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Allergies

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Allergies
Summary
  • There are four main types of allergens. Inhalants, foods, injectants (bites/stings) and contact allergens.
  • Common allergy symptoms include; inflammation or swelling, hives, congestion, runny nose, conjunctivitis, sinusitis, rhinitis, nausea, vomiting and skin rashes.
  • Common food allergies include; peanuts, cow's milk, soy, seafood and eggs.
Description

Allergies are reactions experienced by some people, to substances (allergens) in the environment which are usually harmless. An allergic reaction causes the immune system to over-react to the substance. Most allergens are found in the atmosphere and may include cigarette smoke, dust, pollen etc. Other allergens include food, insect stings, medications and latex.

A person who is overly reactive to a substance that is well tolerated by most other people, is said to be allergic or atopic. The substance which causes an allergic reaction is called an 'allergen'. Antibodies are produced within the body to provide protection against allergens.

Allergic reactions occur when there is an overproduction of an antibody and the immune defences act too strongly against an allergen. This antibody binds to certain cells (mast cells) found mainly in the skin and lining of tissues of the body such as in the nose, lungs and gut. So, when an allergen is inhaled or eaten, the mast cell is activated to release substances called mediators to combat the allergen. Histamine is one of these substances which causes inflammation and tightening of the airways. Antihistamines are drugs which help to block this reaction.

There are four main types of allergens.

  1. INHALANTS:
    These include house dust mites; pollens from grasses and weeds (causing hayfever); spores from moulds; other components of house dust such as food materials and fragments from insects; cigarette smoke; air pollution; and animal fur. The house dust mite is the most common allergen in humid towns and cities.

  2. FOODS:
    Foods such as cow's milk, wheat, eggs, nuts, seafood and soy beans; drugs such as penicillin; naturally occurring or added food chemicals, such as salicylates, amines and glutamates can cause hypersensitivity reactions. See the Food allergies topic on the HealthPoint.

  3. INJECTANTS:
    Insect bites or stings; injections of antibiotics, the most common of which is penicillin; and vaccines may cause allergic reactions. A more serious allergic reaction called Anaphylaxis may occur which can be fatal if not treated promptly. (See the Anaphylaxis topic on the Healthpoint).

  4. CONTACT ALLERGENS:
    Plants; industrial chemicals and those used in handiwork and other hobbies such as glues and solvents; some cosmetics; and jewellery may all cause an allergic reaction when in contact with the skin.


Signs & Symptoms

Common allergy symptoms include; inflammation or swelling, hives, congestion, runny nose, conjunctivitis, sinusitis, rhinitis, nausea, vomiting and skin rashes 1. Whenever an allergic reaction occurs, there is tissue (cell) injury. Depending on the allergen and where it enters the body different symptoms may be experienced. Pollen, for example, when breathed in through the nose may cause symptoms in the nose, eyes, sinuses and throat. Anaphylaxis is the most severe form of allergic reaction. It results in potentially life-threatening symptoms such as difficulty breathing, hives, stomach upset or a drop in blood pressure (shock).


Intolerance vs. Allergy

Many food intolerances are mistaken for Allergies. A food intolerance is an adverse food-induced reaction that does not involve the immune system 2. A food intolerance may cause symptoms such as gastrointestinal problems e.g diarrhoea or constipation. Lactose intolerance, for example, is due to difficulty digesting the sugar in milk and is also not an allergy.

A food allergy, however, involves the immune system and can cause serious symptoms such as swelling of the tongue and the throat; difficulty swallowing; difficulty breathing; nasal congestion; runny or itchy nose (rhinitis); hives or skin rash; vomiting, abdominal cramps and diarrhoea; wheezing (this often sounds like the wheezing associated with asthma); and in severe cases, drop in blood pressure, loss of consciousness and respiratory failure (anaphylactic shock).

  • Management

    It is important to consult your Doctor to diagnose and treat this ailment. Food and chemically induced Allergies can be difficult to identify. Your Doctor may refer you to an Allergy Specialist to identify the cause. This specialist can accurately diagnose an allergy by a blood test or skin prick test. The severity of the allergy is assessed according to the test result and the person's clinical history.


    Lifestyle

    Diet Hints
    • Allergic responses to certain foods can cause very serious symptoms. It is essential to identify allergic foods so other more serious problems do not arise. Your Doctor is the person to consult for a referral to an Allergy Specialist.
    • Foods that are most commonly assoicated with allergic reactions include; peanuts, cow's milk, soy, seafood and eggs. Similar reactions can occur to some chemicals and food additives.
    • Fortunately, the majority of food allergies are not severe, and will disappear with time, particularly in children. Allergies to nuts, seeds and seafood, however, tend to persist throughout life.
    • In some cases a temporary "elimination diet" under close medical supervision will be needed. Potentially allergic foods are eliminated from the diet then reintroduced to help identify the cause of the allergic reaction.
    • Carefully read the content labels of foods in supermarkets. For example, the terms "whey" or "casein" would indicate the presence of dairy products.
    • Prepare in advance for eating away from home as this poses greater risks. For example, it is wise to inform your host or restaurant chef about your allergy and the importance of avoiding contamination of your meal with allergen. 
    • It is important to discourage a child with a food allergy from swapping food with friends.
    • Children's parties may involve sending the allergic child with their own special party food.
    • Relatives, baby-sitters and other caregivers need to be warned about the problem.  


