An allergy can be defined as an unwanted bodily response to a substance or organism. Allergies are caused by a complex combination of influences. Allergy or hypersensitivity is an abnormal reaction to protein substances that occur naturally. If an allergic person is exposed to these substances called allergens the body's immune system gets ready to fight them. White blood cells produce an antidote (antibody) against the allergen. The antibody sticks to the surface of the allergy cells. This process is called sensitisation and the body will be ready to tackle the allergen next time it is exposed to it.
After this change there is an allergic reaction every time the body is exposed to the allergen. The allergen sticks to the antibodies on the surface of the allergy cells. This coupling causes the granula (little stores in the allergy cells) to release histamine which causes the symptoms of allergy.
Allergens are microscopic protein substances that are common and provoke allergic people to produce antidotes (antibodies). The most common allergy provoking substances are pollen from weeds grass flowers and trees; mould and mould fungus; house dust mites; fur from cats and dogs; medicines.
The predisposition to hypersensitivity is hereditary. If one or both parents or close family members suffer from hypersensitivity it is advisable to talk to a doctor about how to lower the risk of the children developing it.
There are many tests to diagnose an allergy but the most common types include blood tests which look for elevated white blood cell counts or a reaction when an allergen is exposed to the patient. Blood tests are not 100% reliable and other tests can be used including the scratch test which involves starching the skin of the arm or back and dropping a liquid allergen onto that area to see if there is a reaction. A positive reaction is reliable but a negative reaction may not be as you maybe allaeric but there was no reaction.
For food allergies the only test is to go on an elimination diet whereby each week a new food item is added to find which product causes the reaction. This process is long but is the only way.
Treatment of allergies can take many forms as there are a number of different types of alleriges each with their own cause. The two most common over-the-counter (OTC) medications for treating allergies are antihistamines and decongestants.
Antihistamines help relieve sneezing itching and runny nose. They work best if you take them routinely during the allergy season rather than waiting until you feel miserable. Decongestants come as topical eye and nose drops and sprays and as oral tablets and liquid. They narrow blood vessels and reduce blood flow in the affected area which helps clear congestion and improve breathing.