There are a number of different allergies, from foods and pharmaceuticals to insect stings and airborne allergens. Depending on the type of allergy a person has, they may need to take action to avoid coming into contact with the things they’re allergic to or minimize the damage they can do, such as avoiding eating certain ingredients, using insect repellents or taking antihistamines before visiting friends and relatives who have pets. But which allergens most commonly cause people health problems, and how do they affect those who are allergic to them? Before learning the answers to these questions, let’s start by exploring what allergies are and how allergic reactions develop in the body.
What is an allergy?
When a person has an allergy, their body responds inappropriately when it comes into contact with a substance that is normally harmless for most people. The person’s immune system incorrectly identifies the substance – known as an allergen – as harmful and produces antibodies to fight the perceived attacker. Allergens can be foods, drugs, insect venom or airborne particles like pet dander or pollen. Some people can also have an allergic reaction when they touch substances like nickel, a magnetic metal or latex, an organic material that’s used to make rubber. Allergies often develop in childhood and they can be present for a person’s whole life, although over time allergies can also develop, disappear, or become more or less severe.
Although symptoms can vary widely, there is a particular process that the body goes through when someone has an allergic reaction:
- When the body detects the presence of an allergen, it produces antibodies – this can take seconds, minutes or hours.
- These antibodies attach themselves to cells known as mast cells, which contain a chemical called histamine, a compound that is involved in immune responses, among other processes.
- When the allergen comes into contact with the antibodies the mast cells release histamine, causing inflammation that is uncomfortable and irritating (this is why drugs called antihistamines are often used in the treatment or prevention of allergic responses).
How do people respond to allergens?
An allergic reaction occurs when someone ingests, breathes in or touches something they’re allergic to. Reactions can vary significantly in seriousness – in some cases, a mild tingling or minor irritation is all a person will experience, while in others the body’s response can prove fatal. The “worst case scenario” of allergic reactions is anaphylaxis. This is when an allergic reaction is so strong and rapid that a medical emergency occurs. Anaphylaxis often causes swelling that can close the throat and prevent breathing, with other signs and symptoms including vomiting, loss of consciousness, shock and even death. In the case of anaphylaxis, immediate medical intervention is required and many people with severe allergies to foods, medications or insect stings carry adrenaline as a precaution.
Other common allergic responses include digestive discomfort or diarrhea, swelling and itchiness in the mouth, eyes, nose, sinuses and airways, and skin irritation, hives and rashes. These various symptoms are typically associated with different allergens – for instance, food allergens like peanuts and shellfish can cause a swollen mouth, digestive discomfort and anaphylaxis, while airborne allergens such as pollen, dust mites, fungal spores and pet dander tend to produce symptoms around the face and airways including a runny nose, streaming eyes and a sore throat, as well as swelling and itchiness. It’s also worth noting that intolerances to foods like lactose and gluten, although similar in some ways, are not technically allergies.
What are the four most common allergens?
Identifying the most common allergens is not as simple as it may seem, as there are different ways of measuring and categorizing them, and results can vary from one country to another. However, the four allergens that most often appear on allergy organizations’ lists as being the most common are pollen, pet dander, foods and dust mites. Other allergens that also feature heavily are mold, medications, insect bites and latex. These allergens can be categorized as airborne (pollen, pet dander, dust mites, mold), ingested (foods, medications), stings (insect bites) and contact (latex) allergens.
This table gives some additional details about the top 4 allergens:
|Allergen||Type||Examples||Typical signs and symptoms|
|Pollen (hay fever)||Airborne||Tree pollen, grass pollen||Sneezing, itchy mouth or throat, itchy, runny or stuffy nose, watery, itchy, red or swollen eyes|
|Pet dander||Airborne||Cat fur, dog fur||Sneezing, itchy mouth or throat, cough, itchy, runny or stuffy nose, postnasal drip, watery, itchy or red eyes, facial discomfort, difficulty sleeping, swollen reskin under the eyes|
|Foods||Ingested||Gluten, peanuts, tree nuts, crustaceans, sesame seeds, soya||Tingling and swelling in the mouth, lips, tongue, face or throat, hives, anaphylaxis|
|Dust mites||Airborne||House dust mites||Sneezing, itchy mouth or throat, cough, runny or stuffy nose, postnasal drip, watery, itchy or red eyes, facial discomfort, swollen blue skin under the eyes|
Airborne allergens are everywhere
As you can see, most of the main allergens are airborne. As well as pollen, pet dander and dust mites in the table above, mold spores are another common allergen that is found almost everywhere we go. Not only are airborne allergies extremely common, the allergens that cause them are arguably some of the most difficult to avoid or manage, because unlike food or pharmaceutical drugs, they are often impossible to avoid. Pollen is all around us during certain times of the year and it’s hard to avoid coming into contact with pet dander in indoor public places or other people’s homes. Meanwhile, at least some dust mites and mold are present in most buildings, no matter how well they are managed.
That’s why at Respiray, we’ve been working hard to develop Wear A+, a wearable air purifier that is worn around the neck and can protect people suffering from airborne allergies by filtering the air around them and providing clean, allergen-free air for them to breathe.