Allergic reactions

Allergic Reactions

Atopic dermatitis

Eczema or Neurodermatitis

A skin disorder involving hypersensitivity (allergy - related) reaction within the skin characterized by inflammation, itching, and scaling. See also lichen simplex chronicus.

Causes, Incidence and Risk Factors

Atopic dermatitis can occur in an infantile (children) or adult form. It is most common in infants, and at least half of those cases clear up by age 18 months. This is often a family history of asthma, hay fever, eczema, psoriasis, or other allergy-related disorders. In adults, it is generally a chronic or reoccurring condition.

Neurodermatitis is a form of atopic dermatitis characterized by a self-perpetuating scratch-itch cycle. Although symptoms increase in times of stress, physiological changes in the nerve fibers are also present.

A hypersensitivity reaction (similar to an allergy) occurs in the skin, causing chronic inflammation. The inflammation causes the skin to become itchy and scaly. Chronic irritation and scratching can cause the skin to thicken and become leathery-textured, although this is more pronounced in the localized form, lichen simplex chronicus.

Exposure to environmental irritants can worsen symptoms, as can dryness of the skin, exposure to water, temperature changes, and stress.



intense itching


blisters (vesicle formation) with oozing and crusting


skin redness or inflammation around the blisters


rash, in child under 2 years old


skin lesions begin on the cheeks in infants


may progress to the scalp, arms, trunk, and legs


dry, leathery skin areas (lichenification)


more or less pigment than their normal skin tone (see skin, abnormally dark or light)


located commonly in the inner elbow or behind the knee


may spread to the neck, hands, feet, eyelids, or behind the knee


raw areas (excoriation) of the skin--from scratching


ear discharges/bleeding

Signs And Tests

Diagnosis is primarily based on the appearance of the skin and on personal and family history. The health care provider should examine the lesions to rule out other possible causes. A skin lesion biopsy may be performed, but is not always required to make the diagnosis.

This disease may also alter the results of an eosinophil count - absolute test.


Consult your health care provider for diagnosis of atopic dermatitis, because it can be difficult to differentiate from other skin disorders. Treatment should be guided by the health care provider. The goal of treatment is reduction of symptoms.

Treatment may vary depending on the appearance (stage) of the lesions--acute weeping lesions, dry scaly lesions, or chronic dry thickened lesions are each treated differently.

Infantile eczema usually becomes milder with age and often disappears after age 3 or 4. Atopic dermatitis usually responds to home treatment. Treatment is designed around the chronic nature of the disease. Anything that aggravates the symptoms should be avoided whenever possible, including any food allergens and environmental irritants such as wool and lanolin. Dry skin often makes the condition worse, so bathing and the use of soaps may be reduced. Temperature changes and stress may cause sweating and changes in the blood vessels of the skin, also aggravating the condition.

If avoidance of irritants does not reduce symptoms, treatment applied to a localized area of the skin (topical) may be indicated. Topical treatment of weeping lesions may include soothing lotions, mild soaps, or wet dressings. Mild antipruritic lotions or topical steroids (see corticosteroids-topical-low potency) may soothe less acute or healing areas, or dry scaly lesions. Chronic thickened areas may be treated with ointments or creams that contain tar compounds, topical steroids (see corticosteroids-topical-medium to very high potency), ingredients that lubricate or soften the skin, or other ingredients. Systemic corticosteroids may be prescribed to reduce inflammation in some severe cases.

Expectations (Prognosis)

Atopic dermatitis is a chronic condition, but it may be controlled with treatment and avoidance of irritants.



Secondary bacterial infections of the skin


Permanent scar formation

Calling Your Health Care Provider

Call for an appointment if atopic dermatitis does not respond to avoidance of allergens, if symptoms worsen or treatment is ineffective, or if signs of infection (such as fever, redness, pain) occur.


No known prevention. The condition tends to run in families. Control of stress and emotional conditions (nervousness, anxiety, depression, etc.) can be beneficial in some cases.