An allergy is an abnormally high sensitivity to a specific substance, such as dust, pollens, foods, or drugs. Symptoms of allergies commonly include inflammation, sneezing, itching, and skin rashes.
An allergic reaction occurs when your immune system reacts to a foreign substance from the outside world. These foreign substances, normally small proteins, can come from dust mite feces, pollens, molds, and many other natural and man-made objects. When your immune system mistakes these normally harmless foreign substances as dangerous invaders and sends out antibodies to attack them, then the foreign substances are referred to as "allergens," and you will experience the symptoms of an allergic reaction.
In terms of the actual CAUSE of a specific allergy, there is much debate. Some studies show that cleaner homes, less exposure to common allergens, and less time spent outdoors do not allow for the immune system to properly "train" - identify substances and categorize them as harmless or harmful, and thus, the system is prone to overreact. Other research shows an increasingly strong link between our microbiome (the thousands of species of fungi and bacteria that live on and inside us) and the development of allergic disease.
The most common allergens include dust mites, mold/mold spores, pollen, animal dander, cockroaches, peanuts, milk, eggs, latex, and penicillin. The dust mite is the most common cause of allergies, but food allergies have risen in recent years.
An allergist or immunologist can diagnose your allergies using allergy skin tests, which show if your immune system reacts to specific allergens. Blood tests can also show the present of antibodies, which indicate a sensitivity. Testing alone though is NOT a proper diagnosis of an allergy. Beyond tests, your personal medical history and family medical history are also factored in with your conditions in your environment to get a more complete view of the situation and make a proper diagnosis.
The most common allergic diseases are allergic rhinitis (hay fever), asthma, allergic dermatitis (eczema), contact dermatitis, food allergy, and urticaria (hives). Allergic disease can be classified by the type of allergen (i.e., food allergy) or by the part of the body that is affected. For example, if allergic symptoms appear in your nose, you are said to have allergic rhinitis. If allergic symptoms appear in your lungs, then you have asthma.
Allergies can be treated with medicine that alleviates symptoms or immunotherapy (allergy shots or drops) that desensitize the patient to specific allergens with weekly shots over several years. More recently, testing is ongoing regarding allergy vaccines and other types of immunotherapy that are less invasive. One of the best methods of treating allergies is allergen avoidance. This type of treatment is a treating of you and more a treating of your environment. Avoidance measures act exactly as they sound - allow you to avoid allergens and triggers by eliminating or reducing exposure to them in your home or office. If you're allergic to dust mites, for instance, a highly effective path to wellness would be to eliminate/reduce the dust mites from your home. In this case, it can be done in a variety of ways from the expensive - replacing carpet with smooth or hard flooring to the really inexpensive - using a pillow cover or dusting/vacuuming/cleaning more frequently.
Over 50 million Americans suffer from allergies, and approximately 55 percent of all U.S. citizens test positive to one or more allergens.
There is a genetic factor in the development of allergic disease. If one parent has allergic disease, the estimated risk of a child to develop allergies is 48%; the child's estimated risk grows to 70% if both parents have a history of allergies.
The genetic factor does not explain why the incidence of allergy and asthma is rapidly increasing in the modern world. There are a few theories about why allergic disease is growing. One theory blames our increasing immune system sensitivity on the abundance of synthetic chemicals in our modern world. Another theory, known as the hygiene hypothesis, posits that the human immune system is becoming more reactive to allergens because of modern hygiene and healthcare. Our immune system is designed to fight off viruses, bacteria, parasites, and other microbes; however, with modern hygiene, sanitation, vaccines, antibiotics, and healthcare, our immune system does not have many invaders to fight off, and so its attention and energy is re-directed to normally harmless foreign substances. Yet another theory is a variation of this that actually combines the two former whereby chemicals or changes in our natural environment kill off or alter many of the good microbes in and on our bodies that seem to have a strong connection to the development of allergic disease.
People with seasonal allergic rhinitis (hay fever) only experience symptoms during the time of year when certain allergens are in the air outdoors. When most people talk about allergy season, they're referring to springtime, when plants bloom and pollen counts soar. However, summer is the season for grass and weed pollen allergies, and autumn is the time for ragweed and mold allergies. During the winter months, cedars in the American Southwest and other parts of the country dump large amounts of pollen in the air. Perennial allergies, or year-round allergies, are typically caused by indoor allergies to dust mites, mold, cockroaches, and pet dander.
It normally works the other way around. People often grow into allergies, particularly environmental allergies. Some children outgrow food allergies after long periods of avoiding the allergen, and up to half of young children outgrow their asthma, but many find that the symptoms return later in life.
Allergic reactions can develop at any age, no matter how old you are. If someone's total allergen load reaches its maximum point, then s/he will most likely develop allergies. The peak age of allergy development, however, appears to be in the late teens.
Anaphylaxis is the most severe and potentially fatal end of the allergic reaction spectrum. It's difficult to precisely report how many people die from anaphylaxis because the cause of death may often appear to be a heart attack. Fatal anaphylaxis normally occurs because of extreme allergic reactions to foods such as shellfish, cod, or peanuts, or to the venom of stinging insects like wasps or fire ants. Approximately 100 Americans die annually from anaphylaxis induced by stinging insects. Penicillin is the most common culprit in death from drug allergy. Anaphylactic reactions to penicillin cause approximately 400 deaths a year.
Besides potential death, there are other long-term dangers of allergies. Repeated allergic reactions in certain areas of the body can result in damaged organs. Asthma, for example, can lead to irreversible damage to lung tissue and conditions like emphysema.
The most common foods behind allergic reactions include nuts, peanuts, milk, egg, wheat, and soy bean proteins. Some food preservatives, such as metabisulfate and monosodium glutamate (MSG), can also cause allergic reactions. Metabisulfate is in most wines that need preserving, and although MSG is normally associated with Chinese food, it is present in a high percentage of processed foods and often listed on the label by another name such as glutamic acid, hydrolyzed vegetable protein, or yeast extract.
Allergen avoidance is currently the best treatment for any allergic disease. Avoid the allergen, and you'll avoid the allergic reaction. Diagnosis and education are crucial steps in allergen avoidance. Educated allergy and asthma sufferers fare much better than those who do not understand their disease.