Allergies – Causes and Symptoms


Our immune system performs a very important function of defending our body from foreign invaders such as bacteria and viruses that can harm us and make us sick. But sometimes the immune system inappropriately reacts to certain substances which in most cases are usually harmless; this reaction is known as allergy. Substances that trigger an allergy are called allergens and can be found in any food, drink or in the environment. Eggs, pollens, milk are some very common examples of allergens. Allergies can affect the nose, eyes, skin, sinuses, throat, stomach and lungs.

Allergy Causes

The immune system releases antibodies to protect you from illness. The antibodies are proteins that deliver a message to cells to stop that foreign substance that makes us sick. For allergies, the immune system generates Immunoglobulin, also known as IgE, to pass on the information that a chemical defense against a foreign substance is needed.

With time the immune system develops an immunological memory, which enables the body to respond more quickly to any allergen by releasing a number of immune system chemicals such as histamine that causes allergic reactions. An allergy response is produced due to this which may include sneezing, coughing, wheezing and rashes.

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Family history is one of the major factors that increase the chance to develop allergies. If any of the parents is allergic, there is a 30-50% chance that their child may develop the same allergy.

The most common Allergens that can trigger an allergy reaction are:

  • Airborne allergens such as grass and tree pollen, dust mites, mold, and animal dander.
  • Food allergies: Certain foods such as peanuts, soy, fish, milk, shellfish, wheat, eggs, and tree nuts can cause allergy.
  • Medications: Some medications like aspirin and antibiotics particularly penicillin or penicillin-based antibiotics can cause allergic reactions.
  • Insect stings or insect bites such as from a bee or a wasp can trigger an allergy.
  • Latex or other materials can lead to skin allergy when touched.

Allergy causesAllergy Symptoms

Allergy symptoms, depending upon the allergen involved can affect your nasal passages, digestive system, respiratory system, sinuses, and skin. An allergic reaction can be mild or severe. Some severe allergic reaction known as anaphylaxis can be life-threatening as well.

A food allergy causes:

  • Hives or skin rashes
  • Anaphylaxis
  • Swelling of the lips, tongue or throat
  • Vomiting, diarrhoea or tummy pain
  • Bloating

Allergic rhinitis or Hay fever causes:

  • Sneezing
  • Runny or stuffy nose
  • Conjunctivitis
  • Itching eyes, nose or roof of the mouth

An insect sting allergy causes:

  • Itching or swelling at the sting site
  • Hives and itching all over the body
  • Cough, wheezing and chest tightness
  • Anaphylaxis

A drug allergy causes:

  • Itching
  • Hives
  • Rashes
  • Swollen face
  • Wheezing
  • Anaphylaxis

Allergy symptomsAnaphylaxis

Some allergies to foods and insect stings can cause a severe reaction known as anaphylaxis. This can be life-threatening and can cause you to go into shock. Symptoms of anaphylaxis are:

  • Skin Rashes
  • Loss of consciousness
  • Breathlessness
  • Drop in blood pressure
  • Light headedness
  • Nausea and vomiting

Read more about Allergies- Checkup and Treatment