Over the years, atopy (from the Greek atopia, for "uncom-monness") has been given various meanings. Broadly, it is a group of allergic diseases—mainly allergic rhinitis, allergic asthma, and some forms of eczema—that have some characteristics in common. Among these characteristics are a frequent, positive family history of similar allergic illnesses and the presence of increased serum levels of allergic antibodies to such common environmental allergens as pollen, molds, house dust, and animal danders. The most common feature of atopy in atopic patients is the tendency to develop allergic antibodies to common inhalant substances as a result of natural ex­posure. This tendency is now believed to be genetically determined.

As is true of other corticosteroids, adverse effects depend on the potency, concentration, and frequency and duration of use. Ophthalmic steroid preparations should be avoided in eye infections. Common adverse effects are discomfort and a burning sensation, sometimes accompanied by watery eyes, dilated pupils, blurring of near vision, and drooped eyelids. The bloodstream absorbs enough corticosteroid to cause partial adrenal suppression in adults and, with prolonged use in children, the de­velopment of systemic side effects. Prolonged use of corticosteroids may increase pressure within the eyes and eventually damage the optic nerve, as well as lead to cata­racts and, rarely, inflammation of various parts of the eyes. Summary The drugs used in treating allergic disorders are considered among the safest in medicine, even though these drugs can have minor side effects, for example, nausea, drowsiness, and nervousness. The more serious side effects occur only rarely, and are usually reversible by discontinuing the drug being used or by reducing the dosage. No drag produces only the precise effect desired; all drugs have various effects. Undesirable effects —called side effects, adverse effects, or secondary effects—become acceptable if the potential therapeutic benefit is suf­ficient. The potential benefits may be maximized and the risks mini­mized if drugs are taken as directed by one’s physician.

Anyone with a tendency to allergy generally c an be, or become, sensitive to one or more foods. The tendency to allergy is inherited it can show up in any symptoms of allergy, and any substance са n become the sensitizer, including foods. A child has a 75 регсе nt chance of developing an allergy at an early age if both his parents are allergic. Although food allergy can occur at just about any age, it is most likely to appear during infancy. As children grow older, their food allergies often change; such children may develop an allergy to a new food, or lose an existing allergy. Most food allergies, however are outgrown.

The rebound phenomenon is an allergy con­dition in which prolonged use of a drug or drugs (such as nasal vaso­constrictor sprays for hay fever treatment) creates a need for more and more of the drug(s), while the desired effect steadily decreases.

