Allergy causes?

The real cause of why allergy develops remains unknown still. But these are some of the factors associated with allergic disease development:

  1. Genetics: allergy is more common if one or both of the parents had them.
  2. Allergen type: some allergens are heat resistant or stomach acid resistant.
  3. Route of entry into body: if an allergen enters the body through the nose or skin in its undigested form it has a higher chance of causing allergy.
  4. Breast feeding: generally reduce the chance of eczema and wheezing.
  5. Early feeding: contrary to old belief, starting feeding early between 4 to 6 months of age is actually protective!  The recent evidence is that early feeding and giving the allergenic food types early may prevent the development of food allergy.
  6. Viruses: more respiratory viruses in childhood means a higher the chance of developing asthma in children.
  7. Antibiotics: more antibiotics in childhood or during cesarean section is associated with higher risk of asthma. 
  8. Paracetamol: according to the GINA asthma guidelines paracetamol, a medicine used to reduce temperature, was associated with higher chance of asthma.
  9. Pollution: its noted that living in a polluted area has  a higher risk of asthma and rhinitis. 


Allergens are either proteins or large chemical structures. They are large in the sense of their molecular weight but in fact are so small they can not be seen with the eyes! The have the ability to stimulate the immune response strong enough to cause a reaction and develop an immune memory. Which means when the allergen enters the body again it would remember it! With some allergens the immune systems develops with time and they stop reacting to them. Allergens enter the body through the nose, lungs, skin, digestive system and veins. Skin in these areas is the first line of defense. Hence its important to treat allergy inflamed skin.

Examples of allergens:

  1. Inhaled: the allergen enters through the nose and breathing. They cause symptoms in allergic rhinitis, conjunctivitis, sinusitis and asthma. examples include dust mites, pollen (grass/trees) , animals (cats, dogs, birds), fungal spores & insects (e.g cockroaches).
  2. Food: food enters the body through eating but also through the skin and inhalation. The reaction can be mild or life threatening like in anaphylaxis. Any food can cause allergy but nine food items make the majority of reactions. These include: cow milk, egg, soy, wheat, peanut, sesame, fish, shellfish, & nuts.
  3. Insect venom: such as bee venom and ants. 
  4. Drugs: such as antibiotics (penicillins, cephalosporins). 
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