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What Causes Allergies?

Know all about allergies, causes, common allergens, who gets allergies, how it affects your health, and learn to manage and prevent allergies.

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Written by Dr. J T Hema Pratima

Reviewed by Dr. Vasanthasree Nair MBBS

Last updated on 22nd Jul, 2025

Allergies

What Causes Allergies?

Introduction

Allergies are a common health issue that affects millions of people worldwide. If you've ever sneezed uncontrollably around pollen, broken out in hives after eating certain foods, or felt your throat tighten after a bee sting, you've experienced an allergic reaction. But what exactly causes allergies, and why do some people suffer from them while others don’t? Let’s break it down in simple terms.

Understanding Allergies

An allergy is your immune system’s overreaction to a harmless substance (called an allergen). Normally, your immune system fights germs like bacteria and viruses to keep you healthy. But in people with allergies, the immune system mistakes harmless things—like pollen, pet dander, or certain foods—as dangerous invaders and attacks them. This reaction leads to allergy symptoms.

Common Allergens (Triggers)

Allergies can be triggered by various substances, including:

1. Airborne Allergens

Airborne allergens include:

  1. Pollen (from trees, grass, or weeds)
  2. Dust mites (tiny bugs in household dust)
  3. Mold spores (found in damp areas)
  4. Pet dander (skin flakes from cats, dogs, or other animals)

These often cause hay fever (allergic rhinitis), leading to sneezing, a runny nose, itchy eyes, and congestion.

2. Food Allergens

Common food allergies include:

  1. Milk
  2. Eggs
  3. Peanuts & Tree nuts
  4. Shellfish
  5. Wheat & Soy

Food allergies can cause mild reactions (itching, hives) or severe ones (swelling, difficulty breathing, called anaphylaxis).

3. Insect Stings & Bites

Stings and bites due to:

  1. Bee or wasp stings
  2. Mosquito bites
  3. Fire ant bites

Some people develop severe swelling or anaphylaxis from insect venom.

4. Medications

Certain drugs (like penicillin or aspirin) can trigger allergic reactions, ranging from rashes to life-threatening responses.

5. Skin Contact Allergens

Skin contact allergens include:

  1. Latex in gloves, balloons
  2. Nickel in jewellery, watches
  3. Cosmetics or perfumes

These can cause contact dermatitis, leading to redness, itching, or blisters.

Consult a Top general practitioner for the best advice

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Dr D M Karthik

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Dr. Vasanthasree Nair

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Why Do Some People Get Allergies?

The exact reason why some people develop allergies isn’t fully understood, but several factors play a role:

1. Genetics

If your parents have allergies, you’re more likely to develop them too.

2. Environment

Growing up in overly clean environments (the hygiene hypothesis) may make the immune system more prone to overreacting to harmless substances.

3. Early Exposure

Babies exposed to certain allergens early (like peanuts in controlled amounts) may have a lower risk of allergies later.

4. Immune System Sensitivity

Some people’s immune systems are just more reactive to allergens.


How Allergies Affect Your Health?

Allergic reactions can range from mild to severe:

  1. Mild: Sneezing, itching, watery eyes
  2. Moderate: Rash, swelling, stomach upset
  3. Severe (Anaphylaxis): Trouble breathing, dizziness, rapid pulse. This is a medical emergency.

Long-term untreated allergies (like chronic hay fever) can lead to:

  1. Sinus infections
  2. Asthma flare-ups
  3. Eczema (skin irritation)
  4. Sleep problems (due to congestion)

Managing & Preventing Allergies

While allergies can’t always be cured, they can be managed effectively. Here’s how:

1. Avoid Triggers

  1. Keep windows closed during high pollen seasons.
  2. Use dust-proof covers on mattresses and pillows.
  3. Wash your hands after petting animals.
  4. Read food labels carefully.

2. Medications

  1. Antihistamines like cetirizine block allergy symptoms.
  2. Nasal sprays reduce congestion.
  3. Epinephrine auto-injectors for severe allergies treat anaphylaxis.

3. Allergy Shots (Immunotherapy)

For long-term relief, doctors may recommend allergy shots, which gradually desensitise your immune system to allergens.

4. Home Remedies

Saline nasal rinses help clear pollen from the nasal passages.
Honey (local) may help with mild pollen allergies, though evidence is limited.
Air purifiers reduce indoor allergens.

When to See a Doctor?

Consult a doctor if:

  1. Symptoms interfere with daily life.
  2. Over-the-counter meds don’t help.
  3. You experience wheezing, throat swelling, or dizziness (seek emergency care).

Final Thoughts

Allergies can be frustrating, but understanding their causes and managing them properly can make a big difference. Whether it’s avoiding triggers, taking medications, or seeking professional help, you have options to live comfortably. Stay informed, stay prepared, and breathe easy.

Consult a Top general practitioner for the best advice

Dr D M Karthik, General Practitioner

Dr D M Karthik

General Practitioner

4 Years • MBBS, Fellowship in Diabetes Mellitus, Advance certificate in Diabetes Mellitus, Derma Nutrition Certification

Visakhapatnam

Apollo 24|7 Clinic - Andhra Pradesh, Visakhapatnam

449

44 Cashback

Dr. Vasanthasree Nair, General Practitioner

Dr. Vasanthasree Nair

General Practitioner

15 Years • MBBS

Angamaly

Apollo 24|7 Clinic - Kerala, Angamaly

recommendation

87%

(425+ Patients)

699

105 Cashback

Dr. Riti Srivastava, General Practitioner

Dr. Riti Srivastava

General Practitioner

12 Years • MD (Physician)

Gautam Buddha Nagar

Shri Krishna Clinic, Gautam Buddha Nagar

750

600

Consult a Top general practitioner for the best advice

Dr D M Karthik, General Practitioner

Dr D M Karthik

General Practitioner

4 Years • MBBS, Fellowship in Diabetes Mellitus, Advance certificate in Diabetes Mellitus, Derma Nutrition Certification

Visakhapatnam

Apollo 24|7 Clinic - Andhra Pradesh, Visakhapatnam

449

44 Cashback

Dr. Syed Ismail Ali, General Practitioner

Dr. Syed Ismail Ali

General Practitioner

7 Years • MBBS

Hyderabad

Apollo 24|7 Clinic, Hyderabad

499

49 Cashback

Dr. Vasanthasree Nair, General Practitioner

Dr. Vasanthasree Nair

General Practitioner

15 Years • MBBS

Angamaly

Apollo 24|7 Clinic - Kerala, Angamaly

recommendation

87%

(425+ Patients)

699

105 Cashback

Dr. Riti Srivastava, General Practitioner

Dr. Riti Srivastava

General Practitioner

12 Years • MD (Physician)

Gautam Buddha Nagar

Shri Krishna Clinic, Gautam Buddha Nagar

750

600

Dr. Ritesh Motghare, General Practitioner

Dr. Ritesh Motghare

General Practitioner

18 Years • MBBS PGCDM

Nagpur

HEALTH CENTRE VNIT NAGPUR, Nagpur

250

200

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