Health Tips

Do you know what are you allergic to? (Part 1)

Allergies occur when there is an overactive immune system in the body after exposure to some foreign substances (allergens) that are usually harmless in most people, such as pollen or certain foods. The symptoms are quite mild in some cases, but they can also be a real nuisance and impact our everyday lives.

Are you allergic to one of the following allergens?

• Pollen

• House dust mites (e.g. on the bedsheet)

• Pets and farm animals

• The poison in insect stings and bites

• Foods (Understand more about food allergy here)

• Medications

• Contact allergens (e.g. metals in jewelleries or fragrance ingredients in perfumes)

• Mold 

If you are allergic to one of the mentioned allergens, you might have experienced allergic reactions on the skin or in the airways, which usually start right away after contact with the allergen, or up to a few hours or days for the reactions to appear.

What are the allergy symptoms?

• Runny nose, coughing, and sneezing (signs of allergic rhinitis)

• Chest tightness, having difficulty in breathing

• Itchy, red, watery eyes

• Swollen lips/ tongue/ eyes/ face

• Raised red, itchy rashes (hives)

Allergic reactions usually occur in the areas of the body that come into direct contact with the allergen. For instance, the first part of the body that pollen comes into contact with is the upper part of the airway, resulting in a runny nose and sneezing. Whereas, food can cause itching and swelling in the mouth and on the tongue. 

Dust mite allergies and pet fur allergies can be a problem all year round because the allergens aren't only found seasonally. Although allergies to medications and insect venom are only triggered in certain situations, they are often more severe than other kinds of allergies.

The most severe form of allergic reaction is the anaphylactic reaction. This is a medical emergency and can become life-threatening. It happens when the allergic reaction starts affecting and involves other parts of the body system too – such as the digestive tract, the airways, or the heart and blood vessels. Anaphylactic reactions can cause generalised itching, swelling, stomach ache, nausea, vomiting, confusion, lightheadedness, breathing difficulties, wheezing and a sudden drop in blood pressure.

Why does the immune system overreact to allergens?

In allergic reactions, the body's immune system reacts to certain foreign proteins, such as allergens, that are usually harmless to most people. For instance, although dust mites and foods generally don't cause any problems in the body, they trigger a reaction in people who are allergic to them. The immune system produces IgE antibodies to fight these substances because it considers them to be harmful.

These antibodies are made when the body first comes into contact with the allergen, and they then attach to certain kinds of cells (mast cell). This process is called “sensitization.” If the body is exposed to the same allergen again, these cells release chemical substances, including histamines, which can lead to allergic reactions such as sneezing, coughing, and skin rashes.

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The tendency to have allergies often runs in families. Some conditions which are closely related to allergic reactions include asthma and eczema.

So can you know beforehand what are you allergic to?

Actually, we cannot know we are allergic to something until we come into contact with or ingest it. Hence, if you have an allergic reaction as mentioned above, do get advice from your doctor who will then ask about the symptoms you experience, when and how frequently they occur, and also if there is an obvious allergen that triggers these reactions. In the event that your allergy is severe or you are unsure of what causes you to have an allergic reaction, there are few tests available that can help. Read part 2 to learn about the allergy tests and the treatments available.

Medically reviewed by Ashwini Nair, MB BCh BAO.

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References:

1. Allergies: Overview. Institute for Quality and Efficiency in Health Care (IQWiG); 2020. Accessed April 14, 2022. https://www.ncbi.nlm.nih.gov/books/NBK447112/

Written by

DOC2US Editorial Team