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CONTACT DERMATITIS

What is Contact Dermatitis ?

Contact dermatitis is a form of eczema. It is triggered by contact of the skin with a substance to which the skin has become allergic. It is restricted to that area which has come into contact with the substance. A red itchy rash develops, with small blisters in the most inflamed parts. The rash will come up every time the skin is brought into contact with that substance. With irritant contact will last for 24 hours or so and with allergic contact will last up to a week after contact has been withdrawn.

How does Contact Dermatitis occur ?

In irritant dermatitis, the skin will react to the substance the first time it comes in contact with it. The reaction will start as soon as the contact with the skin has been made. In allergic eczema, the skin first needs to become sensitized to the substance. This usually requires multiple contacts over a period of months or even years. Eventually the defence or immune system within the skin recognizes the substance as being foreign. It then starts an “immune response” to it. This reaction generally starts 48 to 72 hours after contact with the substance and may persist for up to one week, depending upon the substance involved. Once the skin is sensitized to that substance, only tiny quantities of the substance are needed to induce a response.

Why does Contact Dermatitis occur ?

In irritant dermatitis, the substance is usually irritant to different degrees in different people. Some may develop a florid reaction to it while others will develop a subtle reaction to it. The irritant works directly on the skin, damaging it by being a strong detergent, solvent, alkali or acid and will induce an immediate response in the skin. People may become allergic to a vast array of different substances or chemicals. The most common are metals (especially nickel and cobalt), preservatives, resins, and chemicals used in rubber, oils, dyes and perfumes. Cosmetics, jewellery and rubber gloves are just some of the everyday items which can act as triggers.

Treatment Involved for Contact Dermatitis

The first step involves finding out what the culprit (or allergen) is. This is done by patch testing. Small aluminium discs containing test substances will be stuck on to your back. In most specialist centres, a standard set of common allergens is used. A more extensive range of allergens is available for further testing. If a particular substance is suspected (such as a hair dye, hair spray, or cosmetic), this can be included in the patch tests. The discs are held on with paper tape and left undisturbed for 48 hours. It is important not to scratch the skin or remove the discs during that time. At the end of the 48 hours, the discs are removed and the back is examined for evidence of dermatitis. Examination is repeated at 72 hours, at which time irritant reactions will have subsided but allergic reactions will still be active. Examination at this time is also necessary as some people may show a delayed response. Once the allergen has been identified, you will be provided with a list of substances that may contain that allergen. It is important to try to avoid these as much as possible. This may even call for changing jobs. Subsequent contact with the allergen will invariably result in the eczema developing at the site of contact. The eczema itself will respond to steroid (cortisone-like) creams. These should always be used in combination with a soap substitute such as emulsifying ointment or aqueous cream. This will help to moisturize the skin and prevent the drying effect of the steroid creams.

During Treatment for Contact Dermatitis

Once the allergen has been withdrawn, the eczema will respond very quickly to the steroid preparation. It should settle within a period of a week. Each time the allergen is brought into contact with the skin, however, the eczema will develop again. In circumstances where there is continuous exposure to an allergen, the cream will tend to limit the symptoms of the eczema but will never completely clear it.

After Treatment for Contact Dermatitis

If not appropriately managed by avoidance of the allergen or using steroid cream, the condition would gradually become worse. Acute eczema becomes chronic. Because of scratching, open skin could become infected. The allergen could also spread to other areas of the body and the eczema would become very widespread.