Dr. Gaurav Ghatawat
Chest Physician


Allergy is a hypersensitivity disorder in which the body’s immune system reacts to normally harmless substances in the environment. These substances which trigger an allergic reaction in the body are called allergens. Allergy can be caused by anything such as egg, wheat, peanuts, milk, drugs, house dust mites, unhygienic places, cold, rain and even dust. Food allergies are reactions towards certain food components. The most common allergens in foods are proteins. When the allergic reaction is due to a drug, it is said to be a drug allergy. They are most commonly seen with antibiotics followed by anti-tumour drugs.

Allergens cause an immune system response in the person’s body leading to symptoms such as sneezing, skin rash, hives, and itching of the skin or eyes, swelling of face or tongue, running nose, hoarseness of voice, cough, etc. Allergies can play a major role in conditions such as asthma. Drug allergy may cause swelling or tightening of the airways, dizziness or light headedness, rapid pulse, or even loss of consciousness. An anaphylactic attack or anaphylaxis is a severe type of allergic reaction which can often be sudden and cause severe symptoms like choking, organ failure and even death.

Depending on the type of allergy, diagnostic tests may include skin tests, blood tests, oral challenge test, drug provocation test, etc. Self-medication for allergy should be avoided. Allergy can be of many types and each one of them need separate medication to be cured. Special diets are the most commonly used treatment for food allergies. But, certain medications and supplements are also used to deal with food allergy symptoms. Adverse reaction to any drug must be notified to the doctor immediately. Epinephrine (adrenaline) injection is used to handle medical emergencies due to complications. An anaphylactic attack is a medical emergency.

Also Read


A person could be allergic to one or several allergens. There are different forms of allergies depending on the type of allergen triggering the response. Here are the most common forms of allergies that people suffer from.

1. Food allergy: Your immune system could trigger a response to proteins present in specific foods you consume. Allergies to nuts, egg, wheat, milk and chickpeas are more common, contributing to 90% of food allergies found in India.

2. Dust allergy: Dust particles can enter your nasal passage and cause blocked nose, cough, sneezing and irritation in the throat.

3. Seasonal allergy: Many people complain about allergic symptoms with a change in climate and season. 

4. Pet allergy: You could develop an allergic reaction to skin flakes, dander or saliva of your pet. Moreover, the fur of animals attracts dust and pollen that can worsen allergy symptoms.

5. Drug allergy: Your system could evoke an immune response to either the drug or the chemical generated inside the body by the drug. This type of allergy could be severe and may be fatal

6. Cosmetic allergy: Chemicals used in cosmetics can trigger an immune response causing allergic skin reaction and swelling.


Symptoms of allergies are triggered depending on the part of the system the allergen targets.

  • Dust, seasonal and pet allergy can cause congestion, runny nose, swollen eyes, watery eyes, throat irritation and blocked nose.

  • Food allergy can cause mouth and throat irritation, swelling of the mouth, indigestion, vomiting, nausea, stomach cramps, bloating and diarrhea. Some food allergens can also trigger respiratory symptoms like wheezing, runny nose, sneezing and coughing.

  • Drug allergy can cause itchy skin, redness, swelling, wheezing and skin rash

  • Cosmetic allergy can cause redness, swelling and flaking of skin. It can cause itching and skin rashes.

Certain allergies can become severe. If you develop any of the following symptoms, you should see a doctor immediately.

  • Difficulty in breathing or extreme shortness of breath

  • Tightness in the chest, congestion or chest pain

  • If eczema progresses to thickening and swelling of skin

  • Hives or itchy swelling on the skin

  • Anaphylaxis or a life-threatening allergic reaction

Causes And Risk Factors


Allergies are often genetic and are in the family. The body believes that an allergen, which is generally harmless to most people, is harmful and reacting to it as if it was a foreign body or germ. The body produces antibodies (IgE antibodies) in response to these allergens. These IgE are released during the first encounter with the allergen. The antibodies remain attached to the different cells in the body; when the body comes in contact with the allergen again, these cells release histamine, a chemical that is responsible for allergic symptoms. 


Risk Factors

Although an allergy may run in the family, if any person may be allergic depends on different factors such as environmental factors like air pollution and cigarette smoke. 

In sensitive people, the following can be risk factors for developing allergies:

  • Perfume

  • Stress

  • Smoke

  • Hormones


  • To prevent an allergic reaction, avoid the allergen as much as you can. You can do this in the following manner:

    • For a food allergy, you should read the list of ingredients in the food package and ask the server in the restaurant for the list of ingredients in the dish. 

    • For allergies to bee stings, you should avoid wearing any perfumes or bright clothes and avoid gardening or mowing the lawn such that you do not attract insects. 

    • If you are allergic to pollen, you should stay indoors as much as possible during pollen season and keep your doors and windows shut. If you are travelling by car, keep the air conditioner on and the external vents shut. 

