Allergies

It is a condition in which there is an increased immunological response by the body to a substance.There is a wide spectrum of manifestation of symptoms ranging from simple itching to life threatening anaphylaxis.
Manifestations may be itching,urticaria,eosinophilia,angioedema,anaphylaxis..These reactions are mediated through IgE mediated. For it to occur the body must have been initially sensitised with particular allergen.It is an hypersensitivity reaction.
Types of Hypersensitivity :

1. Type I-immediate hypersensitivity
2. Type II-Antibody mediated
3. Type III-Immune complex mediated
4. Type IV- T-cell mediate

It comes under type I hypersensitivity.It is mediated by IgE  secreted by B-cell, IgE binds to the mast cells causing the release of mediators for the reaction on exposure to the same antigen again.This whole process occurs within minutes,hence the name.

Mediators:

• Histamines
• Leukotrienes
• PAF
• Prostaglandins

Management:

• The main stay of management is the complete avoidance of the stimuli.
• Desensitisation of the allergen with serial exposure of the patient with varied subclinical concentrations of the antigen.
• Most of the cases respond well to symptomatic management with anti histaminics and time
• Active management is  life saving in cases of angioedema and anaphylaxis.In these cases epinephrine is the life saving drug, along with intravenous fluids.