Consult an allergist

March 2017

Allergies are very common and are easily self managed. However, where a persons life is debilitated, or allergic reactions are severe or life threatening further investigation by an allergy specialist is crucial.

Finding a diagnosis or the specific allergens can help a specialist individualise a treatment plan. A consultation usually compromises of a careful history, examination, skin patch testing which can be coupled with blood tests and provocation tests, to confirm the diagnosis.

History Taking


Getting a clear history from a patient is a fundamental stage of the first consultation.
  • The doctor can identify the allergic aspect of the symptoms
  • A first list of possible allergens can be set.
  • It must be rigorous and meticulous: it is often described as a police interrogation!
  • It helps finding out
    • The reasons for the consultation
    • The patient's allergy family history (parents, uncles, aunts, cousins...)
    • The patient's antecedents with other allergies, or other diseases
    • A specific description of the allergic symptoms: from the first onset of symptoms to present day.
    • Important details that are reviewed:
      • Criteria such as time, seasons, week days, week-ends... when the various symptoms occur.
      • When symptoms get better or worse
      • The role of holidays and week-ends which may for example point to a possible allergy at work.
      • The influence of climate and space
      • Allergic symptoms that occur indoors or outdoors.
      • Lifestyle, environment, pets and habits of the allergic person: Analysis of the home environment needs to be clear and precise. For example what type of pillows or duvets you have (feathers etc), if there are fitted carpets, wallpaper, damp in the bedroom and the nature of the heating system, the presence of animals, plants...
      • Professional or private travel, leisure, diet and dietary habits....
      • The effectiveness of anti allergic medication prescribed in the past are reviewed.

Skin prick tests




Skin prick tests are quick, cause very little pain. They are reliable giving a conclusion within 15 to 25 minutes, in most situations.
  • Reading the test: a positive allergic reaction causes a skin redness resembling the pimple of a mosquito bite accompanied by itchy skin.
  • The principle of the tests consists in reproducing on the skin an allergic reaction.
  • A drop of the suspected allergen is deposited on the skin; then at the centre of the drop, the allergy specialist makes a small skin prick with a sharp point.
  • A reaction resembling a mosquito bite testifies that the allergen tested may be responsible for certain symptoms.


This technique is well tolerated, even by very young children.

10 to 20% of positive skin prick tests do not necessarily mean that the tested person is allergic to the tested allergen.



These tests can be carried out on infants, contrary to the received opinion that skin prick tests cannot be carried out on young children. To wait for a child to be 5 or 6 years old before carrying out these tests delays the diagnosis, the beginning of a treatment and the symptoms may worsen. Current consensus specifies that these tests can be carried out very carefully, even before the child is 1 year old, especially in case of severe respiratory symptoms, episodes of urticaria or an oedema.


Patch tests

  • They are recommended when investigating the causes of eczema
  • Patch tests containing small quantities of suspected allergens are placed directly in contact with the skin on the patient's back and left there for 2 days.
  • Thanks to a reading grid, the results of the test can be interpreted by identifying each allergen.
  • A positive reaction means that the allergen tested is the one that may be responsible for a contact eczema.

Blood testing


If the skin prick tests are inconclusive, a blood test may be required.
  • The most frequent test is thetotal or specific Immunoglobulin E, the antibody intervening in allergic reactions to the suspected allergens.
  • This blood testing does not require fasting or to modify one's anti-allergic treatment.
  • Blood testing helps specialists obtain specific biological data for the allergy and to determine the allergen responsible for the symptoms.

Provocation tests


Oral, Nasal or Bronchial provocation tests are sometimes used when the diagnosis is difficult to establish.

Other examinations


A chest and sinuses x-ray proves sometimes useful.

In most cases, the patient discovers in one or two consultations the reason for his problems. But in certain cases, the investigation may take many months.

Where does one find an allergy specialist?


Unfortunately there is a shortage of specialist consultants in allergy and waiting lists on the NHS can be long. Always seek the advice and help of your GP in the first instance and if further investigation is required then your GP can refer you.

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