The occasional skin reaction to a drug or plant, the last in this group of allergy emergencies, can become so extensive that it poses a real danger. Poison ivy or oak may produce such a skin reaction. The skin may blister. Intact skin protects against bacteria and allows the exchange of salts and water needed to prevent the body from overheating. If enough skin is involved, the victim risks complications from the partial loss of skin. If damage to the skin is extensive enough, fever, chills, skin abscesses, and blood-borne infections may occur. The skin inflammation (dermatitis) that results from contact with poison ivy, cosmetics, metals, or chemicals is called, appropriately, contact dermatitis; antibodies are not involved. Cells called lympho­cytes become sensitized to the chemicals and, upon reexposure to the chemicals, enter the skin in an effort to remove the invading material. In the ensuing effort, the lymphocytes call in helper cells —macro­phages. Macrophages, literally "big eaters," may damage normal tissue in the process of clearing up the invaders. It generally takes about forty-eight hours after the chemical enters and the cells re­spond for skin damage to be visible. An even more severe dermatitis may result —not from external contact this time, but from drugs taken internally. Some of the earlier, long-acting sulfa preparations were responsible for such severe blistering that large areas of the skin were shed, a condition physicians call exfoliative dermatitis. Today, few of the drugs com­monly used cause such reactions. It is always possible, however, that a new drug will be approved before an adverse reaction is discovered. Severe anaphylaxis, unremitting asthma, acute edema of the larynx, and extensive contact (or exfoliative) dermatitis must all be considered true emergencies. Emergencies, though, may also arise from the side effects of the drugs used to treat these and other allergic diseases. Serious side effects are usually due to a relative over­dose of a drug. The overdose may be caused not only by receiving or taking more than the usually prescribed amount but because of the body’s metabolism of the particular drug or because the excretion is slower than normal. The end result is an accumulation of high or toxic levels of the drug or drugs. Among antiallergy drugs, the bronchodilators used to treat asthma cause the bulk of serious side effects. (A list of undesirable reactions appears in Table 3.3.) Nonemergency Allergic Reactions The conditions described below are more annoying than danger­ous. Familiarity with their symptoms and causes should alleviate alarm and lead to proper treatment.

Two conditions constitute an emergency in this category—laryngeal edema and asthma. Swelling of the windpipe, or laryngeal edema, is the most immediately life-threatening. The victim literally feels a lump in the throat, followed by a sensation of constriction and difficulty absorb­ing air, and produces a high-pitched, crowing sound. In other areas of the body, this swelling may be accompanied by hives or edema, or, as mentioned, it may be a manifestation of anaphylaxis. Such drugs as penicillin and its derivatives, and such foods as nuts and shellfish, are among the more common allergic causes. Insect stings, especially on the neck or face, may also be responsible. Variant Diagnosis Anything that can block the windpipe can cause similar symptoms. This includes foreign bodies that enter the respiratory tract instead of the esophagus, infections that cause in­flammation in the throat or the larynx, and tumors in these areas. An asthma attack that is not relieved eventually becomes an emergency. A person with asthma cannot circulate air normally through the bronchial tubes. As these tubes become more con­stricted —due to contraction of their interlacing mutfcle, edema of their inner lining, or excess local production of mucus, among other factors—-the asthma victim works harder and harder to breathe. The initial wheezing becomes louder, exhalation lasts longer, air is trapped inside, and the chest wall expands. The patient is forced to sit up with shoulders hunched forward. It becomes difficult to cough up the thickened mucus, and breathing becomes more and more labored. The symptoms of a serious asthma attack are: 1. An attack that does not improve after several hours have passed. 2. Wheezing that becomes louder and then stops, despite extremely labored breathing. 3. Increasing fatigue and weakness. 4. Pulse rate greater than 160 beats per minute in children under six, greater than 140 in others; or irregular rhythm. 5. Bulging of the neck muscles, an expanded chest cage, and deepening of the notch over the breastbone. Fever is not a prominent factor in any of the emergency situations described thus far. If the asthma is complicated by an infection, the temperature usually exceeds 100°F(39°C). Asthma also may be provoked by a viral respiratory infection such as influenza, in which case the patient suffers from both condi­tions. Asthma may also lead to pneumonia, a condition that may arise in a lung deprived of its normal oxygen supply by bronchial tubes obstructed by mucous plugs. In some cases, a relatively com­mon airborne fungus spore grows in the air passages. An allergic reaction to the fungus produces inflammation that, in turn, causes a febrile bronchitis, or pneumonia. In medicine, this fungus is called aspergillus, and the complication, allergic bronchopulmonary asper­gillosis. If coughing is violent and prolonged, the opposing forces of chest muscles and rib muscles can cause a rib to fracture. Usually the rib does not break sufficiently to puncture the lungs, but the fractured rib can cause sharp chest pain. Coughing can also rupture air sacs in the lungs. The escaping air moves upward under the heart lining and the lung tissues. Trapped air causes a dull pain in the chest, or a sharp pain if part of a lung collapses under the pressure of trapped air (a condition known as pneumothorax). Often the air simply rises under the linings of the bronchial tubes to the trachea and stops in spaces beneath the soft neck tissues. The neck area will bulge and feel like crinkling paper to the touch (subcutaneous emphysema). This outcome —in reality, a safety mechanism—will be resolved and thereafter need not be considered a danger. Variant Diagnosis Wheezing may also result from foreign objects or tumors in the bronchial tubes; infections in the tubes, called in­fectious bronchitis; chemical irritants entering the tubes, such as smoke, lyes, noxious gases; or fluid entering the tubes. Fluid may enter the lungs when a person is drowning, or it may originate internally because of damage to the blood vessels of the lungs. Prominent causes are congestive heart failure or pulmonary edema due to a failing heart, long-diseased lung tissue, and drugs such as heroin.

