What are Allergies?

Time to read 11 min

Do you often find yourself sniffling through springtime? If so, you may have a seasonal allergy. An allergy is the body’s reaction, often misguided, to a foreign body generally called an ‘antigen’.

Every day, the human system is exposed to a variety of foreign particles. Some of these, such as some bacteria and viruses, are harmful to us. Others, such as pollen, dust and smoke are not infectious the same way as pathogens are, but are classified as ‘foreign bodies’ because they don’t belong in our systems.

When we are born, our immune system, comprising of White Blood Cells and Gut Bacteria, has no experience handling these foreign bodies. Over time, it ‘learns’ based on the different things it is exposed to. For example, the immune system learns that food is not harmful, while some viruses are.

However, in some cases, the system mistakes a perfectly harmless foreign object and reacts to it with its full arsenal drawn in a condition we call allergies.

 Our Gut consists of 80% of our Immune System

Allergy v/s Autoimmue:

Allergies & Auto-immune are disorders of the Immune system. It (Immune system) either attacks the body itself causing autoimmune disorders, while other times it attacks harmless foreign particles causing allergies. 

Allergy v/s Intolerance/Sensitivity:

Allergies are caused by the reaction of the immune system, whereas intolerances or sensitivity are caused by the reaction of the digestive system. Symptoms in both cases, sometimes are similar 

Types Of Allergies

 Based on the foreign body that causes the reaction and the symptoms that manifest, allergies can be classified into many different categories. Some allergies are just inconvenient to have, while others are potentially fatal. 

  1. Respiratory Allergies-

    • Allergic Rhinitis is mostly centred around the nasal passages in response to inhaled triggers (allergens). Symptoms include sneezing, congestion and watery eyes.
    • Not all sinusitis infections are allergic in nature. Sometimes, allergic rhinitis progresses and becomes sinusitis.
    • The most life-threating form of respiratory allergies is asthma. Triggers may be common with allergic rhinitis, but other factors such as stress and shock may also contribute. The airways swell up and make breathing difficult. Not intervening in time can lead to death. 

  1. Food Allergies-

 Food allergies are commonly caused by an adverse reaction to certain proteins in food. People are more commonly allergic to proteins in milk, nuts, eggs, shellfish, and soy. Gluten in wheat and other grains are also responsible for food allergies. Hives, vomiting, diarrhoea are common symptoms. Can quickly turn fatal if the epiglottis swells up and restricts breathing. 

  1. Insect Allergies-

Some people are allergic to the stings of different insects, most commonly bees. Hives and wheezing are the starting symptoms, and can quickly progress into respiratory distress, low blood pressure and anaphylactic shock.

  1. Drug Allergies-

 Some people are allergic to medications, especially those obtained from natural sources such as antibiotics and some anti-seizure medications. A patch test is often done if a drug allergy is suspected. 

  1. Skin Allergies- 

  • Contact Dermatitis: Literally anything can cause this condition in which the exposed area of the skin begins to develop a rash and itch severely. Common culprits include detergent residues, chemicals in cosmetics and poison ivy.
  • Eczema: Hypersensitive skin caused due to a chronic form of contact dermatitis. There is no known permanent cure.

Global Statistics And Prevalence

 In the United States, allergies are the most common chronic conditions and hay fever affects roughly 10% of all adults, and children. 

 In the United Kingdom, it is estimated that 44% of the populations suffers from one allergy or another. 

Nearly 550 million people, both adults and children, suffer from allergies the world over. Asthma alone is expected to affect 400 million people the world over by 2025. 

In India, no definitive studies exist for the population as a whole regarding allergies. In general, allergies are not considered a major health emergency. However, that situation may be changing rapidly.  

One of the most touted, and most controversial, theories around this subject is the hygiene hypothesis which states that developed countries are too clean for our own good. The hypothesis states that we need to be exposed to a certain kind of foreign matter in our lifetime to develop resistance to it so that we are not allergic to it. 

However, we cannot discount the fact that exposure to harsher environments, especially in children, can also expose them to a whole host of infections, some of which are quite hard to treat. 

Causes- What puts people at risk?

Our immune system is primarily composed of white blood cells, and the substances they produce to fight off infections, heal a wound and so on.

