Common IgE Allergy Symptoms:

 One or more allergen-specific IgE antibody tests are usually ordered when a person has signs or symptoms that suggest an allergy to one or more substances. Signs and symptoms may include:

  • Hives
  • Atopic Dermatitis Disease
  • Eczema
  • Red itchy eyes
  • Coughing, nasal congestion, sneezing
  • Asthma
  • Itching and tingling in the mouth
  • Abdominal pain, or vomiting and diarrhea

How is it used?

 The allergen-specific IgE antibody test is a blood test used to screen for an allergy to a specific substance or substances if someone has acute or chronic allergy symptoms. This is especially true if symptoms are recurrent and appear to be tied to triggers, such as exposures to particular foods or environments, and if other family members are known to have allergies. In some cases when the allergy is severe and affects the nasal passage directly patients are referred to an ent for a better diagnosis.

A variety of different types of allergy tests may be performed by exposing a person to different substances. The usefulness of these tests, however, can be affected by skin conditions, such as significant dermatitis or eczema, and by medications, such as antihistamines, steroids (like cortisone, hydrocortisone, prednisolone, methylprednisolone, and ) and certain anti-depressants.  With some tests there is also the potential for severe reactions, including a severe reaction that may be life-threatening. In these cases, the allergen-specific IgE antibody test may be ordered as an alternative, as it is performed on a blood sample and does not have an effect on the person being tested.

The allergen-specific IgE antibody test may also be done to monitor immunotherapy (desensitization) or to see if a someone has outgrown an allergy or inflammation like Atopic Dermatitis Disease.  It can only be used in a general way, however, as the level of IgE present does not correlate to the severity of an allergic reaction, and someone who has outgrown an allergy may have a positive IgE for many years afterward.

The RAST Test:

A RAST (RadioAllergoSorbent Test) is a blood test done to look for Immunoglobulin E (IgE), an allergic antibody.  IgE is a protein in our body that attaches to food proteins to start an IgE mediated allergic reaction.  To have an IgE mediated allergic reaction, you need to have IgE to the food in question.  A RAST test looks for IgE in your blood. This test can’t tell you if you will react or how severely you will react, but tells you that you have IgE against the food.

A negative test, especially in IgE antibody mediated food allergy, is very reliable to suggest that that patient may not have an allergic reaction or a serious life threatening reactions. A positive test really requires that you see your physician to correlate your clinical history back with that positive test to understand if that food should be taken out of your diet and avoided to prevent future allergic responses.

Skin Tests are the Most Common (Specific Methods Vary):

The prick test (or scratch) test is one of the most commonly used tests by allergists. The skin is pricked so the allergen (allergy causing) substance goes under the skin’s surface. Then a small amount of suspected allergen substances are applied on the “scratched” skin of the forearm, upper arm, or the back most commonly. A health care provider closely evaluates the skin for signs of a reaction: such as swelling and/or redness at the site which can indicate if a treatment is needed. Reactions to these allergens usually occur within 15-20 minutes or less. Multiple allergens can be tested at the same time.

Intradermal skin test is a method very similar to the scratch test. It involves injecting a small amount of allergen under the skin and watching for a classic “allergic” reaction at the injection site.  It is often used when testing is being done to find out if you are allergic to something specific, such as bee venom or penicillin.

Patch testing is a method sometimes used to diagnose allergic reactions on the skin but, you can get a complete diagnosis at a dermatology clinic. Possible allergens are taped (using various methods) to the skin for 48 hours. The health care provider will look at the area (under the patches) in 24 hours and again 24 hour later after the first evaluation of the sites.

Skin tests are most useful for diagnosing:

  • Food allergy
  • Mold, pollen, animal, and other allergies that cause allergic rhinitis and asthma
  • Penicillin allergy*
  • Venom allergy
  • Allergic contact dermatitis

Allergy Provocation Testing:

Provocation (challenge) testing involves exposing a person to a suspected allergen under controlled circumstances. This may be done in the diet or by breathing in the suspected allergen. This type of test may provoke severe allergic reactions like anaphylaxis which is a severe, whole-body allergic reaction to a chemical that has become an allergen. After being exposed to a substance such as bee sting venom, the person’s immune system becomes sensitized to it. On a later exposure to that allergen, an allergic reaction may occur. This reaction happens quickly after the exposure, is severe, and involves the whole body.  Challenge testing should only be done by a doctor.

