News/Developments   Medical Conditions   Search About Us  |  Contact Us  |  Sign In  |  Create Account 
 
 

Allergy


By Talsk Research's Physician Group


Overview

An allergy is an abnormal reaction of the body’s immune system that occurs in response to generally harmless substances such as pollen, dust, certain foods, mold, animal dander, which are referred to as triggering factors or “allergens”. In a person with allergies, the oversensitive immune response fights off the allergens and in the process releases chemicals such as histamine which can cause symptoms that can vary anywhere from itchy and runny nose, itchy and watery eyes and itchy palate, cough, skin rash and hives to airway obstruction or anaphylaxis needing emergent treatment.

Some of the common types of conditions caused by allergies include hay fever, asthma, eczema, contact dermatitis (skin reactions), conjunctivitis (pink eye), sinusitis and occasionally a life threatening reaction called anaphylaxis. The timing of the symptoms is usually related to the presence of triggering factors in a particular season or location. Symptoms appear seasonally if allergies are due to pollen or weeds and are nocturnal if the triggering factors are dust mites.


Causes

In response to the presence of the allergens, the body’s defense mechanism produces special type of protein (antibody - immunoglobulin) to attack the invading material. This in turn leads to other blood cells to release more chemicals like histamine (a substance that dilates blood vessels and makes the vessel walls abnormally permeable), which together cause the symptoms of an allergic reaction.

Some of the common allergens include:

  • Dust mites

  • Grass and tree pollen

  • Pet hair or skin flakes

  • Fungal or mold spores

  • Food : milk, eggs, wheat, soya, seafood, fruit and nuts, shell fish

  • Wasp and bee stings

  • Certain medication such as penicillin and aspirin

  • Latex

  • Household chemicals

  • Tobacco smoke


Risk Factors

Family history of allergies is the strongest risk factor for allergies. Although the exact role of environment is unknown, it does have a significant effect in the development of allergic reactions. Some of the specific risk factors listed below are not proven but have been noted to be frequently associated with the allergic reactions.

Food allergy:

  • Mother’s diet during pregnancy and breastfeeding

  • A Cesarean delivery, during which the baby will not get exposed to the beneficial bacteria found in the birth canal that aid in digestion.

  • Exposure to tobacco smoke

  • Multivitamin intake

  • Intake of medicines that control acidity in stomach

Anaphylaxis:

  • If a person has experienced anaphylaxis before, his chances of getting another one increase and the attack can be more severe than the previous one

  • People with a history of asthma

  • Family history of anaphylaxis

Hygiene effect:

Recently there has been growing interest in studies showing the relation between children growing up in urban and cleaner environments (using antibacterial soaps and hand disinfectants and thus not being exposed to the allergens) and thereby not building resistance to the same – leading to an increase in the incidence of allergies and asthma.


Symptoms

Symptoms generally depend on the type of the allergen, the part of the body in contact with the allergen, and the immune response a particular person might have to the allergen. The time from exposure to the allergen and the development of the reaction usually determines the severity of the symptoms. Quick reactions generally lead to severe symptoms. This is a list of some of the symptoms a person with allergies might experience:

  • Red and generally itchy bumps on skin (hives), especially over the neck and face

  • Itching of the mouth, lips, tongue, throat, eyes, skin

  • Nasal congestion and runny nose

  • Tickle in the throat

  • Skin rashes or eczema (scaly skin which may peel and blister)

  • Watery, Itchy and red eyes (allergic conjunctivitis)

  • Flushing or redness of the face

  • Difficulty in breathing, wheezing or asthma

  • Difficulty in swallowing

  • Abdominal pain or cramps with or without diarrhea

  • Nausea and vomiting

Anaphylaxis or a severe and explosive allergic reaction involving the whole body and can include life threatening symptoms such as

  • Swelling of the throat and airways making breathing very difficult

  • Swelling of the face, eyes, tongue, and lips resulting in hoarseness

  • Fear or feeling of apprehension or anxiety

  • Palpitations

  • Dizziness or light-headedness

  • Loss of consciousness


Diagnosis

A detailed history of the patient’s symptoms and their timing, environmental exposures, personal and family history and a physical examination will help the doctor a great deal in diagnosing allergies - as the testing while being very helpful may not provide a complete picture.

Some of the questions that a doctor might have are:

  • Any history of previous allergic reactions, triggers, and other health conditions

  • About home and work environment

  • The type of symptoms, their onset, duration, and course

  • Whether the symptoms are seasonal or last year-round

  • Whether the symptoms occur outdoors or indoors

  • Whether the symptoms get worse around pets

  • Whether exercise brings on or worsens the symptoms

  • Smoking history, if any and family history of smoking

  • Whether the symptoms interfere with daily activities or interrupt sleep

  • History of any past medications or treatment including any current medications, herbal supplements vitamins that are being taken

The doctor may administer some allergy tests to determine the sensitivity to specific allergens and may require you to stop taking medications such as antihistamines which are used to treat allergies before testing.

Skin Tests

  • Prick test: This involves placing a small amount of allergens on the skin and pricking the area, so that the allergen goes under the skin surface. Results are seen within minutes.

