What are Allergies?

Allergies reflect an overreaction of the immune system to substances that usually cause no reaction in most individuals. These substances can trigger sneezing, wheezing, coughing and itching. Allergies are not only bothersome but many have been linked to a variety of serious chronic respiratory illnesses (such as sinusitis and asthma). Additionally, allergic reactions can be severe and even fatal. However, with proper management and patient education, allergic diseases can be controlled, and people with allergies can lead normal and productive lives.

Important Causes of Allergy

The substances that cause allergic disease in susceptible people are known as allergens. They enter our bodies in a variety of ways:

• Inhaled into the nose and the lungs. Examples are airborne pollens of certain trees, grasses and weeds; house dust that include dust mite particles, mold spores, and cat and dog dander.
• Ingested by mouth. Frequent culprits include shrimp, peanuts and other nuts.
• Injected, such as reactions to penicillin, several other injectable drugs, and stinging insect venom.
• Absorbed through the skin: poison ivy, sumac and oak.
   

What Makes Some Pollen Cause Allergies and Not Others?

Plant pollens that are carried by the wind cause most allergies of the nose, eyes and lungs. These plants (including certain weeds, trees and grasses) are natural pollutants produced at various times of the year when their small, inconspicuous flowers discharge literally billions of pollen particles.

Because the particles can be carried significant distances, it is important for you not only to understand local environmental conditions, but also conditions over the broader area
of the state or region in which you live. Unlike the wind-pollinated plants, conspicuous wild flowers or flowers used in most residential gardens are pollinated by bees, wasps, and other insects and therefore are not widely capable of producing allergic disease.

What is the Role of Heredity in Allergy?

Like baldness, height and eye color, the capacity to become allergic is an inherited characteristic. Yet, although you may be born with the genetic capability to become allergic, you are not automatically allergic to specific allergens. Several factors must be present for allergic sensitivity to be developed:

• The specific genes acquired from parents.

• Exposure to the allergen to which you have a genetically programmed response.

• Sufficient degree and length of exposure.

A baby born with the tendency to become allergic to cow's milk, for example, may show allergic symptoms several months after birth. A genetic capability to become allergic to cat dander may take three to four years of cat exposure before the person shows symptoms.

On the other hand, poison ivy allergy (contact dermatitis) is an example of an allergy in which hereditary background does not play a part. The person with poison ivy allergy first has to be exposed to the oil from the plant. This usually occurs during youth, when a rash does not always appear. Even a first exposure can sensitize or cause the person to become allergic and when subsequent exposure takes place, a contact dermatitis rash appears and can be quite severe. Many plants are capable of producing this type of rash. Substances other than plants, such as dyes, metals, and chemicals in deodorants and cosmetics, can also cause a similar dermatitis.

Many people wonder whether or not they will outgrow their allergies. Although allergic asthma may spontaneously improve, particularly during adolescence, it may also worsen or recur later in life. It is no longer thought that people outgrow these diseases. The diseases sometimes can become dormant and you may be free of symptoms. Still, allergic disease can return or even have its initial onset later in life.

Diagnosing Allergy

If you think you may be allergic to something and do not know what it is, you should start to keep a record of your symptoms. The following information may be useful to
your doctor:

• Do symptoms occur when you are in the house as well as outside (or vice versa)?

• Do you suffer more at night time or during the day?

• Do you wake up with symptoms in the morning?

• Do you only get symptoms at certain times of the year?

• Does exposure to animals bring on your symptoms?

• Do you think that any food or drink brings on your symptoms? 

Avoidance and environmental changes

For most allergies and asthma, the best treatment is to avoid the allergen. This is easier for foods and more difficult for inhalant allergens.

For food allergies, a number of books have been written with recipes and advice. Altering the diet to exclude certain foods can be easy if the food is relatively uncommon or is easy to spot. For example, shellfish, melons, citrus and bell peppers are usually easy to spot and avoid. Foods like eggs, wheat, corn, peanuts and milk are harder to spot as they may be hidden ingredients in a number of foods. Many recipes are available that are easy, tasty, and avoid the allergen.

For seasonal allergens (pollens), try to stay indoors as much as possible and avoid going out during peak pollen times (usually early mornings.) Filter masks are available that
	prevent breathing in allergens. For household allergens (mold, dust, dander), the best approach is minimizing places for the stuff to gather. Vacuum often; once a day is recommended by some. Make sure allergy-prone people (especially asthma sufferers) are out of the house before any painting, waxing, or other fume- producing activity occurs. Air filtering systems are available for individual rooms and as whole-house systems. Furry pets are a big source of dander and should be kept out of bedrooms.
Ragweed Pollen magnified 600X

Allergy shots, also known as immunotherapy, decrease your sensitivity to allergens by introducing you slowly to increasingly larger doses of the substance to which you're allergic.

The vaccines are selected to match your allergies. For example, if you're allergic to
insect stings, you get a vaccine derived from insect venom. Other vaccines may be derived from pollens, mold spores, animal dander or dust mites.

Allergy shots have improved in a number of ways over the years, says Dr. Hendrick Nolte, associate professor of internal medicine and pulmonology at Bispebjerg University Hospital in Copenhagen, Denmark. The vaccines themselves are better standardized, which improves their quality and effectiveness. Also, there are now guidelines for prescribing and administering allergy shots, experts say.

Nolte says patients first receive between six and eight weekly shots, and then receive one injection a month for about three years. He says allergy shots are effective for about 80 percent of people with hay fever and 50 percent to 60 percent of people with asthma.

One drawback to allergy shots is the ordeal for people who hate needles. Scientists are currently trying to create nasal sprays and pills that can deliver vaccines in a less painful way but there is much more research and development needed.