allergies 101

An allergy is present whenever the immune system reacts to a commonly encountered, normally harmless substance, (the allergen) as if it were a threat to the body, and then triggers an immune response for protection.  This reaction is actually abnormal and unnecessary, as the body is not under attack and this reaction does not occur in non-allergic people. 

Allergens may be encountered by touch, inhalation or ingestion.  Allergic people have developed antibodies against the substances which trigger their allergies.  This may be hereditary, and it is not known why some people develop them and others dont.  The antibodies attach to the allergen, triggering a cascade of reactions in the cells of the immune system. An allergy will typically not occur the first time there is contact with the substance.  On repeated exposure, the antibodies are produced, chemicals such as histamines are released, and the symptoms of allergy present themselves.

Allergy symptoms vary depending on the type of contact with the substance, but include sneezing, coughing, wheezing, difficulty breathing, pain in the sinus area, runny nose, skin rashes, swelling and itching of the eyes, ears and mouth, diarrhea, nausea and vomiting.  In rare cases, the allergic reaction can be almost instant and very severe, involving the whole body, particularly the respiratory and circulatory systems.  This is called anaphylactic Shockã?»and can be fatal.  Blood pressure increases and there is swelling in the mouth and throat and difficulty breathing.  People in anaphylactic shock need emergency treatment with epinephrine, and those with severe allergies often carry their own supply as this can be life-saving.  Contact with allergens may trigger asthma attacks in asthmatics.  Prevention of allergies is particularly important for these people, as allergies can dramatically increase the severity of asthma.

These common substances trigger allergies on inhalation:

Pollen from trees and grasses:  Pollen is produced seasonally and causes allergic rhinitis, or hay fever.  Symptoms include sneezing, itchy, watering eyes, nasal congestion and a runny nose.  These can be minimized by reducing exposure to pollen, for example staying indoors during times of high pollen and using an air purifier to remove pollen from the air inside the home. 

Dust mites:  These are microscopic organisms which live in dust.  Symptoms are very much like pollen allergy, but will occur year round.  Preventative measures include removing items which will trap dust, such as carpeting, and using hypoallergenic covers on pillows, bedding and soft furnishings. Aside from this, the most effective way to eliminate dust mites is again, an air purifier to remove them from the air inside the home. 

Pet dander:  Skin flakes shed from pets can remain in the environment for up to 6 months.  Saliva and urine can also cause allergies. Pet hair though, is typically not allergenic.  Pet droppings can harbor allergenic molds.  Pet allergies generally develop over several years, and symptoms may persist for months after the last contact with the pet.  Symptoms include sneezing, nasal congestion and itchy, watering eyes.  Reduction in the amount of contact with the pet will help reduce symptoms, but a high quality air purifier is the most effective way remove dander from the air.

Mold and fungal spores:  These are found in damp areas of the home, such as bathrooms and cellars, or in houseplant soil.  They are also present outside, for example in piles of leaves, and exposure to these may cause seasonal allergies.  Symptoms include coughing and sneezing, congestion and running nose and eyes.  Mold needs moisture to grow, so a good dehumidifier is essential to keeping it from developing, and a high quality air purifier is key to removing mold and fungus from the air.

Substances which can cause allergies on ingestion, include:

Foods and food preservatives: The most common allergenic foods are milk, eggs, seafood, wheat, Soya, nuts and certain fruits.  Swelling around the mouth, asthma, nausea, vomiting, diarrhea and skin rashes may be seen.  Allergic individuals will need to avoid the allergenic food as even very small amounts can cause severe reactions. One of the most common causes of anaphylactic shock is a food allergy.

Medications: Some medications, such as aspirin and penicillin, can cause allergic reactions in susceptible individuals.  Symptoms include swelling of the mouth and throat, skin rashes, congestion, itchy eyes and may be life-threatening.  Allergic individuals need to wear a bracelet to warn medical staff of their allergies should they require emergency medical treatment.

Substances which cause allergies on skin contact, include:

Insect stings:  Insect stings may produce extensive swelling and redness, nausea, mild fever and are the other most common cause of anaphylactic shock in allergic individuals.  Insects which commonly cause allergic reactions, include some bees, fire ants, wasps and hornets.

Latex: latex in gloves, condoms or medical devices can cause allergies.  Symptoms vary from skin rashes and redness in mild cases to coughing, sneezing, breathing difficulties, itching of the skin and nose or even anaphylactic shock.  Sensitive individuals will need to avoid all contact with items containing latex.

Allergies are most commonly diagnosed by skin tests.  The most simple form is the prick test, which  involves placing a small amount of allergen on the skin and then abrading it slightly so the allergen penetrates.  If the test is positive, redness and swelling will be seen after about 15 minutes, indicating that the person has antibodies to the allergen.  Skin testing is the oldest and most reliable form of allergy testing.  However, a person may have a positive test and yet show no symptoms when exposed to the allergen in the environment, so the doctor must interpret the results of the test in light of the symptoms seen. 

If the results of the prick test are inconclusive, for example the tests are negative although allergy symptoms are seen, an intra-dermal skin test may be carried out.  This involves injecting allergen into the uppermost skin layer and is more sensitive.  However, it cannot be used for food allergies and may produce false positive results.  It is necessary to stop taking anti-histamines before skin testing, as these would mask a positive reaction.  This test cannot be done on people with sensitive skin who would react simply to the abrasion.  Skin testing is very safe when performed by a trained doctor, and reactions such as anaphylactic shock are very rare. 

The only other form of allergy testing is radioallergosorbent testing (RAST).  This is a blood test to measure levels of antibodies to specific allergens.  It is particularly useful, as the antibody level will give an indication of how allergic someone is to an allergen, so can be used to test for example, whether a child has outgrown a food allergy.  As the test only involves giving a blood sample, there is no risk of anaphylaxis.  It may be a better test for those with lung and heart conditions who would be at greater risk should anaphylaxis occur.  Skin testing remains the initial test for allergies, as RAST is expensive, takes weeks for results and cannot be used for all allergies.

Treating Allergies

There is no cure for allergies, although some people do outgrow them.  Some of them can however be easily treated, but the best solution is to limit exposure.  For some allergens, such as certain food allergies, latex allergy and allergies to medications, this may be relatively simple by avoiding them. 

Allergy symptoms can be treated medically with antihistamines or corticosteroids to stop the immune response and prevent symptoms.  Other medications are used to relieve symptoms, for example decongestants, nasal sprays and eye drops.  Hyposensitisation, or allergy shotsã?»can be used to produce tolerance to an allergen.  The person is gradually introduced to increasing levels to re-educateã?»the immune system.  This is potentially dangerous as anaphylactic shock can occur, so should only be carried out in a doctors office.  All allergy medications have side effects and so it is better to reduce allergen exposure as much as possible and use medications only when necessary.

Treating Airborne Allergies

The other major allergens, such as dust mites, mold and pollen, are so common in the environment it is difficult to avoid exposure.  There are, however, steps which can be taken to reduce exposure.  Air purifiers are very effective at removing airborne allergens from air in the home and are extremely important for asthmatics to prevent attacks due to allergen exposure. AIRGLE Air Purifiers are widely considered the best, and most effective, air purifiers on the market today.