Allergic dermatitis or skin reaction to certain substances

Symptoms and signs of most allergic reactions are present in the skin. In allergic patients with cutaneous manifestations, two types of lesions are observed, mainly urticaria, which is formed by wheals and itching and in many cases is not due to allergic reactions; and eczema, where we find vesicles or small pimples and is associated with desquamation.

Eczema is observed in contact dermatitis or allergic dermatitis. This is an inflammation of the skin caused by direct contact with a substance, as, for example, in allergies to costume jewelry. Eczema can also be seen in atopic dermatitis, where the lesions have a typical distribution according to the age of the patient, being more frequent in children and adolescents. Atopic dermatitis is a manifestation usually related to allergic patients.

Allergic contact dermatitis

Contact dermatitis may be produced by an irritant substance, which is the most common cause, and inflammation resulting from contact may be due to contact with acids, alkaline materials such as soaps and detergents, solvents or other chemicals. The typical lesion is a burn and the onset is usually immediate.

Allergic contact dermatitis, on the other hand, is caused by exposure to a substance to which the patient has become sensitized and to which he or she is allergic. The reaction may appear several hours or even days after contact, and manifests itself in the form of reddened and swollen skin which, within hours, develops into small vesicles with fluid inside. Subsequently, the vesicles rupture and a sticky liquid flows out, forming crusts.

When lesions of allergic contact dermatitis are prolonged over time, the skin appears reddened and shiny and subsequently flakes, and may eventually form a thickened, dry, lichenified skin.

Unlike eczema, in urticaria the wheal-like lesions tend to disappear within several hours and leave no residual lesion on the skin.

Read Now 👉  Most food allergies are lifelong manifestations

Causes of allergic dermatitis

There are multiple causes of allergic contact dermatitis. The most frequent are nickel and cobalt, present in costume jewelry, watches or belts; balsam of Peru, found in some cosmetics; antibiotics and local anesthetics, applied to the skin, such as neomycin; fragrances of some colognes; formaldehyde, used as a preservative in industry and the home; preservatives found in cosmetics and paints; para-phenylenediamine, ammonia and other substances used for hair dyeing, among many other products.

Diagnostic tests for allergic dermatitis

Based on skin lesions and history of exposure to irritants or allergens, the diagnosis of contact dermatitis may be suspected.

Allergic testing with skin patches containing the suspected substances of the patient’s exposure helps to pinpoint the allergen responsible for allergic contact dermatitis.

Treatment of allergic dermatitis

To treat allergic dermatitis, exposure to the substance responsible for the dermatitis should be removed and future exposure should be avoided. If the cause is secondary to occupational exposure, a change of workplace will be necessary. If the substance is in the body, it should be evaluated to remove it as far as possible.

For the prevention of future exposures it is necessary to use protective gloves and barrier creams, if exposure to the allergic substance is unavoidable.

For the treatment of lesions, experts in Allergology recommend washing and care to remove the irritating substances that have remained on the skin. In addition, creams should be used to reduce inflammation. In cases of severe lesions, antihistamines and even oral corticosteroids should be used.