An allergy is a hypersensitive disorder of immune system.

An allergy is a hypersensitive disorder of immune system.

An allergy is a type of reaction of the immune system. Substances that often cause allergic reactions are pollen, dust mites, mold spores, pet dander, food, insect stings and medicines.

The body's defense mechanism works over time to react against these foreign particles (known as allergens), which may pose danger to normal functioning of the human system. People with allergies have an exaggerated response of the immune system. However, in most allergic reactions, it is responding to a false alarm.

Allergies can cause a running nose, sneezing, coughing, itching, skin rashes or asthma. Symptoms vary from person to person and with the type of allergen. Rarely, allergies can set in a severe reaction called anaphylaxis, which is life-threatening.

Allergies can develop at any age and the risk of developing allergies is often related to the presence of allergies in the parents.

Together with the help of physical examination, history and allergy testing, the doctor can diagnose the cause of allergy and design treatments that will help the patient feel better.

Avoiding the allergen or minimizing the exposure is the most effective preventive measure against allergies. Antihistamines, glucocorticoids, anti-cholinergic drugs and decongestants help to alleviate the symptoms of allergy. Adrenaline is used to treat severe allergic reactions called anaphylactic reactions.

Immunotherapy can either reduce the severity or eliminate hypersensitivity reactions. This is done by vaccinating the person with progressively larger doses of the allergen in question.
For this general concept of the changed capacity for reaction, I propose the term "allergy". "Allo" denotes the deviation from the original state, from the behavior of the normal, as in "allorhythmia","allotropy".