Contact dermatitis occurs when your skin reacts to a particular substance, which can either be an irritant or an allergen.
Allergic contact dermatitis
Allergic contact dermatitis occurs when you come into contact with an allergen which your body becomes sensitised to. When you touch that substance again, your skin reacts with an itchy red rash (dermatitis).
You develop a rash because your immune system reacts abnormally to the allergen. Your immune system usually protects your body against infection and illness, but during an allergic reaction, it can attack healthy cells and tissue as well. This is what causes your skin to be sore and inflamed.
Common allergens which can trigger allergic contact dermatitis are listed below.
- Metals - such as nickel, or cobalt, in jewellery.
- Cosmetics - such as fragrances, hair dye, and nail varnish.
- Rubber - including latex.
- Textiles - particularly the dyes and resins that are contained in them.
- Strong adhesives - such as epoxy resin adhesives.
- Some plants - such as chrysanthemums, daffodils, tulips, and primula.
- Some medicinal creams that are applied directly to the skin - topical medications, such as steroid cream.
Irritant contact dermatitis
Irritant contact dermatitis occurs when your body comes into contact with an irritant. Your skin is damaged by the irritant, which causes a burning and stinging sensation, as well as the other symptoms of reddening and soreness.
Your irritant contact dermatitis may be caused by frequent exposure to a weak irritant, or it may occur after a single exposure to a stronger irritant.
Irritant contact dermatitis can occur in anybody who is exposed to irritants for a sufficient duration of time.
Common irritants include:
- detergents and soaps,
- perfumes and preservatives in toiletries or cosmetics,
- solvents and abrasives,
- oils,
- acids and alkalis,
- cement
- powders,
- water (especially hard, chalky or heavily chlorinated water),
- dust,
- soil, and
- some plants (such as anemone, clematic, ranunculus, hellebrous and mustards).
If you work with irritants as part of your job, you may be more at risk of developing irritant contact dermatitis. There are some jobs where this type of dermatitis is more common. They include:
- cleaning and housekeeping,
- food preparation and catering,
- hairdressing,
- agriculture and fishing,
- engineering and construction,
- medical, dentistry and veterinary, and
- printing and painting.
Other factors
If you already have contact dermatitis symptoms, there are a number of other factors which can worsen your existing symptoms. These include:
- heat,
- cold,
- friction, and
- low humidity (dry air).
If you have irritant contact dermatitis, you are more at risk from these factors than if you have allergic contact dermatitis.
