Allergy is an acquired altered body response of a person to normally harmless substance which usually does not affect most people in their daily life.
Any foreign substance that provokes reaction in the body is called an allergen.
Drugs used to treat blood pressure (beta blockers) like Tenormin and Aspirin, NSAIDs (pain relieving drugs) produce cough, wheeze and asthma like symptoms in sensitive individuals.
The common ones are:
House dust mite present in the dust of carpets, old books, furniture, boxes, blankets, mattress and stuffed toys. Presence of the body parts and excreta of cockroaches where cleanliness is lacking and ample garbage is left uncovered which also serve as a food factor for these insects. Indoor mold or fungal growth in dark damp places, basements, toilets, leaking pipe area & wall papers which collect humidity thus helping in the proliferation of molds as well as dust mite.
Dander of cat dog etc.
Beside allergens, other factors that increase allergy in susceptible persons are preservatives, pollutants or irritants i.e. food preservatives, coloring agents and preservatives in cosmetics etc. cigarette or automobile smoke, cold air, perfumes, air fresheners, chemical sprays, fumes of gases like nitrogen dioxide, Sulphur dioxide, carbon monoxide released from vehicles, industries, gas stoves or from burning of fuel like wood, dung etc. used in homes for cooking /heating purpose, vapors of varnish, paints, polish etc. can also cause allergy.
If you get a cold symptom which is a viral infection, then you will suffer from mild fever, sore throat, some sneezing, thick mucous in nose, nasal obstruction aches and pains etc. But if the symptoms are due to allergy than you will get itching in eyes, nose, intense sneezing, watery discharge from the nose, dry irritating cough and no fever.
when some allergy producing particles enters the nose and comes in contact with the internal lining of the nose than as a reaction there is swelling and inflammation in the nose and the patient suffers from symptoms like sneezing, nasal itching, watery nasal dripping, watering of eyes and mild sore throat etc.
Hay fever is also called seasonal allergic rhinitis because it often occurs in a specific season. It is mostly seen in spring season when pollen count is high in the air or in early summers when harvesting is done and there is a lot of thresher dust in the air.
This is called perennial allergic rhinitis and it is mostly due to house dust mite, indoor molds or animal dander?