More than 50 million Americans suffer from allergic diseases. One of the most common forms of allergies is an allergic reaction to something in the air. Health experts estimate that 35 million Americans suffer from upper respiratory tract symptoms that are allergic reactions to airborne allergens (substances that can cause an allergic reaction).
This article discusses airborne allergies. Additional eMedTV articles focus on other types of allergies, such as allergies to latex or certain foods. Click
Food Allergy and
Latex Allergy for more information on these topics.
Allergies occur when the body's immune system reacts to a normally harmless substance -- one that does not bother most people. People who have allergies are often sensitive to more than one substance. Examples of allergens that cause allergic reactions include:
- Pollens
- House dust mites
- Mold spores
- Food
- Latex rubber
- Insect venom
- Medicines.
Understanding the Immune System and an Allergic Reaction
Normally, the immune system functions as the body's defense against invading germs such as bacteria and viruses. In most allergic reactions, however, the immune system is responding to a false alarm. When a person with allergies first comes into contact with an allergen, the immune system treats the allergen as an invader and gets ready to attack.
The immune system does this by generating large amounts of an antibody called immunoglobulin E, or IgE. Each IgE antibody is specific for one particular substance. In the case of pollen allergies, each antibody is specific for one type of pollen. For example, the immune system may produce one type of antibody to react against oak pollen and another against ragweed pollen.
The IgE molecules are special because they are the only type of antibody that attaches tightly to the body's mast cells (a certain type of tissue cell) and to basophils (a type of blood cell). The next time the allergen encounters its specific IgE, it attaches to the antibody like a key fitting into a lock. This action signals the cell connectected to the IgE to release (and in some cases, to produce) powerful chemicals that cause inflammation. Histamine is one of these chemicals. These chemicals act on tissues in various parts of the body, such as the respiratory system, and cause
allergy symptoms.
Asthma research scientists do not know for sure why one person develops allergies and another does not. It is believed that allergies originated millions of years ago as a way for the human body to rid itself of parasites and invading worms. Scientists also believe that some people inherit a tendency to be allergic from one or both parents. Children, for example, are more likely to develop allergies if one or both parents have allergies. However, it is unlikely to inherit a tendency to be allergic to any specific allergen.
Being exposed to allergens at times when the body's defenses are lowered or weakened -- such as after a viral infection or during pregnancy -- also seems to contribute to developing allergies.
Seasonal Versus Perennial Allergies
Allergies can either be seasonal or perennial. Seasonal allergies occur at specific times of the year, while perennial allergies can occur throughout the year.
Of these two types of allergies, perennial allergies tend to be more difficult to treat.
The allergens that most commonly cause seasonal allergies are:
The allergens that most commonly cause perennial allergies are:
The symptoms of allergies are familiar to many. The most common airborne allergy symptoms include:
- Sneezing, often with a runny or clogged nose
- Coughing and postnasal drip
- Itching eyes, nose, and throat
- Watering eyes
- Conjunctivitis (inflammation of the membrane that covers the eye)
- "Allergic shiners" (dark circles under the eyes caused by increased blood flow near the sinuses)
- "Allergic salute" (in a child, persistent upward rubbing of the nose that causes a crease mark on the nose).
Treatment Options for Allergies
Combined with a number of strategies to minimize a person's contact with allergens, allergy treatment medications can make life bearable for even the worst allergy sufferer.
Allergy shots are another form of treatment for allergies.
Allergies Versus Chemical Sensitivity
Some people have allergy-like reactions to the chemicals found in a wide variety of synthetic and natural substances. These substances can include things like:
- Paints
- Carpeting
- Plastics
- Perfumes
- Cigarette smoke
- Plants.
Although a person's symptoms may resemble those of allergies, sensitivity to chemicals does not represent a true allergic reaction involving IgE and the release of histamine or other chemicals. Rather than a reaction to an allergen, the person is experiencing a reaction to a chemical irritant. People with allergies may have a greater sensitivity to chemicals than those without allergies.
Add this article to your Favorites
Email this article
Print