Int 2014; 23: 126.
Diepgen TL, Ofenloch RF, Bruze M, Bertuccio P, Cazzaniga S, Coenraads PJ et al. Prevalence of contact allergy in the general population in different European regions. Br J Dermatol 2016; 174(2): 319-329.
Fonacier L, Bernstein DI, Pacheco K, Holness DL, Blessing-Moore J, Khan D et al. Contact dermatitis: a practice parameter-update 2015. J Allergy Clin Immunol Pract 2015; 3(3 Suppl): S1-39.
Rashid RS, Shim TN. Contact dermatitis. BMJ 2016; 353: i3299.
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