What Is Allergy and Why Does It Happen? – Dr. Dipak Viradia

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What Is Allergy and Why Does It Happen? – Dr. Dipak Viradia

October 17, 2026

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Why does one person sneeze around dust while another feels nothing? Why do some children with skin allergy later develop asthma? Understanding how allergy works helps patients take it seriously and treat it correctly. In this video, Dr. Dipak Viradia, Chest Physician & Intensivist, explains what allergy is and why it happens.

Allergy in simple words. Our immune system protects us from harmful germs like viruses and bacteria. In people with allergy, the immune system mistakes a harmless substance, such as dust mites, pollen, pet dander or a food, for a threat, and reacts against it. These harmless substances are called allergens.

How an allergic reaction happens:

  1. First exposure (sensitisation). The first time an allergic person comes in contact with an allergen, the immune system produces special antibodies called IgE against it. There are usually no symptoms at this stage.
  2. Repeated exposure. The next time the same allergen enters the body, these IgE antibodies recognise it and trigger certain cells to release chemicals such as histamine.
  3. Symptoms appear. Histamine and other chemicals cause swelling, itching, mucus production and tightening of the airways, leading to sneezing, runny nose, itchy eyes, rash, cough or wheezing, depending on where in the body the reaction happens.

This is why allergy symptoms can appear within minutes of exposure, and why the same trigger causes symptoms again and again.

Why do some people get allergies and others don’t?

  • Family history: allergy tends to run in families. If one or both parents have allergy or asthma, the child’s risk is higher.
  • Environment: air pollution, smoke, damp homes with mould, and constant exposure to dust mites increase the risk.
  • Early-life factors: researchers believe changes in lifestyle and early exposure to microbes may influence how the immune system develops. This is still being studied.
  • Second-hand smoke: children exposed to tobacco smoke are more likely to develop allergy and asthma.

The allergic march. In many children, allergy appears in a sequence over the years: skin allergy (eczema) or food allergy in infancy, followed by nasal allergy, and later asthma. Recognising and treating allergy early helps control symptoms and protect the airways.

Can allergy be controlled? Yes. Allergy is a long-term tendency, but with proper diagnosis (allergy tests and lung function tests), avoiding triggers, the right medicines, and allergen immunotherapy in selected patients, most people can live comfortably and keep their symptoms under control.

Dr. Dipak Viradia
Chest Physician & Intensivist | Interventional Pulmonologist & ECMO Specialist
Rudrax Chest Clinic, 301, Solaris Royce, Opp. Old RTO, Athwagate, Ring Road, Surat – 395001
Appointment: +91 75676 19985
Website: www.drdipakviradia.com

Frequently Asked Questions

Allergy is a condition in which the immune system wrongly reacts to a harmless substance, such as dust, pollen, pet dander or food, causing symptoms like sneezing, itching, rash or breathlessness.

In allergic people, the immune system produces IgE antibodies against a harmless substance. On repeated exposure, these trigger the release of histamine and other chemicals that cause allergy symptoms.

Allergy tends to run in families. Children of parents with allergy or asthma have a higher chance of developing allergy, though environment also plays an important role.

Allergy is a long-term tendency, but it can be well controlled with trigger avoidance, the right medicines, and allergen immunotherapy in selected patients.