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Allergies

In April 2008, our guest expert in Le Club's Ask the Expert segment was allergy specialist Dr. Eric Leith.

Dr. Leith is in practice in allergy and clinical immunology and is affiliated with Women's College Hospital’s department of medicine, University of Toronto and Oakville Trafalgar Memorial Hospital (Halton Healthcare).

He is chair of the Canadian Allergy, Asthma and Immunology Foundation (CAAIF) and serves on the Board of Directors of AllerGen (NCE) as well as on the executive of the Canadian Society of Allergy and Clinical Immunology (CSACI), Allergy, Asthma and Immunology Society of Ontario (AAISO), and is a medical advisor with Anaphylaxis Canada.

He is a peer assessor in allergy and clinical immunology with the College of Physicians and Surgeons of Ontario (CPSO).

Dr. Leith is also a past-president of the Canadian Society of Allergy and Clinical Immunology (CSACI), a previous chief of medicine of the department of medicine at Oakville Trafalgar Memorial Hospital, a previous member of the examination board in allergy and clinical immunology for the Royal College of Physicians and Surgeons of Canada, and a previous chair of the section of allergy and clinical immunology of the Ontario Medical Association.

Here are Dr. Leith’s answers to your questions on Allergies:

Q: Is it just me or is everyone like this? When I eat fruit pineapples, cherries, apples and peaches my throat swells or tingles, it’s mild but makes me not want to eat it – fruit of all things!

A: Oral allergy syndrome is described in patients who have pollen allergy who have cross-reaction with food allergens. The symptoms are usually mild including itch and swelling of the oral mucosa of lips, mouth, tongue and throat and rarely may become more serious. If so it is called anaphylaxis rather than oral allergy syndrome.   

Patients with birch pollen allergy may react to fruits such as apple, plums and peaches and those with ragweed pollen allergy may react to watermelon.  If the food is cooked, the patient usually is able to eat without problem since cooking changes the structure of the allergen so as not to have cross-reactivity. However, a patient with food allergy and potential anaphylaxis risk, such as to peanuts, will also react even if the food allergen is cooked.  Some allergists may prescribe an injectable epinephrine to have available.

 


Q: Is there any natural product that can be taken prior to the allergy season that will lesson or stop the symptoms?

A: There are well established treatments for patients with seasonal allergy including oral antihistamines (second generation non-sedating), intra-nasal corticosteroids, anti-allergy eye drops and in patients not responding to medical therapy and a history of seasonal allergies confirmed by skin tests the option of immunotherapy. 

There are ongoing scientific research studies of future treatment options. However, many patients seek alternative treatments which, if unproven and if not submitted for scientific research studies, remain unproven and cannot be recommended. 

 



Q:
Is there anything new in the study of idiopathic angioedema? Years ago, this was my diagnosis after examination and testing by an allergist. I have never been able to avoid the triggers because I can't figure out what they are. I have recently had bouts after the spring rains.

Allegra was advised daily because my bouts were so frequent. That helped but after a couple of years there are bouts (facial, tongue, limb site swellings) despite the regular Allegra. It is as though I have a tolerance now to the Allegra. Does this disease incidence change with the age of the individual?  Also, Benadryl is effective but really makes me super tired. Is there an alternative?

A: Angioedema is a condition of swelling of the skin and mucous membranes and may be associated with urticaria (hives).  The causes may include medications such as nonsteroidal anti-inflammatory drugs (NSAIDs); angiotensin converting enzymes inhibitors (ACE inhibitors); infections; venom stings; lymph organ abnormalities; and hereditary or acquired angioedema.

After a detailed history and examination appropriate investigations are considered to determine underlying conditions. In some patients no cause is identified and it is termed idiopathic angioedema. The treatment is to remove an associated condition that may cause or exacerbate angioedema, antihistamines (second generation non-sedating preferable), corticosteroids and – if potential of anaphylaxis or involvement of the airway is present – an injectable epinephrine can be kept and used in the case of emergency. Some patients may have a self-limiting condition and others may have chronic episodic angioedema.

 


Q: Can you explain the difference between an allergy and sensitivity? Why don’t sensitivities show up on allergy tests? Should sensitivities be taken as seriously as allergies?

A: An allergic reaction (or type one hypersensitivity) involves an allergen to which a patient has been sensitized and a specific IgE antibody that binds to the allergen. Once this antibody binds to the allergen, this releases histamine into the body, which subsequently attracts other inflammatory cells and cytokines (proteins produced by white blood cells) to spread the inflammatory allergic reaction.

A sensitivity is a term that can be used to describe an observation of events where the mechanism is not well understood.  Sensitivity and allergy are terms sometimes used by lay persons to describe situations.

 


Q: What is the best treatment for grass pollen allergies? I don't seem to have allergies at any other time of the year except for mid-June to early July. At times it can be quite severe, especially when it's humid and windy. I find that the traditional over-the-counter allergy formulas actually make me feel worse. I've heard that homeopathic remedies and Chinese herbs work well for some people.

