DETAILS OF HYPERSENSITIVE REACTIONS INCLUDING SYMPTOMS, ETIOLOGY, DIAGNOSIS, COMPLICATIONS & RISK FACTORS, TYPES OF THE ALLERGIC REACTIONS ETC.

1. HYPERSENSITIVITY
OR ALLERGIC
REACTIONS
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2. Mr. Shaktiprasad Pradhan
M.Pharm, Ph.D*
Research Professional, UDPS
shakti.pharma16@gmail.com
Utkal University, Bhubaneswar
Odisha, India
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3. INTRODUCTION
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4. INTRODUCTION
In day to day life certain metal jewellery or
certain cosmetics brings the hypersensitivity causing
skin rashes in some people, while some others sneeze
uncontrollably on exposure to dusts or pollens.
Hypersensitivity or allergic reactions are
overstated sensitivities that occur when the immune
system responds unusually to foreign substances
such as pollen, dust, bee venom or pet dander, certain
foods and drugs.
Such kind of foreign substances are called
allergens, which can cause reactions upon skin
contact or when they are breathed, swallowed or
injected.
These things ultimately trigger the immune system
causing inflame of the skin, sinuses, airways,
digestive system etc.
(Cont.) 4

5. .
HYPERSENSITIVE REACTION
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6. .
HYPERSENSITIVE REACTION
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7. .
HYPERSENSITIVE REACTIONS
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8. .
Hypersensitivity reactions are quite common and
may occur seconds to hours after get in touch with
the allergens, however some hypersensitivity
reactions take more than a day or 24 hrs to appear.
Although a number of hypersensitivity reactions
are mild, some may be harmful or life-threatening as
they may have impacts locally, involving a small
part of the body or may have impact on the whole
body.
The severeness of hypersensitivity reactions varies
from person to person and can range from little
irritation to anaphylaxis (a potentially life-
threatening emergency).
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9. SIGNS & SYMPTOMS OF
HYPERSENSITIVITY
REACTION
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10. SIGNS & SYMPTOMS
The signs & symptoms of a hypersensitive reaction
can vary from mild to severe.
The first time exposure to an allergen may bring
some mild symptoms but the signs & symptoms may
be severe in repeatedly exposure with the allergen.
Rarely, some severe and sudden hypersensitivity
reactions develop within seconds after exposure to an
allergen & without right treatment a severe allergic
condition can result in fatality within 15 minutes.
Specifically the foods & insect stings bring some
types of allergies, can trigger a severe hypersensitivity
reaction known as anaphylaxis, a life-threatening
medical emergency & can cause to go into shock.
(Cont.)
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11. Anaphylaxis includes common signs and
symptoms like:
Loss of consciousness
A drop in blood pressure
Severe shortness of breath
Skin rash
Light-headedness
A rapid, weak pulse
Nausea and vomiting
Various signs & symptoms of the hypersensitivity
reaction may depend on the allergens involved & can
affect the airways, sinuses and nasal passages, skin,
digestive system etc. (Cont.)
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12. .
HYPERSENSITIVE REACTION & SYMPTOMS
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13. Signs & symptoms of mild allergic reactions can
cause:
Hives (itchy red spots on the skin)
Itching
Nasal congestion (known as rhinitis)
Rash
Scratchy throat
Watery or itchy eyes
Signs & symptoms of severe allergic reactions are
different & due to various factors like food
allergy which can cause:
Tingling in the mouth
Swelling of the lips, tongue, face or throat
Hives
Anaphylaxis (Cont.)
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14. Insect sting allergy can cause:
A large area of swelling (Edema) at the sting site
Itching or hives all over the body
Cough, chest tightness, wheezing or shortness of
breath
Anaphylaxis
Drug allergy can cause:
Hives
Itchy skin
Rash
Facial swelling
Wheezing
Anaphylaxis
(Cont.) 14

