An allergy can be defined as an abnormal reaction or overreaction of the immune system of the human body that arises or occurs due to any harmless or harmful substance. The substances that are responsible for allergic reaction are called as allergens.

The potential allergens may be anything and these potential allergens may include food, pollen, microorganisms, and antibiotics. Allergy may not be limited to a particular substance and it differs from an individual to an individual. A large variety of potential allergens may be responsible for causing allergies and the list includes-

  1. Pollens, foods, insects venoms, molds, animal proteins, foreign serum proteins,
  2. Drugs, industrial chemicals.

Causes of Allergies

The causes of allergy are not limited to a specific factor but may be triggered by an allergic reaction. In majority of cases, people know beforehand, the causes of allergic reaction and the particular allergen that triggers allergic reaction in them. The allergic reaction is quite unique for each individual and also the reaction time of allergens may vary widely. Some people will have allergic reaction immediately while the others will take some time to develop allergic reaction. Some of the causes of allergy that may be listed include-

  1. Certain foods such as peanuts, diary products, fish products, wheat.
  2. Allergic reaction in babies may be caused by milk, eggs, and soya beans.
  3. Vaccines and medications especially antibiotics like penicillin, amoxicillin, aspirin, ibuprofen, general anesthesia, medication gloves, condoms etc.
  4. Bee stings, snake bites may also trigger allergic reaction.
  5. Emotional stress, hot and cold temperatures, minor injuries may also result in an allergic reaction in some persons.
  6. Allergy may also be commonly inhibited in those who have certain medical conditions and also those who had a history of severe allergic reactions.
  7. The tendency to develop an allergy is inherited but allergies to specific allergens are not inherited.

Symptoms of allergy

The symptoms and signs of allergy are dependent upon on which body part it is involved in and the sensitivity towards the reaction. Some of the allergic reactions may be limited to a particular part of a body or are localized and in other cases they may spread to multiple body areas. The following are the allergy symptoms usually observed in an individual with an allergic reaction and these are:

  1. Anaphylaxis is a term used for combination allergic symptoms that is rapid, sudden and is life threatening. It also involves a shock that may possibly result in sudden death if proper medical attention is not given to the concerned person. The person in shock may be pale or sweaty and his or her skin may become reddish in color. The concerned person may also be confused, unconscious or anxious.
  2. Respiratory allergic symptoms may include nausea, difficulty in swallowing, tightness in throat, skin rashes. Stuffy, itchy and running nose.
  3. Other signs and symptoms of allergic reaction include some reactions of certain body parts as mentioned below:
    • Lungs: Cough, tightness or shortness of breath, wheezing
    • Head: There is a bump or swelling on the face or neck, headache, the voice becomes hoarse, eye lids become swollen.
    • Eyes: The eyes become reddish, itchy and watery discharge may happen in one or two eyes.
    • Stomach: There will be stomach pain, vomiting, nausea, diarrhea that may have stools with blood in them.