  • Intra dermal test: This involves injecting a small amount of allergen into the skin to find out allergic reactions against something specific, like bee venom or penicillin. Results are seen within minutes.

  • Patch test: Possible allergens are taped to the skin for 48 hours and the area is examined for redness and swelling in 24 hrs and 48 hrs.


Elimination-type Test

This test is usually used to check for food allergies.

  • Foods causing allergic symptoms are removed from the diet for several weeks and then slowly re-introduced one at a time while the person is being monitored for signs and symptoms

Blood Tests

The test is carried out on a small sample of blood which is usually taken from a vein in the arm with a fine needle and a small syringe. This causes minimal discomfort.

  • Sample of blood is taken to measure the amount of antibodies such as immunoglobulin E that are present in high levels in patients with allergies. This test may be used when skin testing is not helpful or cannot be done.

Provocation

This (challenge) testing involves exposing a person to a suspected allergen.

  • Involves inhaling a small amount of an allergen or taking the allergen by mouth

  • Challenges are done mostly with potential food or medication allergies

The allergic reactions can be very severe and a doctor should oversee this type of testing.

Treatment and Prevention

Avoiding allergens should be number one priority in treating allergies but since that is not always possible an attempt to reduce the exposure to the allergens should be made. Following are some precautions one might want to consider depending on the triggering factors -

    • Keep the house and surroundings clean

  • Use a vacuum cleaner fitted with a HEPA (high efficiency particulate air) filter

  • Limit contact with pets as much as possible

  • Bathe and Groom pets at least once every week

  • Check for any mold in the house

  • Carefully check the label of a food product for the list of ingredients, this will help in avoiding an allergic reaction

  • Care to be taken when eating out if allergic to certain foods

  • Check weather reports for the pollen count and stay indoors when the counts are high

  • Breastfeeding babies as long as possible might help proper development of their immune systems.

  • Always carry a self injection adrenaline kit if there is a history of anaphylaxis

  • Carry a ‘medical alert card’ or ‘bracelet’ to avoid future accidental prescription to any medicine that could cause allergic reactions

Although medications cannot cure allergies, they can ease the symptoms such as a runny nose, itchy mouth, sneezing and asthma associated with allergies. Though most treatments are available over the counter, it is always safe to ask your doctor for advice before starting to take any new medication.

  • Antihistamines: Drugs that combat the histamine released during an allergic reaction by blocking the action of the histamine on the tissues. First generation antihistamines like Chlorpheniramine and Benadryl (Diphenhydramine) can cause drowsiness but second generation antihistamines like Claritin, Zyrtec, Allegra are less inclined to cause drowsiness and are very much effective when taken throughout the allergy season.

  • Antihistamine nasal sprays : Astelin is a nasal spray that can help relieve nasal symptoms without affecting other parts of the body

  • Oral decongestants: Pseudoephedrine or Sudafed is a very common oral medication used to relieve sinus and nose congestion.

  • Nasal Decongestants: Nasal sprays such as Afrin relieve congestion but only provide temporary relief and should be used sparingly due to their tendency to cause rebound congestion and other side effects such as increasing blood pressure and restricting urine flow.

  • Different combinations of antihistamines and decongestants both orally and as nasal sprays are available and work very effectively. Claritin-D, Allegra-D, Tylenol Allergy and Sinus are some examples.

  • Corticosteroid nasal sprays such as Flonase and Nasonex reduce inflammation of the nasal mucosal lining and if taken regularly can significantly reduce the need for antihistamines and decongestants

  • Antihistamine eye drops like Patanol and decongestant eye drops such as naphcon and Vasocon reduce itching and tearing of eyes but can have severe side effects if overused.

  • Inhaled steroids and bronchodilators for symptoms related to allergic asthma

  • Leukotriene inhibitors such as Singulair specifically block the mediator chemicals called Leukotrienes produced by the body in response to the allergens which are responsible for most of the allergy symptoms.

  • Allergy shots or Immunotherapy the doctor injects small doses of suspected allergens under the skin. This helps the body "get used to" the allergen, which can result in fewer or less severe symptoms but the treatment usually lasts a few years.

  • Oral Corticosteroids such as prednisone similar to hormones that the adrenal glands produce to fight stress associated with illnesses and injuries. They reduce inflammation and affect the immune system but can have several undesirable side effects such as increased blood pressure, weight gain, bone loss etc and so are reserved to cases not responding to other treatments.

  • Treating anaphylaxis: Severe allergic reactions (anaphylaxis) require treatment with a medicine called epinephrine, which can be life saving when given immediately.

Credits: The copyright to the image used above belongs to Fotosearch.com. All rights reserved


References

All information provided above is for basic awareness and education purposes only and should not be used for diagnosis or treatment of any medical condition under any circumstance. Please consult a licensed medical professional for these purposes. In case of medical emergency please call 911.

Copyright 2011 Talsk Research Inc. All rights reserved.
 
 
 
Privacy Policy | Disclaimer | Terms of Service Talsk Research, Inc. | Copyright © 2012 All Rights Reserved