15. Hay fever or allergic rhinitis can cause:
Sneezing
Itching of the nose, eyes or roof of the mouth
Runny, stuffy nose
Watery, red or swollen eyes (Conjunctivitis)
Atopic dermatitis (Skin Eczema) can cause:
Itch
Redden
Flake or peel
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16. CAUSES/ ETIOLOGY OF
HYPERSENSITIVITY
REACTION
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17. CAUSES/ ETIOLOGY
Hypersensitivity or allergic reactions start when
various types of allergens trigger the immune
system for making antibodies, a type of protein
specifically the IgE or immunoglobulin E antibodies.
This succeeds to an antigen-antibody reaction as
the IgE antibodies bind with the allergen molecules
leading to the release of histamine.
These histamines ground for the various
inflammatory allergic symptoms of the
hypersensitivity reaction such
as rashes, itching, sneezing etc.
The hypersensitivity reactions appear to run in
families and can be inherited. (Cont.)
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18. People who have the hypersensitivity are typically
allergic to one or more number of allergens.
Commonly allergens include:
Airborne allergens: Pollens, animal dander, dust mites,
molds.
Certain foods: Mostly peanuts, tree nuts, wheat, soy,
fish, shellfish, eggs, milk, mushroom.
Insect stings: From a bee or wasp bite.
Medications: Mainly Penicillin or Penicillin-based
antibiotics, Aspirin.
Metals: Nickel (Most frequent allergen), Cobalt,
Copper, Chromium.
Plants or plant parts: Ragweed, Pigweed, Sunflower,
Tumbleweed, Sagebrush, Oak, Birch, Cedar, Plant latex.
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19. HYPERSENSITIVITY & ALLERGENS
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20. COMPLICATIONS & RISK
FACTORS OF
HYPERSENSITIVITY
REACTION
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21. COMPLICATIONS & RISK FACTORS
The hypersensitivity reactions might be more
likely to develop an allergic condition if one:
Have a family history of allergies, such as hay
fever, hives or eczema.
Is a child.
Have asthma or another allergic condition.
Having an allergy can increase the risk of other
medical problems, which can be either mild or severe
including:
If one has severe allergies, then there is an
increased risk of anaphylaxis. Foods, medications
and insect stings are the most common that triggers
of anaphylaxis. 21

22. If one has an allergy, asthma may be more likely
to occur affecting the airways and breathing. In
many cases, asthma is triggered by exposure to an
allergen in the environment which is allergy-
induced asthma.
Having asthma or hay fever, there is an
increased risk of getting sinusitis and infections of
the ears or lungs.
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23. DIAGNOSIS OF
HYPERSENSITIVITY
REACTION
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24. DIAGNOSIS
The diagnoses for hypersensitive reactions mostly
done clinically are skin tests, challenge or
elimination type tests & blood tests.
I. Skin tests
Skin tests are most valuable for diagnosing:
•Food allergy (shellfish or peanuts)
•Mold, pollen, and animal dander allergy
•Penicillin allergy
•Venom allergy (mosquito bites or bee stings)
•Allergic contact dermatitis (rash after touching allergens)
A skin test involves applying a small amount of a
suspected allergen to the skin and observing for a
reaction. (Cont.) 24

25. The substance may be taped to the skin (patch test),
applied via a small prick to the skin (skin prick test),
or injected just under the skin (intradermal test).
II. Challenge (elimination-type) tests
Challenge testing is useful in diagnosing food
allergies.
It involves removing a food from the diet for several
weeks and watching for the symptoms when the food
again eaten.
III. Blood tests
Blood tests are an option when skin testing isn’t
helpful or possible.
Blood tests for an allergy reaction confirm the blood
for antibodies against a possible allergen.
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26. TYPES OF
HYPERSENSITIVITY
REACTIONS
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27. TYPES
The allergens & other foreign substances can trigger
the host four types of hypersensitivity reactions such
as Type I, II, III & IV.
As the Type I, II & III allergic reactions occur within
24 hrs of exposure to the allergens, they are called the
immediate allergic reactions.
Type IV reactions typically occur after 24 hrs of
exposure to the allergens and are called the delayed
allergic reactions.
I. Type I/ Immediate Hypersensitivity/ Anaphylactic
Reaction
Type I hypersensitive reactions are systemic or
localized & mediated by IgE antibodies, of the mast
cell or basophil. (Cont.) 27

