Allergy overview and Definition

Allergy is an exaggerated response of the body’s immune system to the foreign antigen.They compromise a range of disorders from mild to life threatening and affect many organs.          


Allergic reactions accounts for 20-30% of the medical emergencies

Clinical signs & symptoms

  • Difficulty breathing, cough.
  • Generalized (widespread) hives that appear as a red, itchy rash that spreads to areas other than the area that was stung.
  • Swelling of your face, throat or mouth tissue.
  • Wheezing or difficulty swallowing.
  • Restlessness and anxiety.
  • Rapid pulse.
  • Dizziness or a sharp drop in your blood pressure.

Differential Diagnosis



           Several markings are made on the patient skin and each mark should be 2 cm apart.

         Allergic solution is taken.

          A drop is placed on the skin and the prick is made with the lancet and the reactions happens within 15-20 mints and the results are checked and graded accordingly.

 Intradermal skin test

It is similar to skin test in which the the small amount of allergen is injected into the skin.This test is done if the prick test is negative.

Challenge test

This test is done in food allergy cases.The patient is asked to consume small amount of the allergen and the effects are supervised under healthcare proffesional

Blood test

In this test, a sample of your blood is drawn. This test is also called serum IgE testing or ImmunoCAP test.InnumoCAP test is based in the fluoro Immunoassay and complement system.It is used to measure the amount of antibodies produced in response.

Patch test

This test involves placing a small amount of possible allergens on your skin (usually your back) and then covering each of them with a bandage. Your allergist may perform this test if they suspect an allergy in which the allergic reaction is delayed. The bandages are left in place for two to three days before you return to the office to have the bandages removed and your skin examined.

Component-Resolved Diagnostic Tests or Molecular-Based Diagnosis:s

        This test is done in food allergy patients to patients to obtain what type of proteins they are allergic to it.

Mast cell Tryptase Levels Assessment:

      The serum level of  β-tryptase  can be used to assess anaphylaxis and mast cell activation.


stay away from the allergens and follow the precautionary measures.


Davidson princple and manual of general medicine-22nd edition

Harshmohan Pathology -4 th edition