    Vitamins/Minerals/Herbs

    A person with the potential to develop anaphylaxis should ALWAYS seek the advice of an Allergy Specialist before taking any nutritional supplements.

    • Flavonoid containing foods, supplements and herbs are thought to reduce sensitivity to allergens by reducing the levels of histamine released by mast cells 3. These include grape seed extract, quercetin and citrus fruits.
    • Bromelain (an enzyme found in pineapple) is thought to inhibit inflammation and may assist in reducing the inflammatory response triggered by allergy 4.
    • Vitamin C reduces histamine release and the sensitivity of inflammatory cells in responding to allergens 5.
    • Albizzia is a herb that has 'anti allergy' properties. It is believed to help with lowering allergy producing antibodies and reducing inflammation 6.
  • Pharmacist's Advice

    Ask your Pharmacist for advice.

    1. Try to identify the source of the problem and make every effort to avoid any known allergens 7.
    2. Follow the Diet Hints and especially the Diet for Allergies. Follow the advice of your Allergy Specialist 8. (See the Elimination Trial Diet topic on the Healthpoint).
    3. An antihistamine may be suggested by your Pharmacist. There are several brands available. Watch for any possible side effects which may include drowsiness. New products are on the market which have few side effects 9. Claratyne and Lorastyne are examples of non-sedating antihistamines which should not be used by a woman who is breastfeeding 10.
    4. If the allergy has caused a rash and the skin is not broken, your Pharmacist may recommend anti-inflammatory cream.
    5. Avoid house dust by; replacing carpet with polished boards, linoleum, cork or slate, vacuuming regularly, storing books and dust catching items out of living areas and replacing drapes with plastic blinds.
    6. Watch for allergic reactions to pets, especially cats. Remember that cat saliva which is an allergen, remains suspended in the air for up to six months 11.
    7. If you suffer from pollen inhalation consider staying indoors between the hours of 6am and noon when pollen is at high levels in the atmosphere. Wearing a mask and sunglasses while mowing or working in the garden may provide protection.
    8. If the diet is inadequate some supplements might be suggested. A person with the potential to develop anaphylaxis should seek the advice of an Allergy Specialist before taking any nutritional supplements. Vitamin C is considered by some people to have natural antihistamine properties 12. Max EPA and Evening Primrose Oil have proven anti-inflammatory properties which, if taken over a period of time, may help to reduce the severity of Allergies 13. Propolis may help to reduce the inflammation and over-reaction of the immune system which occur with allergies 14.
  • Notes

    References

    1. Wright J.V.: Healing with Nutrition. Rodale, Emmaus, Pa, 1984-Table 2: Symptoms & Diseases Commonly Associated With Food Allergy.
    2. The Food Allergy & Anaphylaxis Network. FAQ's. 2001. Available at URL http://www.foodallergy.org/queries.html. 
    3. Abdulrazzaq YM, et al. Pet ownership in the UAE: its effect on allergy and respiratory symptoms; J-Asthma. 1995; 32(2): 117-24. 
    4. Kodama M, et al. Vitamin C and the genesis of autoimmune disease and allergy (review).; In-Vivo. 1995 May-Jun; 9(3): 231-8. 
    5. Abushufa R, et al. Essential fatty acid status in patients on long-term home parenteral nutrition. JPEN-J-Parenter-Enteral-Nutr. 1995 Jul-Aug; 19(4): 286-90. 
    6. Natarajan K, et al. Caffeic acid phenethyl ester is a potent and specific inhibitor of activation of nuclear transcription factor. Proc-Natl-Acad-Sci-U-S-A. 1996 Aug 20. 93(17). pp 9090-5. 
    7. Pearce F, et al. Mucosal mast cells, III: Effect of quercetin and other flavonoids on antigen induced histamine secretion from rat intestinal mast cells. J Allergy Clin Immunol. 73:819-823, 1984. 
    8. Tausig SJ. The mechanism of the physiological action of bromelain. Medical Hypotheses. 6:99-104, 1980. 
    9. Bielory L, et al. Asthma and Vitamin C. Annals Allergy. 73:89-96, 1994. 
    10. Johri RK, et al. Effect of Quercetin and Albizzia saponins on rat mast cells. Jan-Mar 1985.Indian J Physiol Pharmacology.(29) 43.
    11. Braso-Aznar-JV; Pelaez-Hernandez-A; Etiologic role of unapparent exposure in cat allergy; Allergy. 1995 May; 50(5): 447-50. 
    12. Joral A, et al. Adverse reactions to food in adults; J-Investig-Allergol-Clin-Immunol. 1995 Jan-Feb; 5(1): 47-9. 
    13. Victorian Drug Usage Advisory Committee Respiratory Drug Guidelines. Melbourne. Therapeutic Guidelines Ltd, 1994. 
    14. Australian Medicines Handbook. Adelaide: 1998.
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