What is Allergy: Hypersensitivity Disorders

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Allergy is a hypersensitive reaction of the Immune system of the body to a foreign or irritable substance or called an Allergen. As your Immune system practice is to keep you strong by fighting harmful substances. Allergy usually occurred from external stimuli like pollen, pet dander or food. The word allergy is usually equated with hypersensitivity but in medical terms it is said IgE- mediated reactions. It is a lifelong immune reaction which reacts when comes in contact with allergens.

In 2002, a meeting held between WHO (World Health Organization) and WAO (World Allergy Organization) in which they discussed about the prevention from the allergy and allergic asthma, where they estimated that 20% of the world suffered from IgE – mediated allergic disease, such as allergic asthma, allergic rhinitis, allergic conjunctivitis, eczema, dermatitis and anaphylaxis. asthma is more than 50% in adults and at-least 80% of children are allergic.


Hypersensitive reactions are divided into 4 types;

  • TYPE 1:  It is an Immediate anaphylactic response of the body, which is mediated by antibody-IgE and releases Histamine, its typical time is within a minute and clinical manifestation are systemic anaphylaxis, hives, asthma rhinitis conjunctivitis, allergic gastroenteropathy, etc.
  • TYPE 2: It causes cytotoxic response to the body. It is mediated by antibody- IgG, that leads to complement consider lysis of the cell which causes autoimmune hemolytic anemia and its time period is hours to days.
  • TYPE 3: It causes an immune complex response to the body, which is also mediated by antibody-IgG, which releases lysosomal enzymes, causing tissue or organ damage. its typical time is 2-3 weeks.
  • TYPE 4: It has delayed response and it is cell mediated which releases inflammatory mediators and causes contact dermatitis ,tuberculin skin reaction, etc and its typical time is 2-3 days.


Allergens are substances which irritate your immune system and cause allergy. There are usually 7 types of allergens present, which are;

  1. DRUG ALLERGEN:  Some organic or inorganic substances in drugs like penicillianaasalergens, which are not suitable for some persons, and it is mostly unknown because it is many people don’t know until they use or interact with.ht
  2. FOOD ALLERGIES: . Food allergy occurs due to deficiency of certain enzymes that help the stomach digest them, but absence makes it sometimes impossible to digest and trigger the allergic reaction. Examples are cow milk, sea food, eggs, peanuts and fish
  3. INSECTS AS ALLERGEN: Insect venom from stings of insects like bee, ants, wasps and bites of mosquito and ticks that cause reaction to the body and it is the most common type.
  4. LATEX AS ALLERGEN:  Many people have latex allergy. Products that contain latex are gloves, balloons , condoms and other natural rubber products and it causes serious health risk to life.
  5. MOLD AS ALLERGEN: Fungi like molds, mildew and mushrooms are forms of allergens. They grow indoors and outdoors and they also cause severe reactions to the body or sometimes cause anaphylaxis reaction which becomes difficult to save a person.
  6. PETS AS ALLERGENS:  Commonly found allergens as furs , feathers , woven are some examples.
  7. POLLEN ALLERGENS:  It is the most common trigger of seasonal allergies, commonly known as hay fever .


The body shows symptoms on the basis of sensitivity that how sensitive you are?  Normally reaction occurs within seconds to days or weeks. Noticeable symptoms are;

  • Rhinitis: running nose, itching of eyes, redness and pain around nose.
  • Sinusitis (inflammation of sinus): worsening headache, thick yellow mucus draining.
  • Conjunctivitis ( inflammation of transparent membranes that line your eyelid): itchy eyes, burning eyes, thick yellow discharge from eyes .
  • Asthma, coughing, sneezing, severity cause laryngeal edema with associated symptoms of wheezing dyspnea and tachypnea.
  • Impaired hearing because of Eustachian tube (canal between middle ear to the nasopharynx) drainage.
  • Eczema: intimated skin patches which is red, cracked, itchy and rough and sometimes blister form. (actopic dermatitis)
  • Hives (urticaria): is a rash like swollen, pale red bumps in color and wheel in shape bullous lesions.
  • Abdominal pain, bloating (abdominal cramp), vomiting and diarrhea.
  • Anaphylaxis: shock, hypotension, wheezing, asphyxia and cardiac arrest.
  • Compare the color of the allergic part with feet color, if you’ll feel a difference then treat it.


Correct diagnosis, counselling and test results helps the physicians to treat it.


Prick the skin with an allergic substance and wait for 15-20 minutes and notice the reaction on skin like itchiness, rashes and little high temperature in that infected area. Sometimes it is not a confirmatory test and not risky too .


It is a fast and simple test in which concentration of IgE antibodies measures, and tells that the person is allergic to something. 


It is used to detect contact dermatitis ,adhesive patches with common allergens , chemicals paste on the back and wait for 48 hours for results.


Used for detecting food and medicine that irritate your alimentary canal, in which doctor eliminate suspected allergens or give alternate to see the reaction. If the patient experiences significant improvement then take that granted for life.


When allergens initiate to the body by oral, through nose or by contact, then see the reaction. If the person can cope by himself then challenge completes, if not then other medication are applied or given to treat them.


Your doctor will give you medicines to overcome the reactions like;

  • Antihistamine: it is an antagonist drug which treats allergic rhinitis.
  • Corticosteroids: used to lower the inflammation of the body
  • Cetirizine : also an antihistamine used to treat watery and itchy eyes, sneezing and running nose. (like zyrtec) 
  • loratadine: like claritin, lorid-MD
  • Cromolyn sodium: it is anti-inflammatory.brand name like gastrocrom.
  • Decongestant.
  • Leukotriene modifiers: like singular, zyflo.

Take medication according to doctors prescription.


In this therapy, the course of several injections is injected for a few years and try to make your immune system used to it so that allergens will not irritate more and also stop allergy symptoms from occurring again.


Emergency epinephrine should be with everyone because it helps in vasoconstriction and revives your heart in conditions like anaphylactic shock or life threatening allergy.  

Don’t forget to call 911 immediately when you see any symptoms of anaphylaxis, like heavy breathing,trachechardia, low BP.


Allergies cannot be prevented but we can take care or manage ourselves by avoiding things which irritate our immune system and reaction occurs. Avoiding the food which irritates your stomach and using prescribed medication on time can help you recover and tolerate the condition.


Q. What is the most occurring allergy and how to avoid it?

Dust and pollen allergy is one of the most common allergies and it causes rhinitis or sinusitis, running nose, watery eyes and sometimes dry mouth too.

Q. What are the natural remedies to prevent allergy?

Some natural remedies are; always use a mask before going out. Use 3 times a glass of water with apple cider vinegar and lemon. Butter-bur is an European herb that helps to treat seasonal allergies and use more water that helps you to overcome your stress and make your body more hydrated.

Q. What are the complications of allergy if it lives long?

Anaphylaxis is the most serious complication but tissue damage with long irritating unknown allergy which will make severe risk in later life.

Q. Are there any side effects of immunotherapy?

Usually sneezing and nasal congestion, hives and skin rashes are common side effects with immunotherapy but not risk to life.