Allergy is mechanism; asthma is a disease.

Allergy is an oversensitivity of the immune system to react to certain harmless things in our natural environment. These things (called allergens – what evokes or provokes allergy) could be pollens of weeds or trees, house dust, fungal spores, food items, drugs or cosmetics.

The important thing to remember is that these items do not cause any adverse reaction to most normal or non-allergenic people. However, to people with an allergic tendency with sensitization to that particular allergen, they will cause a reaction.

The reaction may occur in different parts of the body:

• Skin : urticaria, allergic dermatitis, contact dermatitis
• Nose : allergic rhinitis
• Intestines : vomiting and diarrhea following food
• Lungs reaction : Asthma

Allergic reaction occurring in the lungs (or more specifically in the air tubes) causing inflammation and narrowing of the airways is called asthma.

So allergy is a broader term and includes many diseases including asthma.

Many a times patients ask the doctor: “Doctor I hope this is not Asthma; I think it is Allergy”

Inherently the patient does not like the word “Asthma”. The word asthma evokes certain notions in his mind which are not pleasant. He/she would much rather like the term allergy.

Also, not all of asthma is caused by allergy. In children 80% of asthma is caused by allergic factors. Only 50% or so of asthma in adults is caused by allergy. Further more, in a given patient both allergic reasons (pollen season or too much exposure to dust) and non-allergic reasons (viral infections or emotions) could cause aggravation of asthma symptoms.