One of the many compounds produced by this system, called the IgE antibody, is the most sensitive and immediate marker of hypersensitivity in people prone to allergies.. To be sure, IgE is an essential antibody in identifying and binding with foreign bodies, but it has been noticed that those who suffer from allergies produce greater amounts of IgE antibodies for a particular trigger than those who don’t.

However, the precise cause of this condition is not known. Why do some people produce more IgE than others? Some research is linking allergies to the balance of our gut bacteria. There is a reason to believe that some flora in our intestines regulate which triggers we may be allergic to.  

There are, however, three main factors that may put people at risk: 

  • Genetics- You inherit certain immunity and immune conditions from your family and hence it is safe to say that genes play a role in determining how one’s immune system reacts to antigens. For example, although some people may not be allergic to peanuts as such, their body may produce IgE because of the allergy genes inherited (e.g. MCM6 for Lactose, 

HLA-DQ 2.5, HLA DQ2.2 (M3)),The reaction in such cases is mild and may however not be strong enough to be classified as a peanut allergy.

  • Environment- Environmental allergies are reactions caused due to external factors relating to your surroundings. Exposure to pollen, dust, mold, etc. can cause a person to develop strong reactions such as hay fever, nasal congestions and the kind. As the levels of particulate pollutants go up in cities, respiratory allergies like asthma are on the rise too. Case in point- New Delhi, with an air quality score of 305, is very unhealthy for all outdoor activity.

  • Food- This probably is the most commonly found and diagnosed type among allergies. As discussed earlier, the body recognizes food as an acceptable foreign substance. However, be it genetics or body’s natural reaction, it refuses to accept certain proteins in foods. It is also understood now that certain chemicals in processed and packaged foods are quite capable of producing allergies.

Diagnosis- The Symptoms

The first exposure to a trigger causes a very mild reaction, and this is often dismissed as a passing allergy. Also, different allergies have different symptoms, some of which are similar to other afflictions. Sometimes, it is hard to distinguish allergic conjunctivitis from bacterial or viral conjunctivitis. Likewise, diarrhea and vomiting can also occur with intolerances and not just food allergies. 

If you suspect an allergy, your healthcare practitioner may ask you to maintain a diary of all the things you eat, drink and are exposed to over a time period to identify the triggers.

Caution: Allergies can turn life-threatening in a matter of minutes. Please refer to the symptoms here and rush to a medical center if critical symptoms are observed.

It is also extremely difficult to pinpoint allergies in children. Most doctors do not recommend introducing allergens such as nuts until later in life, and children often come home with a sniffle or two once they begin school anyway.

A list of common symptoms to watch out for:


  • Swelling of the fingers and toes.
  • Tightness in the chest and throat
  • Breathlessness
  • Blurring vision
  • Hives on the skin


  • Rashes
  • Allergic Conjunctivitis
  • Runny nose
  • Watery eyes
  • Diarrhea
  • Nausea and vomiting

Assessments And Tests

Blood Tests

Blood tests take longer than skin tests to show results but the benefit is that a single pinprick is often enough, as opposed to the multiple pricks involved in skin tests. Sometimes, blood tests for allergies are known to return false positive results. 

Skin Tests

A whole gamut of triggers can be tested at the same time through a skin test. Often, small amounts of triggers are introduced just below the epidermis on the backs of patients. Skin tests can be conducted in people of all age groups.

Results in a skin test are measured by the degree of induration (swelling) and can be obtained very fast. However, the risks include developing a severe reaction while being tested. This is why it is important to be tested in a controlled environment where treatment is readily available.

Gut Microbiome Tests

Studies on gut microbiome in patients with known allergies have shown that their gut flora is less diverse in species than people who have no allergies. Gut microbiome tests prove a valuable resource in identifying a possible treatment plan for those with chronic allergies. 

Post-Diagnosis: The Path To Follow

 Being diagnosed with an allergy of a certain degree of severity can feel very frustrating and overwhelming. However, you can seek help from online forums, friends and counsellors to overcome these fears. 

1. Medications 

Medically, there is no long-term treatment prescribed for allergies. Allopathic medicine considers allergies to be permanent. The more severe cases are prescribed an EpiPen to help keep them safe in case of emergencies. 

1.1.Conventional Treatments

Medicines of the antihistamine class are prescribed for acute allergies, while chronic allergies are often treated using corticosteroid medication over a longer time period. It is essential that you follow medical advice and never stop medication midway.