    • Have a bath at night to remove all the pollen that may be accumulated on you during the day. Dry your clothes on a clothesline within the house or use a dryer. 

    • If you have a history of anaphylaxis, your doctor may recommend always keeping a shot of epinephrine (adrenaline) with you, and as soon as the symptoms occur, you should take it. 

    • If you have a dust allergy, you can prevent it by regular cleaning and using mite-proof bedding. 


To determine whether you are suffering from an allergic reaction, your doctor may recommend a simple blood test. ‘The general test for diagnosing allergies includes a complete blood count (CBC). If your results show an increased eosinophil level and IgE level, then you might be diagnosed with an allergy,’ says Dr Abha Shroff, Chief Pathologist and Director at Disha Pathology Labs, Mumbai. To determine the allergen causing the undesirable reaction, you may have to undergo the following tests:

Scratch Skin Test

A small drop of the suspected allergen is placed on the skin’s surface. Using a needle, the surface is scratched or lightly pricked so as to allow the allergen to get absorbed. Any immediate redness, swelling or change in the skin’s surface may indicate allergy toward the allergen under test. 


In certain situations, such as extensive eczema, skin tests cannot be performed because it may lead to dangerous consequences. In such cases, the doctor may recommend blood tests such as the radioallergosorbent assay (RAST) and the enzyme-linked immunosorbent assay (ELISA). Both the tests detect the presence of IgE antibodies in the blood of patients. They are expensive and the results are not readily available. ‘The newest advanced tests for allergy testing are blood tests that do not require fasting. The skin prick tests have been replaced by blood testing,’ says Dr Shroff.


Allergies cannot be cured; the best approach to prevent them is to avoid the allergen. However, for that, you require to undergo proper tests to identify the causative allergen.

Medicines given for allergies help reduce the symptoms and effect of substances released during an allergic reaction on the surrounding tissues. There are different groups of medications given for allergic reactions depending on the allergen triggering the reaction.


These are the most common class of drugs that relieve the symptoms of allergies. They work by blocking the action of substances or molecules called histamines that are released by your system when it detects an allergen. 


Decongestants are another class of medicines that may be given to relieve symptoms such as nasal congestion, often caused by dust allergy or pet allergy. 


They specifically act on the linings of the nasal passage and airways to clear congestion and reduce respiratory symptoms. Here is more information on side-effects, interaction and overdose of allergy medicines.


To avoid the allergen, an excellent approach to prevent an allergy is to make lifestyle changes. Some approaches to prevent allergies is by staying at home during the pollen season, using the air conditioner, keeping the windows closed, wearing a mask while gardening and regularly cleaning the curtains, clothes and bed linen.

Prognosis And Complications


Generally, allergies are managed by avoiding the allergen and using the available medications. For anaphylaxis, prompt medical attention can lead to complete recovery; however, if a person has had an anaphylactic reaction once, the risk of another anaphylactic reaction in the presence of the allergen is significantly higher. 


Anaphylaxis, which can be caused by an allergy to medicine, food, bug venom, serum, chemical or an allergen extract, is a life-threatening immune response to an allergen but is not common in allergies to pets, dust, mould, and pollen. An anaphylactic shock can manifest as difficulty in breathing, swelling in the throat and tongue, hives or itching all over the body, as well as dizziness, headaches and loss of consciousness.

Alternative Treatments

Research has shown that herbals, homoeopathy and acupuncture do not help in allergy treatment.


  1. MedlinePlus. Allergies [Internet][Updated Jun 17, 2012]. Available at:

  2. KidsHealth. All about allergies [Internet][Updated Oct, 2016]. Available at:

  3. Harvard Health Publishing. Allergy overview [Internet][Updated Feb, 2019]. Available at:

  4. Cleveland Clinic. Allergy overview [Internet][Updated Nov 30, 2020]. Available at:

  5. NHS. Diagnosis allergies [Internet][Updated Nov 22, 2018]. Available at:

  6. NHS. Treatment allergies [Internet][Updated Nov 22, 2018]. Available at: 7. U.S. Food And Drug Administration. Allergens in cosmetics [Internet][Updated Nov 12, 2020]. Available at: 8. American College of Allergy, Asthma & Immunology. When to see an allergist [Internet]. Available at:

  7. Allergies: Overview [Internet][Updated Apr 23, 2020]. Available at:

  8. University of Rochester Medical Center. Allergy overview [Internet]. Available at:

  9. MedlinePlus. Antihistamines for allergies [Internet][Updated May 30, 2020]. Available at:

  10. Corticosteroids [Internet][Updated Nov 21, 2015]. Available at:


Health Calculator

Photo Gallery

Don’t Miss Out on the Latest Updates.
Subscribe to Our Newsletter Today!

thehealthsite subscribe now