Allergy Information

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Allergy Information

What is Allergy?

Allergy is an adverse immune reaction to an allergen (or protein) in our environment, which is normally harmless to the non-allergic person. Or simply put it is hypersensitivity to foreign substances which are normally harmless but which produce a violent reaction in the allergy sufferer.

Allergy develops after repeated exposure to the causative allergen. Sensitization takes place on initial exposure (a process that may take up to 6 weeks to develop) and no adverse reaction appears to occur during this sensitization. On repeated allergen exposure, the full-blown allergic reaction will occur some time later.

During initial exposure (sensitization), Antibodies (IgE) are produced by our white blood cells and on re-exposure these IgE antibodies bind the allergen and attach to Mast Cells, which release Histamine. Histamine triggers the beginning of the Allergic Reaction, which may manifest with anything from a mild itch of the skin, Wheeze, anaphylaxis and to death. Late phase reactions also may follow 6 to 24 hours later with Inflammation and tissue swelling.

Symptoms of Allergy:

It may present as mild itching of the skin, wheeze or even progress to full-blown reaction and death
The most common of these problems is hay fever or allergic rhinitis in which the patient suffers from nasal congestion, running nose, sneezing, nose and eye itching and a post nasal drip. Patients also complain of loss of smell, loss of taste and nasal bleeding.
Typical allergic reactions are hay fever, asthma, allergic cold, recurrent sinusitis digestive disturbances, conjunctivitis, urticaria, eczema, allergy to Medication such as Penicillin.
Almost any substance can cause allergy in an individual. Common allergens include house dust, pollen, certain foods, especially milk, wheat and eggs, pollens, moulds, cosmetics and certain food additives.
Exposure to house dust, a major cause of year long suffering, intensifies as people head indoors for winter. Symptoms of an allergy to house dust are often mistaken for colds as they include running nose, nasal congestion, itchy and watery eyes.
House dust has been suspected as an allergen for many centuries, but was formerly seen as a simple substance. Today, its complexity is recognized – a conglomeration of living and non-living material including fabric fibers, animal dander, food particles and insect remains.
“Mattresses contain the highest concentration of dust mites, whose primary food source is flakes off human skin. The tiny creatures are also found in pillows, clothing, carpeting and upholstered furniture.”
Most people cannot control the dust conditions where they work or spend their daytime hours, but to a large extent everyone can eliminate dust from their bedroom. This is the single most important and effective step in treatment but it can become a costly exercise.
When symptoms suggest an allergy to dust mites, it will be less expensive to see an allergist for testing for the specific allergen than to entirely refurbish the bedroom on the suspicion that dust is at fault.

Who gets Allergy?

Only a small proportion of the population exposed to an allergen will develop an allergic reaction. Some families trend to develop allergic sensitization because of genetical transmission.

Why did I become Allergic?

The cause of allergy seems to be an entangled web of 3 factors – genetic predisposition, environmental triggers and locally found protein allergens.
Your genetic background plays a major role – family history of allergies is highly significant, smaller families with fewer children favour the development of allergy. Males are more likely to develop allergies than females, and prenatal maternal diet and smoking seem to play a role. Obesity also seems to be a risk factor for developing allergies.

The home environment in the first year of life is very important. Parental cigarette smoking triggers allergy, Infant diet and early introduction of allergenic foods may play a role. Air Pollution has been implicated; early use of day-care institutions, early use of broad spectrum antibiotics and birth just before the spring pollen season all seem to promote allergic sensitization. Living near a farm especially livestock farming seem to prevent allergies developing. This highlights the “hygiene theory”, whereby children living the so-called “clean western lifestyle” are at greater risk for developing allergy. Recent studies suggest that heavy exposure to dog and cat allergens in the home may actually prevent allergies developing in infants (they suggest having two or more pets in the home!)
And finally, modest exposure to the local aeroallergens and allergenic foods in conjunction with the other factors leads to sensitization in early life and clinical allergy then develops. Evidence now exists for very high allergen exposure during early life having a “protective” effect (for example to cats and dogs). However, minimal exposure during the first year of life is still the recommended “rule of thumb” for allergy prevention.

The Allergic March.

The Allergic March is the term used to describe the chronological progression of one clinical manifestation of allergy to the next. Early life allergy under the age of 3 years usually involves eczema and food allergy, this usually resolves as asthma develops in the middle childhood years. As asthma begins to stabilize, allergic rhinitis becomes a common manifestation of allergy in the adolescent years. Asthma often returns at about the age of 40 just as Hay fever is settling down.

