Different types of allergic reactions

Hypersensitivity reactions are conditions in which an immune response results in exaggerated or inappropriate reactions that are harmful to the host. It usually occurs after the 2nd contact with an allergen. The 1st contact is a necessary preliminary event that induces sensitization to that particular allergen.


There are four types of hypersensitivity reactions, these are:

• Type 1: Immediate Hypersensitivity (Anaphylactic)

o Manifests itself in tissue reactions occurring with in minutes after the antigen combines with the matching antibody; it may take place as a systemic anaphylaxis or as a local reactions
o First contact with an antigen- Ige formation- IgE binds to basophils and mast cells (complex). 2nd contact with the same antigen-complex will release histamines –vasodilatation
o Increase capillary permeability
o Smooth muscle contraction examples are skin allergy; hay fever and asthma.

• Type II: Hypersensitivity (Antigen-Antibody Reaction)

o It involves the binding of antibodies (IgG or IgM) to cell surface antigen; activates the compliment system to destroy or damage the cells; Example: hemolytic anemia; ABO incompatibility; RH incompatibility; Goodpasture’s Syndrome: Myasthenia Gravis

• Type III. Hypersensitivity (Immune Complex)

o When antibodies combine with specific antigen, immune complexes are formed which may cause several disorder. These immune complexes are deposited in several tissues or organs (joints, skin, kidneys, and blood vessels) Example: serum sickness: Glomerulonephritis

• Type IV: Cell-meditated Hypersensitivity (Delayed type)

o It is a responsibility of specifically sensitized T lymphocytes. Occurs hours or days after contact with the antigen and often lasts for days. When antigen enters the skin, cell-meditated hypersensitivity is induced within 24- 48 hours. Vesicle formation, itching, necrosis of the skin, erythema and eczema. Examples are: tuberculosis, contact dermatitis and poison ivy.

Here are the different kind of allergic reaction include:

Hay Fever (allergic rhinitis)

Hive (Urticaria)

Poison Ivy and plant allergies

Bee sting allergy

Pet allergies

Latex allergy

Mold Allergy

Cosmetic Allergies and drug allergies

Eczema (Atopic dermatitis)

Eye allergies (allergic conjunctivitis)

For food allergies such as:

Milk allergy

Egg allergy

Nut allergy

Fish allergy

Shellfish allergy

Soy allergy

Sun allergy

Wheat allergy

Aspirin allergy (Salicylate Allergy)

Fall allergies

Allergies can be defined as an overreaction of the immune system to antigens such as bee stings, food, insect stings or pollen which could trigger an allergy.

Seasonal allergic rhinitis is a one type of allergic reaction which responses to pollen and other microscopic substances which exist at certain times of the year. Another type of allergic reaction is allergy to insect stings.

The second sting triggers the allergic reaction compared to the first sting that produces a normal sting reaction. Another type of allergic reaction is allergy to latex and main sources of these reactions are the use of rubber gloves, condom and medical devises which trigger reaction.

Mold allergy can be obtained through seasonal changes in weather or can be found in cosmetics, fragrances and food preservatives. Some individuals are allergic to pets through their furs or feathers which trigger the reaction. The invisible flakes coming from animal skin known as dander triggers sneezing, watery eyes and stuffy nose.