Infants and young children may suffer from a red, flat, scaly rash. Itching is intense and can lead to what is known as "weeping" lesions, caused by the oozing of serum from underlying small blood vessels. Typical places for this to happen are the cheeks, the creases behind the ears, and at the bends of the arms and legs. Commonly called eczema or atopic (allergic) dermatitis, the rash can spread enough to become disabling. During the healing stages, the affected skin thickens and becomes dry and cracked; some bleed­ing may also occur. A local infection that takes the form of skin boils is serious and should be considered a threat. Hives Raised bumps, ranging in size from that of small peas to siz­able portions of the body, may appear anywhere on the body. Each lesion may last only a few hours, but new ones can appear at frequent intervals. The itching may become so intense that it is difficult to perform a task or sleep soundly.

Allergic conjunctivitis can induce a painful, burning condition known as pinkeye. Bright light often adds to the discomfort. Allergic rhinitis, especially in children, may block the Eustachian tubes, which extend from the throat to the middle of the ears. This part of the ear is a closed box devoid of air except for a tiny exit tube that adjusts the ear to pressure changes. When a Eustachian tube is blocked, air is trapped and exerts pressure, resulting in a sharp pain deep within the ears. Known as aerotitis, the condition is some­times caused by sudden changes of air or water pressure, for example, when one goes up a mountain or dives underwater. Allergic rhinitis is also associated with serous otitis media, the leakage of fluid into the middle ear. It causes an aching pain that can temporarily diminish hearing. If untreated, the infection can cause fever and increased pain, and lead ultimately to rupture of the eardrum. In the nasal passages are found outlets from the sinuses —air spaces in the bony structure of the skull. The sinuses near the nose, under the cheeks, and above the eyes (sinuses known, respectively, as ethmoid, maxillary, and frontal) can become obstructed. Buildup of air or fluid leads to greater pressure, which produces pain ranging from a dull ache to a sharp, steady pain around the areas affected. This pain is a symptom of sinusitis. An asthma attack itself can be painful. Additional movement of the chest wall muscles is felt either as a heavy weight on the chest or as tightness. If the complications of pneumothorax, rib fracture, or pneumonia occur, the pain becomes more pronounced, resembling breathing in pleurisy. Although none of these illnesses is life-threatening, any one of them can become troublesome enough to interfere with one’s normal life. They should not, however, cause undue fear or send one to a hospital emergency room. Prompt attention and appropriate medica­tion are a better response.

