There are three major forms of skin diseases caused by allergies.
1. Infantile eczema also known as atopic dermatitis, is considered an allergic disorder for the following reasons:
- Many infants with this syndrome also develop allergic rhinitis and asthma later in life.
- In many cases the rash appears to be an allergic response to certain foods, especially egg white, milk, wheat, and corn. However, inhaling or direct skin contact with other allergens such as dust mites may also be involved.
- Infants and children with eczema are very prone to itching; the ongoing scratching that results plays an important role in perpetuating the rash.(Eczema has sometimes been called “the itch that rashes.”)
Eczema usually develops when the child is two to six months old and may wax and wane over the next several months, often disappearing completely by the age of three. In some individuals this condition persists into later childhood or even adulthood. The rash of eczema is patchy, dry, slightly reddened, and very itchy. Intense scratching of the affected skin may lead to oozing, deep scratch marks called excoriations, bleeding, and infection. Irritation of the skin from chronic scratching may cause the formation of thickened plaques, a process called lichenification. During infancy, eczema often appears on the cheeks, scalp, neck, back of the arms, front of the legs, and the upper body. In an older child, the rash is commonly seen in the creases of the knees, el-bows, neck, wrists, and face.
While foods and other allergens play a role in eczema, environmental factors also affect the skin. Cold, dry air causes the skin to become dry and scaly, while a hot, humid climate induces sweating, which may increase scratching. Skin irritants such as rough clothing, soaps, detergents, and fabric softeners can also worsen eczema. A number of measures can help an infant or child with eczema. Try to maintain a stable temperature and humidity within the home. A child’s skin should be protected from excessive dryness, which provokes itching and scratching. Because prolonged contact with water (especially very hot water) may actually dry the skin, use comfortably warm water for baths or showers and keep them short. Use a nonirritating brand of soap and pat lubricating oil on the affected skin while the skin is still damp. Moisturizing skin creams and softeners should be applied daily. Cotton clothing is preferable to wool, silk, and nylon. Clothes should be washed with a mild deter-gent and rinsed twice.
Check with your child’s physician for recommendations regarding appropriate soaps and skin moisturizers for your child’s age and skin condition. The physician may also recommend that a topical steroid preparation be applied to the most severely affected areas of skin. These can dramatically improve local inflammation and itching, but they should be used only as directed. Time limitations on the use of steroids – and the selection of the mildest form that will improve the rash – will help prevent steroid-induced local skin changes. An antihistamine such as diphenhydramine (Benadryl) may help prevent scratching at night, and keeping fingernails short will help prevent further irritation. Specific foods that are clearly linked to a child’s eczema eruptions can be avoided, but determining which ones might actually be involved is usually not easy. Severe dietary restrictions are unlikely to help eczema. If you are concerned about the number of foods that may be provoking a child’s rashes, see a qualified allergist.
2. Contact dermatitis occurs when a substance that touches the skin causes local allergic reaction. The most familiar form of contact dermatitis is the eruption caused by poison ivy, oak, or sumac. Other potential causes of contact dermatitis include cosmetics, soaps, detergents, perfumes, dyes used in fabrics, rubber, metal (especially nickel, sometimes a component of jewelry or wristwatch casings), topical medications, and com-pounds used in the preparation of leather. Several days of exposure might be needed to provoke a reaction, but once a child is sensitized, a rash could appear within 24to 48 hours after contact.
Usually the shape and distribution of the rash will suggest contact dermatitis to a parent or physician. Treatment involves, first and foremost, avoiding the irritating sub-stances. A local eruption will usually respond to a topical steroid preparation, but in more extensive outbreaks (such as with poison oak or ivy) oral steroids may be pre-scribed for several days. Antihistamines such as diphenhydramine (Benadryl) sometimes help reduce itching. Hives (also called urticaria), are a generalized allergic response involving raised, reddened, irregular itchy patches of skin that may blanch(turn white) when pressure is applied. They vary from dime-size to much larger areas of skin, and they constantly change size and location. When hives affect the deeper layers of the skin, the eruption is called angioedema, a change that can develop anywhere on the body but most commonly affects the ‘mouth, eyes, tongue, genitals, and extremities.
3. Hives can last from minutes to days and may even re-cur in crops for weeks and months. An impressive number of allergens cause hives, and identifying the specific agent is sometimes quite difficult. Some possible causes and/or triggers of hives include the following:
- Foods such as milk, eggs, peanuts, berries, shell-fish, and nuts
- Medications such as penicillin, sulfa drugs, and aspirin
- A variety of infections, including those caused by viruses (such as hepatitis or infectious mono-nucleosis), bacteria, fungi, and parasites
- Inhaled substances such as pollens, dust, and animal danders
- Physical events such as exposure to cold, heat, local pressure, vibration, and exercise
- Insect bites
If hives are a recurring problem or last for more than a few days, keeping track of foods, symptoms, or other events (including where the child has been) prey their arrival could be useful. Skin testing is occasionally helpful. If there is a clear relationship to a specific or drug, the provoking agent should he avoided if you child’s doctor and any others who care for him in should be notified of a suspected drug reactive most cases, hives can be controlled with antihistamines such as diphenhydramine (Benadryl and others) .Unless there is an underling disease causing them, hives do not lead to problems and will disappear without complications. If there is difficulty breathing, or feeling faint, the child should be taken to the nearest emergency facility immediately. If a child has an extremely severe reaction to a particular drug, attend the physician. Whenever any prescription is written and to be filled, as an extra safeguard, mention the reaction to the pharmacist when having it filled. If a child has ever has an immediate and serious allergic reaction, ask a physician about obtaining a kit containing epinephrine (adrenaline) for emergency use.