Anaphylaxis Symptoms:

  • Symptoms develop rapidly, often within seconds or minutes. They may include the following:
    • Abdominal pain or cramping
    • Abnormal (high-pitched) breathing sounds
    • Anxiety
    • Confusion
    • Cough
    • Diarrhea
    • Difficulty breathing
    • Difficulty swallowing
    • Fainting, light-headedness, dizziness
    • Hives, itchiness
    • Nasal congestion
    • Nausea, vomiting
    • Palpitations
    • Skin redness
    • Slurred speech
    • Wheezing
  • Signs include:
    • Abnormal heart rhythm (arrhythmia)
    • Fluid in the lungs (pulmonary edema)
    • Hives
    • Low blood pressure
    • Mental confusion
    • Rapid pulse
    • Skin that is blue from lack of oxygen or pale from shock, Pure Canned Oxygen can help you with that!!
    • Swelling (angioedema) in the throat that may be severe enough to block the airway
    • Swelling of the eyes or face
    • Weakness
    • Wheezing

The health care provider will wait to test for the specific allergen that caused anaphylaxis (if the cause is not obvious) until after treatment.

Anaphylaxis Treatment

Anaphylaxis is an emergency condition requiring immediate professional medical attention. Call 911 immediately.

Check the person’s airway, breathing, and circulation (the ABC’s of Basic Life Support). A warning sign of dangerous throat swelling is a very hoarse/whispered voice or coarse sounds when the person is breathing in air. If necessary, begin rescue breathing and CPR.

  1. Call 911.
  2. Calm and reassure the person.
  3. If the allergic reaction is from a bee sting, scrape the stinger off the skin with something firm (such as a fingernail or plastic credit card). Do not use tweezers — squeezing the stinger will release more venom.
  4. If the person has emergency allergy medication on hand, help the person take or inject the medication. Avoid oral medication if the person is having difficulty breathing.
  5. Take steps to prevent shock. Have the person lie flat, raise the person’s feet about 12 inches, and cover him or her with a coat or blanket. Do NOT place the person in this position if a head, neck, back, or leg injury is suspected, or if it causes discomfort.


  • Do NOT assume that any allergy shots the person has already received will provide complete protection.
  • Do NOT place a pillow under the person’s head if he or she is having trouble breathing. This can block the airways.
  • Do NOT give the person anything by mouth if the person is having trouble breathing.

Paramedics or physicians may place a tube through the nose or mouth into the airways (endotracheal intubation) or perform emergency surgery to place a tube directly into the trachea (tracheostomy or cricothyrotomy).

The person may receive antihistamines, such as diphenhydramine, and corticosteroids, such as prednisone, to further reduce symptoms (after lifesaving measures and epinephrine are given).

Expectations (prognosis):

Anaphylaxis is a severe disorder that can be life-threatening without prompt treatment. However, symptoms usually get better with the right therapy, so it is important to act right away

IgG  Allergies:

IgG allergy blood testing can be a useful guide for structuring elimination diets in many chronic conditions.  Frequently, those with neurological, gastrointestinal, and movement disorders may suffer from IgG food allergies. These people may continue to eat offending foods unaware of their potential harmful effects.  IgG antibodies provide long term resistance to infections and have a much longer half-life (stay in the blood longer) than the traditional IgE allergy antibodies. Symptoms from IgG allergies may occur hours or sometimes days after the offending food has been eaten.  This makes it hard to identify what foods or substances may be setting off a delayed allergic response without IgG lab testing.   The elimination of IgG positive foods can improve symptoms of irritable bowel syndrome, autism, AD(H)D, cystic fibrosis, rheumatoid arthritis, and epilepsy according to numerous clinical studies*.

IgA Allergies:

IgA antibody testing provides additional information to identify suspected food or inhalant triggers; IgA represents a primary immune reaction with a half-life of about 5-6 days when compared to IgG, which has a half-life of about 20-24 days.

Both IgA and IgG may be present in a variety of chronic inflammatory disorders. Unfortunately there is no hard and fast rule on when to order IgG versus IgA testing, or when to do both, but assessing both antibodies offers a comprehensive picture for the patient.

Measuring reactions to foods is a complex science and has traditionally involved measuring antibodies. Antibodies are produced by your immune system in response to things that it is attacking.  Antibodies can be found in the blood through a routine blood draw.

