Allergy Overview

What are allergies?

Allergies are problems of the immune system. Most allergic reactions happen when the immune system reacts to a “false alarm.” Normally, the human body defends itself against harmful things, such as viruses or bacteria. But sometimes the defenses violently attack mostly mild things, such as dust, mold, or pollen.

The immune system makes large amounts of the antibodies called immunoglobin E (IgE). This is a complex chemical weapon that attacks and kills the “enemy.” Each IgE antibody exactly targets a certain allergen or thing that causes the allergy. In this way, inflammatory chemicals, such as histamines, cytokines, and leukotrienes, are made and given off. This causes an allergic person to feel some bad or even life-threatening symptoms.

What causes allergies?

Allergens are substances that can be breathed, swallowed, or come in contact with the skin. Common allergic reactions, such as hay fever, certain types of asthma, and hives, are linked to an antibody made by the body. This antibody is called immunoglobulin E or IgE. You can be allergic to one type of pollen, but not another. When you are exposed to an allergen, your body starts making a large amount of matching IgE antibodies. When exposed to the same allergen at a later point, you may have a reaction. Symptoms of an allergic reaction will differ based on the type and amount of allergen you have come in contact with. It also depends on how the body’s immune system reacts to that allergen.

The most common allergens are:

  • Pollen
  • Mold
  • Household dust, dust mites and their waste
  • Animal dander, urine, or oil from skin
  • Chemicals used for manufacturing
  • Food
  • Medicine
  • Feathers
  • Bug stings
  • Cockroaches and their waste
  • Latex

Who is at risk for allergies?

Allergies can affect anyone, no matter what age, gender, race, or socioeconomic status. Often, allergies are more common in children. But a first-time event can happen at any age, or come back after many years of remission.

There’s a tendency for allergies to happen in families. Although the exact family links that cause it aren’t yet understood. In sensitive people, things such as hormones, stress, smoke, perfume, or other environmental irritants, may also play a role. Often, the symptoms of allergies grow slowly over a period of time.

You may become used to constant symptoms, such as sneezing, nasal congestion, or wheezing. You may not think that the symptoms are unusual. But, these symptoms can often be stopped or controlled with the help of a doctor who specializes in treating allergies. And you can have a better quality of life.

What are the symptoms of allergies?

An allergic reaction can happen anywhere in the body. This includes the skin, eyes, lining of the stomach, nose, sinuses, throat, and lungs. These are the places where immune system cells are found to fight off germs that are in breathed in, swallowed, or come in contact with the skin. Allergic reactions can cause:

  • Stuffy nose, sneezing, itching, or runny nose, and itching in ears or roof of mouth
  • Red, itchy, watery eyes
  • Red, itchy, dry skin
  • Hives or itchy welts
  • Itchy rash
  • Asthma symptoms, such as shortness of breath, coughing, wheezing

How are allergies diagnosed?

To diagnose an allergy, your healthcare provider will give you an exam and review your health history. He or she may also do these tests.

  • Skin test. The skin test is a way of measuring the level of IgE antibodies to certain allergens. Using diluted solutions of certain allergens, the healthcare provider either gives you a shot with the solutions or puts them directly on your skin by making a scratch or small puncture. A small red area on the skin means that you have had a reaction.
  • Blood test. The blood test is used to measure the level of IgE antibodies to specific allergens. One common blood test is called radioallergosorbent test or RAST. Newer tests have been developed that may be better than RAST. Ask your doctor about all available allergy blood  tests.