What Are Allergies?

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).

Allergies are the immune system's specific reaction to a normally harmless substance such as pollens, certain foods, or medicines. There are two main types, seasonal and perennial. The seasonal variety occurs at specific times of the year, while the perennial variety can happen year-round. In many cases, successful treatment involves medication, reducing contact with specific allergens, or shots.

 

Definition of an Allergy

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:

 

st george pollen allergies Pollens

st george pollen allergies House dust mites

st george pollen allergies Mold spores

st george pollen allergies Food

st george pollen allergies Latex rubber

st george pollen allergies Insect venom

st george pollen allergies Medicines

 

Understanding the Immune System

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 connected 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.

 

What Causes Allergies?

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 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.

 

Common Allergens

The allergens that most commonly cause seasonal allergies are:

 

st george pollen allergies Tree pollen

st george pollen allergies Grass pollen

st george pollen allergies Weeds

st george pollen allergies Fungi and molds

 

The allergens that most commonly cause perennial allergies are:

 

st george pollen allergies House dust

st george pollen allergies Dust mites

st george pollen allergies Cockroaches

st george pollen allergies Animals

st george pollen allergies Cigarette smoke

st george pollen allergies Fungi or molds.

 

What Are the Symptoms?

The symptoms of allergies are familiar to many. The most common airborne allergy symptoms include:

 

st george pollen allergies Sneezing, often with a runny or clogged nose

st george pollen allergies Coughing and postnasal drip

st george pollen allergies Itching eyes, nose, and throat

st george pollen allergies Watering eyes

st george pollen allergies Conjunctivitis (inflammation of the membrane that covers the eye)

st george pollen allergies "Allergic shiners" (dark circles under the eyes caused by increased blood flow
     near the sinuses)

st george pollen allergies "Allergic salute" (in a child, persistent upward rubbing of the nose that causes
     a crease mark on the nose).

 

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:

 

st george pollen allergies Paints

st george pollen allergies Carpeting

st george pollen allergies Plastics

st george pollen allergies Perfumes

st george pollen allergies Cigarette smoke

st george pollen allergies 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.