Traditionally, labs have made available two different types of antibody tests with regard to reactions to foods. These were the IgG and IgE antibodies. Other antibodies are known to exist and can be relevant when measuring food reactions, in particular IgA antibodies.

This test allows us to evaluate whether or not you have an IgA reaction to many foods. These are the same foods to which you may have previously been tested for IgG and IgE reactions.

IgG and IgE tests have proven to be extremely helpful for solving the health concerns of many, but this new and useful IgA lab testing tool can detect allergies missed by other types of evaluations.

Elimination Diets:

The basic elimination diet first removes all potential food allergens from the diet, and then re-introduces these foods one at a time. This process should always be undertaken in consultation with your physician.

When undertaking an elimination diet, it is advisable to keep a food journal, and log all food items and amounts as accurately as possible – along with any symptoms experienced. This can help to isolate food allergies or intolerances.

Basic Elimination Diet Example:

  1. Eliminate the following foods from the diet for a period of 7 days to a month:
  • Dairy products, including cheese. [Instead, use soy milk and soy cheese; rice milk, rice-based ice cream.]
  • Egg and egg-containing products.
  • Food products containing gluten, such as wheat and wheat-based products (including pasta), and barley, oat or rye grains. (Alternative grains could be brown rice, buckwheat, spelt, millet, potatoes or sweet potatoes).
  • Citrus fruits.
  • Corn and corn-containing products.
  • All processed foods
  • All *caffeine.

*Suddenly stopping some foods (such as caffeine) can result in withdrawal symptoms or detoxification symptoms (typically headaches) – however this should only last a few days.

  1. Reintroduce one food or food group to your diet roughly every 5 days.
  • The reintroduction period may allow sufficient time to determine some intolerances.
  • There are drawbacks to elimination diet such as:
    • Patient compliance, it is difficult to do this right
    • Some sources report it can take up to 7 days for a delayed food reaction to occur.  Using the 5 day reintroduction period could skew results.
    • There could be other interfering factors and an “intolerant” food is falsely identified (i.e. the person came in contact with a virus at the same time as they reintroduced “dairy” the person assumes their “allergy” symptoms are from the reintroduction of dairy, but in reality it was just a coincidental gastrointestinal virus and the person had no “allergy” or “intolerance” to milk, but now thinks that they do).
    • The person may find one or more truly “intolerant” foods, but stops the elimination diet before finding all the foods that could be identified with this method.   Thus, the person’s health may only partially improve or not improve at all then they blame their aliments on other causes when food allergy or intolerance is still a major undiagnosed factor.

ALCAT Testing:

The ALCAT Test is NOT an “allergy” or IgE test. The ALCAT is an effective and comprehensive sensitivity/intolerance test.  The test identifies reactions to over 350 foods, chemicals and other substances associated with inflammation that are linked to chronic health problems like migraines, aching joints, fatigue, gastrointestinal disorders, eczema, obesity, etc.

The antigens that are selected are reacted in the ACLAT analyzer against white blood cells in your blood sample.  Therefore the positive reaction occurs in the analyzer and NOT in your body.  This type of testing has some advantages over IgG tests, because IgG testing relies exclusively on one immune pathway.  High food specific IgG titers are indicative only of exposure, not necessarily intolerance.  Therefore high frequency of consumption or over exposure may lead to false positives.

Learn more about ALCAT Testing…

References for Skin test section.

Bernstein IL, Li JT, Bernstein DI, Hamilton R, et al. American Academy of Allergy, Asthma and Immunology; American College of Allergy, Asthma and Immunology. Allergy diagnostic testing: an updated practice parameter. Ann Allergy Asthma Immunol. 2008 Mar;100(3 Suppl 3):S1-148.

Demoly P, Bousquet J, Romano A. In vivo methods for the study of allergy. In: Adkinson NF Jr, ed. Middleton’s Allergy: Principles and Practice. 7th ed. Philadelphia, Pa: Mosby Elsevier; 2008:chap 71.

Gober MD, DeCapite TJ, Gaspari AA. Contact dermatitis. In: Adkinson NF Jr, ed. Middleton’s Allergy: Principles and Practice. 7th ed. Philadelphia, Pa: Mosby Elsevier; 2008: chap 63.

*References for IgG section.

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