All About Allergies 
Wednesday, 02 November 2005 
What do dust, cats, peanuts, and cockroaches have in common? Believe it or not, they all can cause allergies. Allergies are one of the major causes of illness in the United States. In fact, up to 50 million Americans have some type of allergy.

What are allergies?

An allergy is a reaction of the immune system to a substance that is harmless to most people. If you have an allergy, your immune system treats the substance (or allergen) as an invader. As a result, you can have symptoms that can range from annoying to possibly harmful.

The immune system of an allergic person attempts to protect the body by producing antibodies. The antibodies then cause mast cells to release chemicals into the bloodstream to defend against the allergen. One of the chemicals produced is histamine.

The release of these chemicals causes allergic reactions which can affect your eyes, nose, throat, lungs and skin as your body attempts to get rid of the allergen. Each time you are exposed to the same allergen your body will have the same allergic reaction.

Who gets allergies?

The tendency to develop allergies is often passed down through your genes. This doesn’t mean that if you have an allergy every member of your family will have allergies too. And a person usually doesn’t inherit a particular allergy, just the likelihood of having allergies. But a few children have allergies even if no family member is allergic. These children will likely be allergic to more than one substance.

Airborne Allergens

Some of the most common things people are allergic to are airborne. These allergens are:

  • Dust Mites – This is one of the most common allergens. Dust Mites are microscopic insects that live all around us and are present year-round in most parts of the United States.

  • Pollen – This is another major cause of allergies. It is mostly referred to as hay fever. Trees, weeds, and grasses release pollen into the air, causing people with these allergies to develop symptoms. Pollen allergens are seasonal, and pollen counts measure how much pollen is in the air so people can determine how bad their symptoms might be on any given day.

  • Molds – Molds, a common allergen, are fungi that develop indoors and out in warm, moist environments. They can be found outdoors in areas with poor drainage and indoors in dark, damp, poorly ventilated places. Mold can affect people with allergies year round.

  • Pets – Allergens from pets comes from their fur dander. The particles can become airborne and work their way into fabrics in the home.

  • Cockroaches – They are a major allergen in inner-city homes. They may be a major cause of asthma in inner-city children.

Airborne allergy symptoms can include sneezing, itchy eyes, nose and throat, nasal congestion, and coughing. If a person has these symptoms, as well as shortness of breath and wheezing, the allergy may have progressed to become asthma.

Food Allergens

  • Cow’s Milk – Infants, children and adults can have an abnormal immune system reaction to the proteins found in cow’s milk.

  • Eggs – This is one of the most common food allergies in infants and young children. It is hard to diagnose because eggs are used in many foods (in some cases they’re “hidden” ingredients) that children eat. The allergy usually starts when a child is very young but most outgrow it by the age of 5.

  • Fish and shellfish – The proteins in fish can cause several types of allergic reactions, including diarrhea and vomiting. Other reactions are itching and dryness of the skin.

  • Peanuts and tree nuts – Peanuts are one of the most severe food allergens, often causing life-threatening reactions. Half of the people who are allergic to peanuts are allergic to tree nuts, such as almonds, walnuts, pecans, sunflower and sesame seeds, and cashews.

Food allergy symptoms can include itchy mouth and throat, hives (raised, red, itchy bumps), rash, runny, itchy nose, and abdominal cramps with nausea and vomiting or diarrhea.

Other Allergens

  • Insect Stings – Being stung by an insect usually means swelling, redness, and itching at the site of the bite. But for those with insect venom allergy, an insect bite can cause severe symptoms.

  • Medicines - Medications that are used to treat infections (antibiotics) are the most common types of medicine that cause allergic reactions. Other medications can also cause allergic reactions, including over-the- counter medications.

  • Chemicals – Some household detergents, cleaners and pesticides can cause people to break out in an itchy rash. Cosmetics can cause an allergic reaction in some people. The chemicals in these products are usually what cause the reaction.

What are the signs and symptoms of allergies?

The type and severity of allergy symptoms vary. Symptoms can range from minor to major seasonal problems (pollens, molds) to year-round problems (dust-mites, food).

Airborne Allergy Symptoms

This type of allergen can cause allergic rhinitis. It reaches its peak in the early 20s and can often disappear between the ages of 40 and 60. The symptoms can include:

  • Sneezing

  • Itchy nose and/or throat

  • Nasal congestion

  • Coughing

Symptoms often include itchy, watery, and/or red eyes (allergic conjunctivitis). If a person has allergic rhinitis and allergic conjunctivitis as well as wheezing and shortness of breath, the allergy may have progressed to become asthma.

Food Allergy Symptoms

Symptoms of food allergies can include:

  • Itchy mouth and throat

  • Hives

  • Rash

  • Runny, itchy nose

  • Abdominal cramps with vomiting or diarrhea

Insect Venom Allergy Symptoms

Being stung by an insect that one is allergic to can cause:

  • Throat Swelling

  • Hives

  • Breathing Difficulty

  • Nausea and/or diarrhea

Extreme Allergic Reactions

If one has an extreme sensitivity to an allergen, they can experience anaphylaxis, or anaphylactic shock. This is a sudden, severe reaction that involves various systems in the body (skin, respiratory tract, cardiovascular system). Severe symptoms require immediate medical attention. They can include:

  • Difficulty Breathing

  • Swelling of the face, throat, lips and tongue

  • Rapid drop in blood pressure

  • Dizziness and/or lightheadedness

  • Unconsciousness

  • Hives

  • Tightness of the throat

  • Nausea and/or vomiting

  • Abdominal pain

  • Diarrhea

Anaphylaxis can happen almost immediately after being exposed to the allergen or up to two hours after exposure if the allergen is food. Various areas of the body can be affected.

How are allergies diagnosed?

Some allergies are easy to diagnose because the pattern of symptoms after exposure to certain allergens is easy to follow. Other allergies are less obvious because the symptoms are similar to other conditions.

Skin tests are performed by allergists to diagnose most environmental and food allergens. They can be done in two ways:

  • A drop of the allergen in purified liquid form is dropped on the skin and the area is pinched with a small pricking device.

  • A small amount of allergen is injected under the skin. The area is checked after 15 minutes for a reaction. If a lump surrounded by a reddish area appears, the test is positive.

If symptoms are severe a blood test may be used to diagnose the allergy to avoid exposure to the allergen.

Even if these tests show positive for an allergen, symptoms must occur to have a definitive diagnosis.

How are allergies treated?

It is possible to relieve allergy symptoms, but there is no real cure for allergies. The best way to control them is to reduce or eliminate exposure to the allergens. If this isn’t possible, medications that include antihistamines and inhaled or nasal spray steroids can be prescribed. You can buy antihistamine medications over the counter. In some cases, an allergist may recommend allergy shots (immunotherapy) to help desensitize you.

What does injectable epinephrine do?

If you are extremely sensitive to any foods or insect venom and symptoms are severe, your doctor may recommend that you carry injectable epinephrine to counteract any allergic reactions. This is in a container that looks like a pen. The device administers epinephrine through one injection in the thigh. An injectable epinephrine prescription usually includes two auto-injections and a “trainer” that contains no needle for you to use to practice using the device.

Anyone who has had to take injectable epinephrine should go immediately to an emergency medical facility where additional treatment can be given if needed. A second wave of symptoms can occur several hours following the initial attack.


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