An allergy or allergic reaction is the body’s response to an allergen, a foreign substance that enters or comes into contact with the body. Normally, the body’s immune system produces antibodies to fight disease. In an allergy, the body overreacts to the allergen, which may be something rather harmless. Allergic reactions may be caused by the production of an antibody called immunoglobulin E (IgE).
The experience of an allergy depends on the body system or tissues that are affected, the severity of the reaction, and whether the substance that triggers the allergy can be eliminated from the patient’s diet or living situation. Some allergies affect only a small part of the body, like a skin rash on the wrist caused by touching certain metals in inexpensive costume
jewelry. Other allergies may affect several major body systems, as in the severe reactions that some people have to bee stings or certain medications. These reactions are especially related to IgE antibodies. Some allergies are caused by substances that can be avoided, such as certain foods, while others may be triggered by exposure to plant or tree pollens that are hard to avoid when the plants are in season.
In general, when a person who has allergies comes into contact with an allergen, the person’s immune system produces IgE antibodies that are specific to that allergen. The IgE antibodies trigger the release of a chemical called histamine. The histamine, in turn, causes the tissue swelling, difficult breathing, skin rash, watery eyes, runny nose, and other symptoms of an allergy.
The release of the histamine often attracts other cells from the immune system to the
affected part of the body, increasing the inflammation, tissue swelling, and production of large amounts of mucus— otherwise making the patient’s symptoms worse.
Researchers do not yet fully understand why some substances produce allergies in susceptible people and others do not, nor why some people do get allergies and others do not.
The most common types of allergies among people in North America are:
• Hay fever.
• Allergic conjunctivitis (inflammation of the tissue that lines the eyelid).
• Eczema. Eczema is sometimes called atopic dermatitis because it is a hypersensitivity reaction that affects a part of the body that is not in direct contact with the allergen. Hay fever and asthma are also considered atopic allergies.
• Severe reactions to insect stings, certain foods, and certain medications. This type of severe allergic reaction is called anaphylaxis.
• Food allergies. Most cases of food allergies are caused by just eight foods: eggs, fish, milk, peanuts, shellfish, soy, tree nuts (walnuts, hazelnuts, almonds, etc.), and wheat.
• Contact dermatitis. In contrast to eczema, contact dermatitis is an inflammation of the skin caused by direct contact with an allergen or irritating substance, such as poison ivy, certain dyes, or certain metals, especially nickel.
Allergies are very common health problems in all age groups in the general population. About 50 million people in the United States suffer from some type of allergy, many of them from more than one. For example, about 20 percent of people who get hay fever eventually develop asthma, and some develop eczema as well.
Some statistics for specific allergies are as follows:
• Hay fever: 20 percent of the population in developed countries.
• Asthma: 20 million people in the United States.
• Anaphylaxis: Affects between 1 and 3 percent of the population in developed countries.
• Eczema: about 15 million people in the United States.
• Hives: 20 percent of the population in developed countries.
• Food allergies: about 8 percent of school-age children.
There are two major types of risk factors for allergies: genetics and the environment. Allergies run in families, with allergic parents likely to have allergic children. Children are not necessarily allergic to the same substances as their parents. For example, the parent could be allergic to ragweed pollen while the child is allergic to peanuts. In general, allergies are more severe in children than adults. Several studies have shown that IgE levels are highest in young children and fall rapidly in people between the ages of ten and thirty years. Among children, boys are almost twice as likely as girls to develop allergies, but the sex difference disappears among adults. Environmental factors are thought to explain why the rate of allergic diseases has increased around the world since the 1980s. These factors include dietary changes, a rise in air pollution, an increase in the levels of other allergens in the environment, and the fact that children are exposed to fewer infectious diseases than they were in the past. Some doctors think that exposure to and recovery from these diseases made children less susceptible to allergies.
Nursing Care Plan Assessment | Causes and Symptoms
An allergic reaction is caused by the individual person’s immune response to an allergen. The symptoms of allergies may appear in one or more body systems:
• Skin: Redness, itching, bumps or wheals, crusting, weeping patches, blisters.
• Respiratory tract:Wheezing, sneezing, coughing, difficulty breathing, stuffy or runny nose.
• Digestive tract: Nausea, vomiting, diarrhea, stomach cramps.
• Eyes: Itching, watering, bloodshot or puffy appearance.
• Other: Headache, dizziness, ringing in the ears.
Nursing Care Plan Diagnosis
In some cases the allergen is easy to identify because the person has a pattern of symptoms that appears after exposure to the food, substance, or other trigger. In other cases the person may have to consult a specialist to identify the allergens that are causing the symptoms. The usual method of testing involves either a skin test, in which a small quantity of a possible allergen is injected under the skin, or a blood test known as the radioallergosorbent test (RAST). The RAST test is usually done in place of the skin test when the patient has had severe reactions to the allergen.
Nursing Care Plan Intervention and Treatment
Anaphylaxis is a medical emergency that requires immediate treatment by a medical professional or emergency rescue team. There is no cure for allergies. However, most can usually be treated with antihistamines and other medications that the doctor may recommend, depending on which part of the body is affected. The most important step in treatment, however, is avoiding the allergen if at all possible. Minimizing exposure to the allergen may involve installing air filters in the home, eliminating certain foods from the diet, cleaning the house frequently, moving to a part of the country with fewer pollen-producing plants, or other measures that the doctor may recommend.
Another approach to treating hay fever, asthma, allergic conjunctivitis, and some other allergies is desensitization, which is also called immunotherapy. In desensitization, patients are given a series of injections of their specific allergen under the skin, with the concentration of allergen in the shots being gradually increased. It takes an average of eight to twelve months for the patient to see results, however, and the injections must be taken for at least three years and sometimes closer to five years. Although several alternative therapies—including herbal medicine, traditional Chinese medicine, and naturopathy—have been tried as treatments for allergies, a long-term study conducted by the Mayo Clinic in 2006 concluded that none of these was effective.
Most allergies are not life-threatening, the exceptions being anaphylaxis and asthma. About 5,500 people die each year in the United States from asthma and another 500 from anaphylaxis. In general, allergies tend to become less severe as people grow older. The major exception is food allergies (especially to peanuts), which can last a lifetime.
There is no way to prevent people from developing allergies because the genetic factors that are involved in allergic reactions have not been fully understood. Desensitization therapy and avoidance of specific allergens are the only effective methods of prevention at present.
Public health experts expect allergies of all types to become more common in the developed countries in the future as a result of lifestyle changes and a larger proportion of the world’s population living in large cities. As of 2008, some researchers were working on a vaccine that would