A: As mentioned in  one of the questions above, the treatment of seasonal pollen allergy such as grass includes minimizing exposure, such as windows closed with air conditioning if available, oral antihistamines, oral decongestants, intra-nasal corticosteroids, anti-allergy eye drops, and immunotherapy. Alternative therapy which has not been submitted to scientific research studies remains unproven and can not be recommended.

 



Q:
I've heard that allergy symptoms can be reduced by strengthening one's immune system. Does this approach make sense, and what is the best way to achieve this?

A: Immunotherapy may over time induce tolerance to minimize symptoms and medications required in patients with seasonal allergies but rarely may be associated with systemic reactions. There has been ongoing research to develop more effective therapies with fewer potential side-effects to treat allergic conditions. The immune system is being further understood and there have been efforts to develop biologics to enhance the immune system in certain disease states or minimize the immune response in other disease states.

 


Q: Why do I react (running nose, sneezing, watery eyes, etc.) to smells of cleaning products, perfumes, smoke, and to a cold room?  I have gone for allergy tests and the result is the usual – trees, grass, dust, pet hairs – but no mention of anything else. These reactions affect me more in my everyday life. This goes on all year. I have started going for shots for the trees and grass but I am affected almost every day. Thanks very much.

A: Rhinitis may include symptoms of sneezing, running, blockage and itching of the nose.  It may be caused by an allergic reaction to an allergen such as cat, dust mite or grass or it may be associated with an irritant reaction to irritants such as dust, smoke, household chemicals or paint fumes. Rhinitis may be classified as either allergic or non-allergic. Vasomotor rhinitis describes a condition that has symptoms similar to allergic rhinitis but the mechanism is not caused by antibodies and may be related to neurovascular (the relationship between nerves and the blood vessels) abnormalities.

 


Editor’s note: The following two questions share one answer, directly below.

Q: At 33 years of age, after chronic sinusitis for the last year, I was tested for allergies and told I was allergic to dust. What is the most effective treatment for getting rid of the sleep problems due to congestion? I can deal with pain during the day but it's the sleep that's the big issue. Thanks for your help!

Q: I often have a runny nose – while eating, when I bend down, and when I’m doing nothing I feel my nose drip. When I am outside and when I’m physically active I have to blow my nose often. This is poisoning my life, especially since I work in the food industry. Five or six years ago I went through three winters of desensitization at an allergy specialist. But my runny nose continues it seems that the situation is getting worse. Recently I had to consult an ear, nose and throat specialist due to repeated nose bleeds. I will have to undergo a cauterization soon.  Are these problems allergy-related and what can I do about it?

A: Some patients with rhinitis may have associated involvement of the sinuses.  The mechanism may be allergic and non-allergic.  Acute sinusitis may be caused by a viral or bacterial infection, and if bacterial, may require antibiotics.  Some patients with allergic rhinitis may also have involvement of the sinuses.

Chronic rhinosinusitis is a condition that involves ongoing inflammation of the nose and sinus and may be classified into chronic rhinosinusitis with or without nasal polyps. CT scans of the sinuses may help to identify this condition, and intra-nasal corticosteroids are often helpful. Patients with these conditions are assessed by allergists and may require referral to otolaryngologists (ear-nose-and-throat specialist) if symptoms persist in spite of medical treatment to rule out structural causes.


Q: What is the difference between an allergy and food intolerance? How does the body react to each in terms of antibodies?

A: Food adverse reactions describe any adverse reaction to a food.  An allergic reaction infers there is something called an IgE mediated hypersensitivity to a food allergen such as peanut that may result in an anaphylactic reaction (e.g. hives, shortness of breath, itch, throat swelling and low blood pressure). This often requires emergency treatment including epinephrine injection.

Oral allergy is also an IgE mediated allergic reaction (see the first question). An adverse reaction that is immunologic may include eosinophilic eosophagitis and celiac disease and a non-immunologic reaction may include lactose intolerance.

 


Q: I would like to know if the medication Neurotin can interfere with allergy tests and if so, how?

A: Skin testing may be affected by patients who are on antihistamines or medications with antihistamine properties such as some antidepressants.  A negative and positive (usually histamine) control are also included with the skin test to help clarify the patients reaction to the allergens tested.  Also, severe eczema may affect the interpretation of skin tests.

 


Q: If a person who is supposed to be allergic to peanuts risks eating them but does not have a reaction (for 48 hours) can she conclude that she is not allergic to peanuts and continue eating them?

A: A person may be skin test or specific IgE positive to an allergen. This has to be interpreted in light of the patient’s history to help determine whether that patient is also clinically sensitive to the allergen and at potential risk of anaphylaxis. Skin tests and/or specific IgE to allergens are only recommended in patients where there is suspicion of allergic cause of a medical condition and in some cases because of a family history of allergy.

 


Q: I am wondering what suggestions you have for dealing with cat allergies when you own a cat (other than getting rid of the cat!).  What kind of things can you do around the house?  What do you think of air filters?

A: The best treatment for an allergic reaction to an animal is to remove the allergen from the patient’s environment. However, this may not be possible in many situations. Therefore, medical treatment may be undertaken and if the patient is not responding then in selected clinical situations, immunotherapy may be considered.

 

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