Allergies

The term allergy applies to an abnormal reaction by your immune system to a substance that is usually not harmful. Allergies come in a variety of forms and vary in severity from mildly bothersome to life-threatening. An estimated one-fifth of the Western Hemisphere's population suffers from allergies. No one knows why some people develop them, but heredity seems to play a role in their development. Although allergies may flare up and subside throughout your life, people rarely acquire new ones past the age of 40. 

The immune system protects the body from foreign substances -- known as antigens -- by producing antibodies and other chemicals to fight against them. Usually the immune system ignores harmless substances, such as food, and fights only dangerous ones, such as bacteria. A person develops an allergic reaction when the immune system cannot tell the good from the bad and releases a type of chemical called histamine to attack the harmless substance as if it were a threat. Histamine produces many of the symptoms associated with allergies. Substances that may trigger allergic reactions, known as allergens, range from pollen to pet dander to penicillin. 

Most allergic reactions are not serious, but some, such as anaphylaxis, can result in an inability to breathe or a severe drop in blood pressure and can be fatal. Only a few allergies can be cured outright, but a variety of conventional and alternative treatments are available to relieve the symptoms. If your allergy is severe, it is vital that you visit a conventional medical doctor and get immediate treatment on an emergency basis. 


Symptoms :
Sneezing, wheezing, nasal congestion and coughing may indicate asthma, or drug or respiratory allergies.
Itchy eyes, mouth and throat are frequently symptoms of respiratory allergies.
Stomachache, frequent indigestion and heartburn are signs of food sensitivities.
Irritated, itchy, reddening or swelling skin is associated with drug, food and insect sting allergies.
Stiffness, pain and swelling of joints may indicate food or drug allergies

Causes :
Allergies come in many distinct forms and are typically grouped in general categories according to the types of substances that cause them or the parts of the body they affect. 
Skin allergies: Contact dermatitis is caused by direct, topical exposure to a specific allergen; atopic dermatitis has no known cause, but it is usually hereditary. Hives, or urticaria, is an eruption of itchy, swollen, reddened welts that can last for minutes or days. Angioedema is characterized by a deeper swelling around the eyes and lips, and sometimes of the hands and feet as well. Both hives and angioedema stem from the body's adverse reaction to certain foods, pollen, animal dander, drugs, insect stings, cold, heat, light or even emotional stress. 

Respiratory allergies: Some 20 million Americans suffer from hay fever (allergic rhinitis). Typical symptoms include itchy eyes, nose and roof of mouth or throat, along with nasal congestion, coughing and sneezing. If you (or members of your family) have other allergies such as dermatitis or asthma, you are more likely to have hay fever. The terms allergic rhinitis and hay fever apply specifically to reactions caused by the pollens of ragweed, grasses and other plants whose pollen is spread by the wind. But the same symptoms can be produced by other airborne substances that you inhale. These can include molds, dust and animal dander. If, for example, you are allergic to cat dander (dead skin scales and saliva), being near a cat will make you sneeze, wheeze and sniffle. Mold allergies are caused by airborne spores. Outdoor molds -- alternaria and hormodendrum -- thrive in warm seasons or climates, while indoor molds -- penicillium, aspergillus, mucor and rhizopus -- grow year round in damp locations (basements and bathrooms, for example). Dust causes allergies because it harbors offenders such as pollen, mold spores and microscopic dust mites; it may also contain irritating fibers from fabrics, upholstery and carpets. 

Asthma: Asthma has various causes, but the chief ones are environmental exposures and allergies to pollen, mold spores, animal dander and dust mites. 

Food allergies: An estimated 70 percent of people with food allergies are under 30; most are children under the age of six. It is sometimes difficult to pinpoint the specific allergens responsible for a food allergy, because reactions are often delayed or may be caused by food additives or even by eating habits. However, approximately 90 percent of food allergies are caused by proteins in cow's milk, egg whites, peanuts, wheat or soybeans. Other common food allergens include berries, shellfish, corn, beans, yellow food dye No. 5 and gum arabic (an additive in processed foods). The classic symptoms of food allergies include stomach cramps, diarrhea and nausea. In more severe cases, there may be vomiting, swelling of the face and tongue, and respiratory congestion, as well as dizziness, sweating and faintness. 


