|Allergy is an immune system disorder, medication and infection, arises when the immune system responds to an allergen. The harshness of allergies differs from person to person and from negligible irritation to life threatening anaphylaxis. It causes red eyes, itching, runny nose, hives, eczema and asthma attack. General treatment of allergy is to avoid allergens and medication; in severe cases few medicines can decrease symptoms as antihistamines and decongestants. The impact factor of journal provides quantitative assessment tool for grading, evaluating, sorting and comparing journals of similar kind. It reflects the average number of citations to recent articles published in science and social science journals in a particular year or period, and is frequently used as a proxy for the relative importance of a journal within its field. It is first devised by Eugene Garfield, the founder of the Institute for Scientific Information. The impact factor of a journal is evaluated by dividing the number of current year citations to the source items published in that journal during the previous two years.