Blockage of the nasal passages may result from congested nasal tissues caused by hay fever or allergic rhinitis. Other symptoms may be sneezing and watery blood-flecked nasal discharge from the nose or in the back of the throat or both. Throat tickle may provoke cough, and mild asthma may occur. These symptoms will not lead to total impairment of breathing, since breathing through the mouth can substitute for nasal obstruction. Nasal blockage may also result from polyps—nonmalignant growths of sinus and nasal tissue filled with fluid. If the blockage persists unabated for several days, both loss of smell and nasal and sinus infections may result. Variant Diagnosis Not all nasal symptoms are those of allergies. Simple colds or virus infections may simulate allergic disease. These can be distinguished by the presence of fever, general aching, and yellow or greenish nasal discharge. Usually an infection lasts about two weeks, whereas an allergic condition comes and goes over a longer period of time. Persistent nasal obstruction on one side only should make one suspect the presence of a foreign object, or perhaps even a tumor. Asthma that occurs after strenuous exercise is called exercise induced asthma. Such an attack is usually mild and will disappear after rest. If a person has been relatively free of asthma until exposure to animals, cut grass, or a virus, and if the exposure is brief, the attack should subside with proper treatment. It may even subside spon­taneously.

Anaphylaxis is a sudden condition resembling shock that follows within minutes an allergic reaction to a foregn sub stance. It is potentially the most immediately life-threatening allergy emergency, ff the allergen is ingested, as is the case with food or medication, the first symptom may be numbness or tingling in the mouth. This sensation may occur even before the food is completely chewed and swallowed, or it may begin within fifteen minutes after swallowing. The tongue swells, and the throat, or windpipe, feels constricted (from the ensuing edema, or swelling, of the soft tissues). In more severe reactions, the skin, cardiovascular, pulmonary, and gastrointestinal systems can, in rapid sequence, be affected. Hives, rapid heartbeat, lightheadedness, wheezing, nausea, and vomiting can be expected. If the allergen is injected, either by the stinger of an insect or by a physician’s needle, a red swelling at the site is likely to be the first sign. Then, except for a numbness and tingling in the mouth, symptoms similar to those when allergen is ingested may occur. The original site of contact with the allergen is thus involved initially, only to be followed rapidly by general symptoms. Fortunately, spontaneous recovery is the rule; a person recovers within thirty minutes to several hours, and the recovery is nearly always complete. In rare cases, the patient may faint from abnormally low blood pressure, experience seizures, or suffer cardiac damage. Fatal anaphylaxis is rare. A Canadian study has uncovered seven such deaths per year in a population of 6 million. Although penicillin causes some reaction in about 10 percent of the people injected, the death rate is believed to be 1 in 7.5 million injections. Stinging insects inflict large, local (or nonfatal) anaphylactic reactions in slightly less than 1 percent of people stung. The death rate is about 1 per 3.5 million persons per year. In studies called urograms, radiologists and urologists inject radiocontrast dyes to better visualize the kid­neys; it has been estimated that one death has occurred for every 116,000 such examinations. Reaction to an injected dye is called an anaphylactoid reaction. This type of reaction is similar to that of anaphylaxis, although no immunological basis has been discovered. X-ray dyes can release histamine and other chemical agents from cells in the body. For reasons that are poorly understood, in some people these drugs have an exaggerated capacity to act. Why some people have these reactions and others do not has been attributed to a combination of the degree and type of exposure to the provoking agent, and to the immune system. Some individuals have inherited hyper-responding immune systems that produce more immunoglobulin E, as well as other antibodies. Repeated contact with small amounts of the allergen may have produced greater sensi­tization. Injections are more likely to cause general reactions than oral or skin contact. Death is more likely in people over forty or in those with chronic,, severe health problems. Variant Diagnosis Sometimes a person reacts to an injection by fainting. Before doing so, the individual becomes pale, light­headed, and possibly nauseous. Although the person may not suffer from hives or any respiratory difficulty, the pulse is apt to be slow. The individual revives after lying down. The cause is a nervous reaction (in medical terms, a vasovagal reaction) transmitted via the vagus nerve to the heart and blood vessels.

This type of reaction resembles eczema, except that the inflamed skin has sharper borders, does not commonly affect the crease areas, nor does it last as long. Blisters are more likely. Removal and avoidance of the chemical responsible for the blisters will, in most cases, provide relief within two weeks. Hay Fever Itching within the nasal passages, a prominent symptom of hay fever, causes nose-rubbing and facial contortions as a person attempts to relieve the misery. The inner corners of the eyes, and even their entire surface, may itch, resulting in tears. Also, itching of the roof of the mouth can be extremely annoying.