Drug allergies: The most common drug allergy is to drugs in the penicillin family. Other common drug allergens include sulfas, barbiturates, anticonvulsants, insulin, local anesthetics and dyes injected into blood vessels for X-rays. Almost one million Americans have reactions to aspirin; these responses are not true allergies but rather "sensitivities." 

Insect sting allergies: Some studies speculate that people who have other allergies (food, drug or respiratory) may be more susceptible to insect sting allergies, which affect about 15 percent of the population. Venom in stings of bees, wasps, hornets, yellow jackets and fire ants is a common allergen (see Insect and Spider Bites). 

Treatment :
The most certain treatment for allergies is to avoid the substances that trigger them, but this can be difficult. The basic medications for allergies are antihistamines, which counteract the histamine chemicals that cause the allergic reactions. Prescription corticosteroid drugs may also be used for severe symptoms. In emergency situations -- when anaphylactic shock occurs -- injections of epinephrine are used to dilate bronchial passages. Immunotherapy, or allergy desensitization shots, may cure some allergies by introducing small amounts of the offending allergens in order to help the body learn to deal with them. 

Respiratory allergies: hay fever is generally treated with over-the-counter antihistamines, but your doctor may prescribe other, more powerful drugs -- such as cromolyn -- if your symptoms are severe. The same treatments apply to other respiratory allergies, but if your symptoms are severe, your physician may prescribe corticosteroids, in nasal spray or oral form. Immunotherapy has a high success rate, curing 70 percent to 80 percent of people treated for respiratory allergies. 

Food allergies (treatment): The best treatment for food allergies is avoidance. If your reactions to certain foods are irritating but not life-endangering, your doctor may prescribe antihistamines or topical creams to help relieve symptoms. 

Drug allergies (treatment): The only effective treatment for drug allergies is avoidance. Skin rashes associated with drug allergies are generally treated with antihistamines; occasionally they are treated with oral or topical corticosteroids. 

Insect sting allergies: Avoidance is the best treatment, but immunotherapy may cure insect sting allergies. If you are extremely allergic and likely to go into anaphylactic shock (see Anaphylaxis), your doctor will prescribe an emergency kit, which you must carry with you at all times. This kit contains a preloaded injection of ephinephrine, a fast-acting drug that counters anaphylactic shock. Your doctor can show you how to use this properly. 

Prevention :
Respiratory allergies: Install a high-efficiency air cleaner to help remove pollen and mold spores, and use an air conditioner in your home and car during warm seasons to keep pollen out; regularly clean damp areas with bleach to kill molds. Consider hiring a special cleaning service to rid furniture and upholstery of dust mites. Isolate your pets and keep them outside as much as possible. Regular baths for your pet will help reduce dander. 

Food allergies: 
Instead of dairy products, try tofu-based foods. Always check food labels for additives that are known allergens, such as yellow food dye No. 5 and gum arabic. When eliminating foods from your diet, be sure to find alternate sources of nutrients. For example, if you cannot eat dairy foods, choose other foods high in calcium or take calcium tablets. 

CONSULT YOUR DOCTOR : 
-If you have violent stomach cramps, vomiting, bloating or diarrhea; this could point to a serious food or other allergic reaction or food poisoning. 
-If breathing becomes extremely difficult or painful; you may be experiencing an asthma episode, another serious allergic reaction or a heart attack. Get emergency medical treatment. 
-If you suddenly develop skin welts, accompanied by intense flushing and itching; your heart may also be beating rapidly. These symptoms may indicate the onset of anaphylactic shock, an extremely serious allergic reaction. Get emergency medical treatment.



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