Allergies

ALLERGIES

Allergies occur when a person’s immune system reacts to substances (allergens) that are harmless for most people. When an individual with allergies comes into contact with an allergen, it enters the body, triggering an antibody response where the antibodies attach themselves to ‘Mast cells’. These cells then release chemicals, most importantly histamine, which mistakenly ‘attack’ the allergen, resulting in swelling and inflammation.

 

Anaphylaxis occurs when a person suffers a severe allergic reaction that is potentially life threatening. It is treated as a medical emergency and requires immediate treatment. It often involves more than one body system, for example, the skin, respiratory system, gastro-intestinal system, and heart may be affected at one time. The most common triggers of anaphylaxis are: food allergies, bites and stings, and medications. Anaphylaxis can cause facial swelling, swollen tongue, swollen throat, reddening of skin, difficulty breathing, hives, abdominal pain, vomiting, wheezing, unconsciousness, and drop in blood pressure. A dose of epinephrine (adrenaline) via injection is usually required, and people with severe allergies must carry around an EpiPen.

 

CAUSES:

  • Dust mites
  • Animal dander
  • Pollen
  • Mould
  • Dust
  • Fungal spores
  • Smoke
  • Air pollution
  • Weather
  • Food
  • Stress
  • Medicines
  • Chemicals (commonly latex, washing powders, or other household items)
  • Cosmetics (makeups and perfumes)
  • Insect venom (bee stings, ticks)
  • Atopy (inherited tendency to develop allergic diseases)
  • Lack of exposure to pets and germs as a child

 

SYMPTOMS:

Nose, sinuses, and throat (Common with hay fever):

  • Nasal congestion
  • Excess production of mucous
  • Itchy nose
  • Sneezing
  • Sinus pain
  • Headaches
  • Itchy and watery eyes
  • Itchy, sore throat
  • Snoring

Lungs and chest:

  • Asthma attacks
  • Swelling of lungs
  • Difficulty breathing
  • Coughing and wheezing

Stomach (caused by foods such as nuts, soy, seafood, dairy, and eggs):

  • Eczema
  • Colic
  • Bloating
  • Gas
  • Stomach upset
  • Vomiting and diarrhoea

Skin:

  • Eczema (red, scaly, itchy rash)
  • Urticaria (hives)

 

DIAGNOSIS:

  • Skin prick testing: Small amounts of allergens or their extracts are introduced to sites on the person’s skin which has been punctured with a small plastic or metal device. Sometimes the allergen is injected into the person’s skin with a needle or syringe. These injection sites are marked with pen or dye and monitored to see if an allergic reaction occurs. In the case of a reaction, visible inflammation will occur within 30 minutes, whether it’s a slight reddening of the skin, or a full-blown hive. The size and diameter of the hive/wheal are recorded to help determine the severity of the reaction.

(left: skin prick testing)

  • Patch testing: Adhesive patches treated with certain chemicals or allergens are put on the person’s skin (usually the back). This tests for delayed reactions and is used mainly for skin contact allergies. These patches are tested after 48 hours of application, and then again 2 days later
  • Blood testing: This test detects multiple allergens in a single sample. The concentration of specific IgE antibodies in the blood is measured, and it has been found that the higher the concentration of the antibodies, the greater likelihood of symptoms. These results help determine what the person is allergic to, and predict the disease development
  • Challenge testing: Small amounts of the allergen are introduced orally or through inhalation
  • Elimination/Challenge tests: The person completely avoids the suspected allergen to see if there is a lessening of symptoms. They may then be ‘challenged’ to reintroduce the allergen to see if the symptoms reoccur

 

TREATMENT:

  • Aeroallergen minimisation: This involves minimizing exposure to certain allergens, particularly those that are airborne
  • Antihistamines: These medications reduce the amount of histamine chemicals produced and therefore reduce the symptoms of hay fever. You can get antihistamine tablets, syrups, or even eye drops
  • Intranasal corticosteroid nasal sprays: These reduce inflammation and need to be used regularly as a preventative
  • Decongestant sprays: These are used to unblock the nose, and should only be used for a few days
  • Allergen immunotherapy (desensitization): This involves regularly exposing the person to increasingly larger doses of the allergen (extracts) via injection, or sublingual drops or tablets. This treatment is usually ongoing for 3-5 years
  • Epinephrine injections in the case of anaphylaxis

 

PREVENTION:

  • Limit pet interaction
  • Remove carpets
  • Minimize household humidity (minimize mould)
  • Use mite-proof pillow and mattress cases
  • Wash bedding frequently and replace pillows
  • Clean house regularly
  • Use air cleaners
  • Use cockroach traps if they are the problem
  • Avoid contact with triggers or allergens
  • Read food packaging carefully
  • Only have plants that require birds and insects to pollinate, not self-pollinating plants that give off seeds
  • Replace grass with fake grass or pavement
  • Keep windows closed during high pollen seasons
  • Hang washing indoors to avoid pollen sticking to them
  • Wear sunglasses outside to prevent eye irritation
  • Wash your hands after interacting with animals
  • Wear a medical alert bracelet if you are allergic to any medications
  • Carry an EpiPen
  • Regularly clean gutters, garbage bins, and refrigerator drip pans to reduce mould

 

REFERENCES:

https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/allergies

https://www.betterhealth.vic.gov.au/conditionsandtreatment/allergies

https://en.wikipedia.org/wiki/Allergy

https://www.allergyfacts.org.au/allergy-anaphylaxis/what-is-anaphylaxis

https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/anaphylaxis

http://acaai.org/allergies/types

http://www.ausee.org/allergies.htm

http://www.allergy.org.au/patients/about-allergy/what-is-allergy