Immunotherapy, the process of desensitization using small, but increasing, doses of the trigger is being advocated in some circles, but there is not enough research to corroborate its mainstream usage for all types of allergies. 

1.2 Alternative Treatments 

Non-conventional treatment modes such as homeopathy may be very effective in dealing with and curing allergies. In several tests conducted in clinical conditions, respiratory allergies showed marked improvement in a short span of time. [7]

However, no such studies exist for food allergies and other allergies with the potential to turn fatal. It is therefore advised that you keep your entire medical team in the loop about any alternative treatments you might consider.

Considering that most allergies are chronic conditions, you may need to make a few adjustments to your lifestyle and habits. 

2. Nutrition

If you have a food allergy that is particularly debilitating such as an allergy to milk protein, you need to consult with a nutritionist and find ways to supplement the loss of nutrients through this food source. In most cases, it is a simple transition from eating a certain group of foods to avoiding them altogether, but the transition does take time. 

In children diagnosed with milk protein intolerance, it may be worthwhile to explore other nutrition options as they need a lot of protein and calcium in the growing phase.

Supplements such as Spirulina and seeds of Nigella sativa have shown some promise as immunoboosters and can help strengthen the immune system. 

3. Movement

 If you are an active individual and discover that you have developed respiratory allergies, you may be a bit disappointed. However, do note that even people with allergic rhinitis and asthma can exercise and lead an active lifestyle as long as they avoid the triggers that set of allergic reactions. 

Research backs the fact that asthma symptoms can be managed much better by working out more! As long as asthma is being managed medically, and you can tell when you are exhausted vs. when an asthma attack is coming, you are encouraged to consult with a trainer and begin with a good cardio workout especially Interval Training 

Did you know that David Beckham is asthmatic?

 There are many athletes who have performed well in both high-intensity and endurance sport by managing their asthma effectively and staying active. 

So, getting into that swimming pool or running that marathon (under medical advice) is just what you probably need to reset your mood, and to build a healthy habit in spite of allergies. 

4. Mindset

 Allergies can certainly cause anxiety in patients and their caregivers. If you have experienced anaphylactic shock, you may feel anxious and panicked in some situations. Cognitive-behavioral therapy is shown to help in such cases. Speak to a licensed counsellor for the most effective treatment plan for you. 

Another, oft ignored, group of individuals are caregivers of young patients. It can be very stressful for parents and guardians of young children as they are always on their toes trying to prevent an emergency. CBT, mindfulness and visualisation are shown to help such people, and it is a good idea to join a support group for caregivers.  

5. Recovery

 If you are an otherwise healthy adult suddenly experiencing allergic rhinitis, it may be worthwhile exploring the balance of gut flora in your body and supplementing probiotics to see a difference. 

Adequate sleep and rest is a much-needed attribute in today’s fast-paced lifestyles. Stress in itself can set off inflammation and immune compromise in our bodies. It is very important to get enough rest for both the body and the mind to first prevent allergies, and to also prevent recurrence as much as possible. 

Prevention- How to reduce risks:

 There is no way to vaccinate oneself against allergies, so to speak. However, one sure can prevent them to their best. 

  • Test and know your allergens-

If you have allergic rhinitis, or food allergies, an allergen test can help you identify which component in air or food is causing the allergy. You can then proceed to avoid that trigger. 

  • Avoid the trigger-

If you have been diagnosed as being allergic to a substance/ substances, the single most effective way to prevent an allergy is to avoid the trigger entirely. If you have a food allergy, avoid the trigger and even environs where it is being used in cooking. Be sure to communicate this to hosts when you visit for a meal. 

  • Carry medications-

In cases of allergy to insect venom, or severe allergies to food, it is recommended that you always carry a shot of epinephrine in order to halt the progress of an allergy until you can get to the emergency room. Those suffering from asthma are advised to avoid triggers as much as possible, and to carry a prescribed inhaler at all times to prevent a severe attack. One can also carry Antihistamines along. However, caution must be taken in using them as they can have severe side effects. 

 *Medical Disclaimer - The following information is for educational purposes only. No information provided on this website, including text, graphic, and images, are intended as substitutes for professional medical advice. Please consult with your doctor about specific medical advice pertaining to your condition(s)

Tests to consider

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