Contact Dermatitis

Patches of red, itchy, and flaking skin caused by irritation or allergy

  • Work involving exposure to chemicals or detergents is a risk factor
  • Age, gender, and genetics are not significant factors

As its name implies, contact dermatitis is inflammation of the skin caused by contact with a specific substance. There are two types: irritant contact dermatitis, which is caused by primary irritants (substances, such as bleach, that harm anyone’s skin); and allergic contact dermatitis, which occurs when a person comes into contact with a particular substance to which he or she has developed a sensitivity over time.

Substances that commonly trigger irritation or allergic reactions include some cosmetics; the nickel contained in jewellery, buttons, earrings for pierced ears, watch straps, and jean studs; certain chemicals; drugs in some skin creams; and certain plants, such as ragweed and primula.

What are the symptoms?

Contact dermatitis usually affects only the area that has been in direct contact with the substance that triggered the reaction. In irritant contact dermatitis, the skin inflammation develops soon after contact with the substance. The severity of the resulting rash depends both on the concentration of the irritant and on the duration of exposure.

Allergic contact dermatitis usually develops slowly over a period of time, and it is possible to have contact with a substance for several years without any skin inflammation occurring. However, once your skin has become sensitive to the substance, even a small amount of it or a short exposure time can trigger an allergic reaction.

In either form of contact dermatitis, the symptoms may include:

  • Redness and swelling of the skin.

  • Water- or pus-filled blisters that may ooze, drain, or become encrusted.

  • Flaking skin, which may develop into raw patches.

  • Persistent itching.

Consult your doctor if the cause of the contact dermatitis is not obvious or if the inflammation persists for a longer period of time than usual.

What might be done?

Your doctor will want to know when the skin inflammation developed and whether you have any known allergies. The site of the reaction is often a clue to its cause. For example, a patch of dermatitis on the wrist may be caused by an allergy to nickel in a watch or watch strap. People who handle chemicals at work often develop irritant or allergic contact dermatitis on their hands.

Your doctor may prescribe a topical corticosteroid to relieve itching and inflammation. However, even with treatment, contact dermatitis may take a few weeks to clear up.

If you handle chemicals at work, it is particularly important to find the cause of your skin allergy. If the cause cannot easily be identified, you may need to have patch testing.

Once the trigger has been identified, try to avoid it as much as possible. If you cannot do so, you may need to cover your skin with creams (see Emollients and barrier preparations), protective clothing, or gloves before you are exposed to the trigger.

Test: Patch Testing

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.

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