Pseudo-allergic Reactions

Reactions to food additives such as Colouring agents, Preservatives and Flavorings are not IgE mediated, their mechanism is largely unknown.

Food Allergy:

Allergic reaction to foods varies from person to person. One particular food when allergic to somebody, you may not have the same type of allergic reaction. Allergy is there in genes.
Food allergic reactions may vary from immediate itching or swelling of the lips and/or tongue, to hives, coughing and wheezing. These reactions usually happen within a few minutes after eating the food, sometimes up to an hour. Sometimes food allergies may cause stomach cramping and diarrhoea hours later.

Food allergies can be life-threatening, especially if one is allergic to shellfish or peanuts. You know the icon of martial arts Bruce lee died of some food allergy, a form of shellfish used by Chinese for headache caused the death of the real hero.
Unfortunately, there are no safe and effective forms of allergy treatment for food allergy at this point of time. The only treatment is to avoid them.

What is “food intolerance”?

You must be careful to differentiate between “food allergy” and “food intolerance.” Per example, people have gastrointestinal symptoms upon eating milk products that means they are having lactose intolerance which is causing the symptoms. Other examples of food intolerance include a runny nose from eating spicy foods or headaches from drinking wine.

Environmental Allergy:

Your home, workplace, school or outside environment may contain substances that can cause an allergic reaction. These environmental allergens are

  • Dust.
  • Dust Mites.
  • Animal dander (mostly cats, dogs).
  • mould spores or pollen.

Pollen allergies usually occur in certain seasons when more concentration of pollen exists in the environment, and is called seasonal allergy. Other substances cause allergy problems all the year called perennial allergy.

Allergy treatment becomes harder as the true allergy to dust mites, mold or pollen is superimposed on the non-allergic effects of the pollution, ozone and humidity. That means you should pay equal attention to avoid dust mites that you are allergic to, and to avoid non-allergic triggers (e.g. cigarette smoke, perfume, etc.) and to seek medical help.

Drug Allergy:

Drug allergy is also a common allergic reaction that many people experience to prescription and over-the-counter medicines. Adverse allergic drug reactions present with body rashes, itching, swelling and wheeze.
Adverse drug reactions can be divided into three groups:
Not related to the drug at all: these are but coincidental and related to factors other than the drug. Rashes, headache or nausea are associated with the disease and not the medication.
Side effects: these are caused due to taking excess dose or due to interactions between other medicines taken at the same time.

Less common and unpredictable reactions: allergic reactions that involve the immune system that may be either immediate or delayed.

Drugs which cause allergies:

  • Allergic drug reactions may vary from minor rashes to severe anaphylactic reactions. Common
  • medications causing allergies.
  • Antibiotics – penicillin, cephalosporins, sulphonamides, tetracycline, chloramphenicol, quinolones.
  • Aspirin and anti-inflammatory drugs.
  • heart and blood pressure drugs – ACE inhibitors, quinidine, amiodarone, methyldopa.
  • aspirin-related drugs – diclofenac, ibuprofen, naproxen, indomethacin.
  • radio-contrast fluids given intravenously during x-ray.
  • anaesthetic drugs – muscle relaxing drugs, thiopentone, halothane.
  • morphine-type opiate family – morphine, pethidine and codeine.
  • cancer chemotherapy drugs – cisplatin, cyclophosphamide, methotrexate.
  • antiseptic solutions – chlorhexidine, iodine.
  • vaccines such as tetanus toxoid and diphtheria vaccine.
  • preservatives and colourings in medication such as sulphites, benzoates, parabens and tartrazine.
  • Anti-epileptic, anti-tuberculosis medication, heparin, insulin, enzymes and latex.

Why Drug allergy testing is difficult:

To confirm a drug allergy, initially intradermal skin testing has to be performed followed by a specific Drug Challenge test in a hospital setup. This procedure is very time consuming and expensive and may trigger a more severe allergic reaction and lead to more complications.

What are Drug Allergy Symptoms:

Most drug allergic reactions occur rapidly and may cause body rashes, itching or swelling. Sometimes a severe life-threatening drug allergic reaction may occur causing fever, joint pains and generalised skin blistering with peeling. It may occasionally progress to life threatening anaphylaxis and even death. Delayed reactions can occur later after 2 weeks after the drug exposure with generalised skin rash and swelling and damage to vital organs such as the kidneys, liver and blood cells.