The condition known as laryngeal edema is usually part of the multiple involvement of anaphylaxis; occasionally, it may be the sole reaction to a food, drug, or sting. The best remedy is to inject epi­nephrine, as described above; the next best thing to do is inhale two doses from an epinephrine aerosol, supplemented by oral antihista­mine tablets. Normally, the condition improves within minutes; if it does not, suffocation, cyanosis (bluish skin caused by lack of air), and loss of consciousness will occur. If the throat or the lower windpipe remains closed despite self-medication, medical attention should be sought immediately. During the approximately five minutes available before permanent damage results from lack of oxygen, a surgical procedure known as a tracheotomy must be performed. The procedure consists of making an opening in the windpipe below the obstructed area, to allow oxygen to enter the lungs. Another medical procedure, called cardiopulmonary resuscitation, is sometimes used, but the procedure is not effective if air cannot be forced through the ob­structed windpipe. Asthma The injection of epinephrine is, with only a few exceptions, the treatment of choice. Alternatives should be sought if an epinephrine or epinephrine-type aerosol has been inhaled four or more times within the preceding hour, or if the heartbeat is extremely fast and irregular. (A fast but regular heartbeat, or a moderate increase in high blood pressure, should not deter one from injecting epinephrine if an asthma attack is becoming more severe.) If prescribed drugs have not been taken up to the dosage level allowed, they should be taken to that level before resorting to injections. Two tablets of Tedral, Marax, or a similar combination drug can be tolerated without serious side effects in an otherwise healthy adult with a severe asthma attack. Similarly, the following drugs may be taken safely: up to two tablets of metaproterenol (Alupent and Metaprel), 10 milligrams each; terbutaline (Bricanyl and Brethine), 5 milligrams each; or one of the standard (not long-acting) theophylline preparations, up to 250 milligrams. Depending on someone’s prior experience, he or she may be able to tolerate single doses of both the adrenergic and the theophylline drugs taken together. If nausea or vomiting precludes oral therapy, an inhaled or injected bronchodilator is the next treatment. An acute asthma attack is not the time for treatment with inhaled cromolyn (Intal) or beclomethasone (Vanceril and Beclovent); these are designed for prevention. A person regularly taking prescribed steroid drugs such as prednisone, who has omitted one or more doses, should take the amount missed immediately. Many physicians prescribe extra doses of steroids in treating attacks of asthma that are increasing in severity. Consult your physician ahead of time about what you should do in case of worsening asthma or for a sudden, severe attack in cases where medical attention is not readily available. It is most important that you become familiar with all asthma medication. Know the name, amount (usually given in milligrams, abbreviated "mg" if in tablet or capsule form, and "mg per ml" if liquid), and frequency of dosage. It is equally important that you regularly monitor medication to ensure an adequate supply, and that the expiration date printed on the label has not passed. Keep medi- f cations only in clearly labeled containers —with names, directions for use, and expiration dates. Because one occasionally forgets, the location and business hours of the nearest pharmacy should be kept » handy. Prevention is still the most effective treatment for asthma. Try to anticipate when and where asthma will be aggravated, so you can take measures to avoid these times and places and increase medica­tion. Because asthma can get out of control fairly rapidly, you should not ignore attacks that are worsening; neither should you test the limit of your tolerance. You should, of course, avoid anything that can aggravate asthma. The careful asthma victim will fully and quickly treat an attack with prescribed medication, thus avoiding in most cases, discomfort, emergency room treatment, and hospital­ization. Skin Reactions Eczema and contact dermatitis are lesions that have become in­flamed. In the early stages of inflammation, the lesions should be cleaned carefully with cool water, baking soda or cornstarch soaks, or with a nonperfumed lotion. Avoid excessive exposure to water, heavy ointments, and heat, since these tend to smother the skin and cause it to dry out, thus adding to the inflammation. A solution or lotion containing steroids for the skin usually speeds the healing process. These preparations are usually prescription items. Avoid using antibiotic or antihistamine creams, which can increase the sen­sitivity. If itching is a problem —as it often is—the best relief is through the use of oral antihistamines. In the late stages of eczema, the skin becomes tender, swollen, and less red while some scaling of tissue occurs. The itchy scales can be removed with a cotton swab moistened with olive or mineral oil. Lotions may be changed to creams, particularly those containing steroids. If the itching continues, antihistamines should be taken every six to eight hours. In cases that do not respond to this treat­ment, healing is usually aided by steroids taken orally or by injection. Such therapy, however, must be supervised by a physician. Prevention is important in this group of skin diseases. The allergens involved can often be identified, and should be carefully avoided. The most common allergens that cause eczema are foods such as milk and other dairy products (infants are particularly sensitive), eggs, oranges, and wheat products. Contact dermatitis is caused by the resins of such plants as poison ivy, poison oak, sumac, primrose, and ragweed, as well as by chemicals in cosmetics, clothing, shoes, and jewelry. Hives can be provoked by drugs, especially penicillin, aspirin, codeine, and certain foods. Other causes of hives are para­sitic worm infections and insect stings. Some people develop hives from physical pressure on the skin or from extremes of hot or cold. Although the causes of many forms of eczema and hives are not yet known, you should make a concerted effort to identify the causes, and thus prevent a recurrence. People suffering from colds, skin infections, chicken pox, or herpes viral infections should be avoided, since their organisms can contaminate allergic dermatitis. Because hives are often generalized, and the skin covering them is intact, the use of skin preparations will have less effect than when they are used for eczema or contact dermatitis. Itching and swelling usually respond well to oral antihistamines. Ephedrine, an adren­ergic drug available in 25-milligram doses without prescription, is used to reduce the swelling. If hives increase, and if angioedema is severe, injectable epinephrine should be taken. A dose of 0.2 to 0.3 milliliter of epinephrine 1:1,000 injected subcutaneously, as in asthma or anaphylaxis, is recommended.

The RAST (for radioallergosorbent test) is used to detect and measure allergic antibodies against an antigen in a person’s serum. It is more specific than skin tests but is less sensitive and more ex­pensive. Currently it is being used in certain patients for whom skin tests are technically difficult, such as those with severe skin diseases and young children or infants.

An ingestant allergen is a substance that causes an allergic reaction when eaten or swallowed—for example, eggs, milk, aspirin, or penicillin.

Allergic children are predisposed to allergies to new substances. A casual encounter, such as visiting friends who have a pet, may not be enough to sensitize a child; but continued, massive exposure to an animal will often do so. Unfortunately, this sensitization frequently takes one to two years, which means that the new allergy becomes evident just as the pet becomes an integral part of the family, and just when separation is the most traumatic. The best advice is simply not iave a dog, cat, or other fur-bearing animal in a home where a ily member is allergic. Some pets that are safe for allergic farn-i are tropical fish, turtles, chameleons, iguanas, and snakes.

Atopic means having an inherited tendency to suffer from allergic diseases.

Eczema is an inflammation of the skin, marked by redness, itching, and scales.