An allergen is a normally harmless substance that triggers the immune system to overreact in people with allergies. This response can cause allergy symptoms such as sniffling, sneezing and itchiness and watery eyes.
What are the entry sites of allergen?
Allergen enters mainly by inhalation, ingestion, injection and by direct skin contact.
What are the common allergens?
Common allergen responsible for most of the allergic reactions is