Drug allergy treatment:

Stop the implicated drug immediately, followed by strong antihistamine medication and then consult your doctor or nearby physician immediately.
Prevention of drug allergies
If you are allergic to a group of drugs like penicillin or aspirin, then all other members of that group should be avoided. Use the alternative medications. And always inform your doctor when you meet him for any heath problem purpose.


Anaphylaxis or anaphylactic shock is a sudden catastrophic allergic reaction that usually occurs within minutes of exposure to the offending allergen and involves the whole body. Insect stings, shellfish, nuts and medication are common causes of this type of severe allergic reaction.
The first documented evidence of anaphylaxis was in 2641 BC, when King Menes of Egypt died from a Wasp sting.
About 1 in 1000 people attending Emergency of hospitals are because of some form of anaphylactic reaction. The number of new such cases seems to be rapidly increasing day by day possibly because of changes in our life style, diet and environment. Nut Anaphylaxis was first documented only 20 years ago.

Anaphylaxis causes:

Though one cannot find the exact cause of anaphylaxis, we know that the most common cause of anaphylaxis is from food allergens like nuts, peanuts, eggs, milk, fish and shellfish. These foods account for 90% of cases of food induced anaphylaxis. Peanuts and tree nuts like Almonds, Walnuts are most likely to provoke a severe allergic reaction. Sometimes drugs such as penicillin, codeine and aspirin may cause anaphylaxis. Medicines like muscle relaxants, antibiotics, x-ray contrast medium and injectable medications including anaesthetic agents may also cause this reaction.
Some people will have so severe reaction that even eating small amount of that particular allergic food can cause anaphylactic shock.
Exercise Induced Anaphylaxis occurs when exercising shortly after ingesting the allergic foods like wheat, apple, hazelnut, squid or chicken.

Anaphylaxis symptoms:

Anaphylaxis is an emergency condition and should be treated as an emergency as the symptoms of breathlessness and shock develop so rapidly that if you not treat it on time, it may lead to disaster. Emergency treatment consists of an injection of adrenaline or epinephrine, which raises blood pressure instantly, relieves breathlessness by reducing swelling of soft tissues in the throat. the affected people normally recover very quickly once the adrenaline is given. They should also be given immediately a dose of antihistamine and a short course of steroid tablets to prevent the recurrence of the reaction (biphasic response).

If you are a known anaphylactic person, be sure that having Adrenaline Injector all the time with you 24×7. In future and use it immediately whenever required as delay puts you at risk of collapse and death. Although people carry adrenalin auto injector, the common cause of death is failure to use it. So be ready with full information and knowledge about it and be daring enough to use it with a trained practice of self-administration. Always take antihistamines like levocetrizines and monitor the situation for a few minutes before taking adrenaline as milder symptoms usually resolve over the next few minutes. And later seek for doctor’s help at any emergency care of a hospital for at least 4 hours for observation.

What can you do at an Anaphylaxis Emergency:

If the person is conscious and having mild symptoms of breathing difficulty, help him to get medications.
If the person is shocked with low blood pressure, they should be kept lying flat with their legs rose.
If the person is unconscious, check their airways and breathing and kept them in the recovery position left or right turning. Check for asthma inhaler, if there, administer it. Check for a preloaded adrenaline syringe; inject it into the muscle of the thigh. And call emergency helpline for ambulance.


Asthma is a chronic inflammatory disease that makes your airways (bronchial tubes) particularly sensitive to irritants or allergens. During an asthma episode, an individual might experience shortness of breath or wheezing or tightening in the chest or cough leading to difficulty for the asthma patient to move the breathing air in and out of the lungs.
Asthma affects people of all ages and is closely related to allergy. However, it is commonly seen in children and reoccurred again in elderly.
Triggers of Asthma

What actually triggers asthma can vary greatly from person to person. Commonly allergens, but may also be such other environmental factors as:

  • Air pollution.
  • Dust mites.
  • Tobacco smoke.
  • Strong odours.
  • Wood smoke.
  • Pets.
  • Mold.
  • Weather changes.
  • Stress or illness.
  • Emergency Treatment.
  • See anaphylaxis.