Introduction to Allergies



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Chapter 1 : Introduction to Allergies



Allergy arrow_upward


  • An allergy is a hypersensitivity disorder of the immune system.
  • Allergic reactions occur when a person's immune system reacts to normally harmless substances in the environment .
  • A substance that causes a reaction is called an allergen. These reactions are acquired, predictable, and rapid.
  • Allergy is one of four forms of hypersensitivity and is formally called type I (or immediate) hypersensitivity.
  • Allergic reactions are distinctive because of excessive activation of certain white blood cells called mast cells and basophils by a type of antibody called Immunoglobulin E (IgE).
  • This reaction results in an inflammatory response which can range from uncomfortable to dangerous.

  • Symptoms arrow_upward


  • Allergy symptoms depend on your particular allergy, and can involve the airways, sinuses and nasal passages, skin, and digestive system.
  • In some severe cases, allergies can trigger a life-threatening reaction in your body known as anaphylaxis.

  • Hay fever

  • Hay fever, also called allergic rhinitis, may cause:
    • Congestion
    • Itchy, runny nose
    • Itchy, watery or swollen eyes (conjunctivitis)

    Atopic dermatitis

  • Atopic dermatitis, an allergic skin condition also called eczema, may cause:
    • Itchy skin
    • Red skin
    • Flaking or peeling skin

    Food allergy

  • A food allergy may cause:
    • Tingling mouth
    • Swelling of the lips, tongue, face or throat    
    • Hives
    • Anaphylaxis

    Insect sting allergy

  • An insect sting allergy may cause:
    • A large area of swelling (edema) at the sting site.
    • Itching or hives all over your body.
    • Cough, chest tightness, wheezing or shortness of breath.
    • Anaphylaxis.

    Drug allergy

  • A drug allergy may cause:
    • Hives
    • Itchy skin
    • Rash
    • Facial swelling
    • Wheezing
    • Anaphylaxis
  • Some types of allergies, including allergies to foods and insect stings, have the potential to trigger a severe reaction known as anaphylaxis.
    • A life-threatening medical emergency, this reaction can cause you to go into shock.
  • Signs and symptoms of anaphylaxis include:
    • Loss of consciousness
    • Lightheadedness
    • Severe shortness of breath
    • A rapid, weak pulse
    • Skin rash
    • Nausea and vomiting
    • Swelling airways, which can block breathing

    Causes arrow_upward


  • An allergy starts when the immune system mistakens a normally harmless substance for a dangerous invader. The immune system then produces antibodies that are always on the alert for that particular allergen.
  • When you're exposed to the allergen again in the future, these antibodies can release a number of immune system chemicals, such as histamine, that cause allergy symptoms.
  • Common allergy triggers include:
    • Airborne allergens, such as pollen, animal dander, dust mites and mold.
    • Certain foods, particularly peanuts, tree nuts, wheat, soy, fish, shellfish, eggs and milk.
    • Insect stings, such as bee stings or wasp stings.
    • Medications, particularly penicillin or penicillin-based antibiotics.
    • Latex or other substances you touch, which can cause allergic skin reactions.

    Risk factors arrow_upward


  • You may be at increased risk of developing an allergy if you:
    • Have asthma or a family history of asthma or allergies: You're at increased risk of allergies if you have family members with asthma or allergies such as hay fever, hives or eczema.
    • Are a child: Although you can become allergic to something at any age, children are more likely to develop an allergy than are adults. Children sometimes outgrow allergic conditions as they get older.
  • Having an allergy increases your risk of certain other medical problems, including:
    • Anaphylaxis
    • Another allergy
    • Asthma
    • Atopic dermatitis (eczema), sinusitis, and infections of the ears or lungs
    • Fungal complications of your sinuses or your lungs.

    Treatments and Drugs arrow_upward


  • Allergy treatments include:
    • Allergen avoidance: Your doctor will help you take steps to identify and avoid your allergy triggers. This is generally the most important step in preventing allergic reactions and reducing symptoms.
    • Medications to reduce symptoms: Allergy medications can help reduce your immune system reaction and ease symptoms. The drugs you use depend on the type of allergy you have.
    • Immunotherapy: For severe allergies or allergies not completely relieved by other treatment, your doctor may recommend allergy shots (immunotherapy).
    • Emergency epinephrine: If you have a severe allergy, your doctor may give you an emergency epinephrine shot that can reduce symptoms until you get emergency treatment.

    Lifestyle and Home Remedies arrow_upward


  • Some allergy symptoms improve with home treatment.

  • Household airborne allergy symptoms

  • Symptoms such as those caused by dust mites or pet dander, may improve by taking steps to reduce your exposure to allergens. Steps include:
    • Frequently washing bedding and stuffed toys in hot water
    • Maintaining low humidity
    • Regularly using a vacuum with a fine filter such as a high-efficiency particulate air (HEPA) filter
    • Replacing carpeting with hard flooring.



    Mold allergy symptoms

  • These may be alleviated by reducing moisture in damp areas, such as your bath and kitchen, by using ventilation fans and dehumidifiers, and fixing any leaks inside and outside of your home.

  • Alternative medicine

  • The following herbs may be of some benefit in treating allergies:
    • Butterbur may help relieve symptoms of allergic rhinitis.
    • Milk thistle may improve symptoms of allergic rhinitis.
    • Phleum pratense may help relieve symptoms associated with asthma.
  • If you're interested in adding alternative therapies to your treatment plan, always talk with your doctor first.

  • Prevention arrow_upward


  • Preventing allergic reactions depends on the type of allergy you have. General measures include the following:
    • Avoid known triggers: Even if you get treatment for your allergy symptoms, you still need to try and avoid your triggers. Some allergic reactions are triggered or worsened by temperature extremes or emotional stress.
    • Wear a medical alert bracelet: If you've ever had a severe allergic reaction. A medical alert bracelet (or necklace) lets others know that you have a serious allergy in case you have a reaction and you're unable to communicate.


    Thank You from Kimavi arrow_upward


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