28. IgE antibodies are produced in response to
allergens like pollen, animal dander or dust mites,
certain foods etc. & cause the release of histamine
causing inflammation and swelling.
During the anaphylactic reaction histamine,
serotonin, bradykinin and lipid mediators such as
platelet activating factor, prostaglandins and
leukotrienes are released having the tissue
damaging potential.
Bronchial asthma, Allergic rhinitis,
Allergic dermatitis, Food allergies, Allergic
conjunctivitis (Eye inflammation),
Anaphylaxis (Allergic shock) are some very common
examples of Type I hypersensitive reactions. (Cont.)
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29. II. Type II/ Cytotoxic Reaction/ Antibody-dependent
The Type II hypersensitive reactions are mediated
by IgG & IgM antibodies.
These antibodies react directly with the antigens
that bound to the cell membrane to induce cell lysis
by activating the complement system, a component
of immunity.
These antigens may be intrinsic or self as in
autoimmune reactions or extrinsic or non-self.
Conditions like Rh incompatibility of a newborn,
blood transfusion reactions and autoimmune
diseases.
(Cont.)
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30. The autoimmune diseases which are Type II
hypersensitive reactions include the
Autoimmune neutropenia, Pemphigus Vulgaris,
Immune thrombocytopenia, Bullous Pemphigoid,
Autoimmune hemolytic anemia, Goodpasture's
syndrome.
III. Type III/ Immune Complex Reactions
Type III hypersensitive reactions are also mediated
by the IgG and IgM antibodies, forming antigen-
antibody immune complexes.
These immune complexes activate complement
system, which results in PMN chemotaxis and
activation.
Then the PMNs release tissue damaging enzymes.
(Cont.)
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31. Commonly the Type III hypersensitive reactions are
observed in Serum sickness, Arthus reaction,
autoimmune diseases like systemic lupus
erythematosus also in chronic infectious diseases like
leprosy.
IV. Type IV/ Cell-Mediated/ Delayed Hypersensitivity
Type IV hypersensitive reactions are also called the
delayed type of hypersensitivity or allergic reactions as
they occur after at least 24 hrs of exposure to the
allergens & usually take 48-72 hrs or longer, to fully
develop.
These type of hypersensitivities are initiated by the
T-lymphocytes and mediated by the T-cells &
macrophages, which makes a response involving the
interaction of antigens with the surface of
lymphocytes. (Cont.)
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32. Chronic infectious diseases, such as tuberculosis,
fungal infections exhibit Type IV hypersensitivity
along with certain metal sensitive skin allergies.
The hypersensitivity reactions, mainly Type III &
IV may be involved in the pathogenesis of
Periodontitis (serious gum infection damaging gums
& also jawbone).
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33. .
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34. REFERENCES
https://dermnetnz.org/topics/allergies-explained/
https://www.ncbi.nlm.nih.gov/books/NBK513315/
https://www.healthline.com/health/allergies/allergic-
reaction
https://en.wikipedia.org/wiki/Hypersensitivity
https://teachmephysiology.com/immune-
system/immune-responses/hypersensitivity-reactions/
https://www.immunopaedia.org.za/immunology/archive/
type-i-iv-hypersensitivity-reactions/immune-complex-
formation/hypersensitivity-reactions/
https://healthengine.com.au/info/hypersensitivity-
reaction-type-i
https://www.sciencedirect.com/topics/immunology-and-
microbiology/type-i-hypersensitivity. 34

35. Thank You
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