Allergies and asthma are two common conditions that often get mentioned together. Many people suffer from one or both, and their symptoms can sometimes overlap, causing confusion.
In the US, asthma affects more than 28 million people, while over 100 million experience some type of allergy each year. Understanding the difference between asthma and allergies is important for getting the right treatment and managing your health.
This article will explain what allergies and asthma are, how they differ, how they are related, and why knowing the distinction matters for your well-being.
What are allergies?
Allergies are an immune system reaction to substances that are normally harmless. When you have an allergy, your body’s defense system overreacts to a specific trigger, called an allergen. This can include:
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- pollen
- dust mites
- pet dander
- certain foods
- insect stings
During an allergic reaction, the immune system releases chemicals such as histamine that cause classic allergy symptoms. Common allergy symptoms include:
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- sneezing
- runny or stuffy nose
- itchy or watery eyes
- skin reactions like hives or rashes
For example, someone with hay fever (a pollen allergy) may experience nasal congestion, sneezing, and itchy eyes whenever exposed to pollen. In more severe cases, allergies can lead to anaphylaxis, a life-threatening reaction that involves difficulty breathing, swelling, a drop in blood pressure, and other severe symptoms.
What is asthma?
Asthma is a chronic lung disease that makes it hard to breathe due to ongoing inflammation and narrowing of the airways. In asthma, the bronchial tubes (the air passages in the lungs) become inflamed and overly reactive.
When exposed to certain triggers, the muscles around these airways tighten (bronchospasm), and the lining of the airways swells and may produce extra mucus, causing the airway openings to become smaller.
This leads to asthma symptoms such as:
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- wheezing
- coughing
- shortness of breath
- chest tightness or pain
Asthma triggers vary from person to person. Some common triggers include:
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- respiratory infections (like a cold or flu)
- exercise
- cold air
- tobacco smoke
- air pollution
- strong odors
- stress
- allergens such as pollen or dust
When asthma symptoms worsen acutely, it’s often called an asthma attack or flare-up. Asthma attacks can become life-threatening if not treated promptly, as very inflamed and constricted airways can prevent enough oxygen from getting in.
On average, about 9 people in the US die from asthma each day, and nearly all asthma-related deaths are preventable with proper treatment.
What is the difference between asthma and allergies?
Allergy is an immune reaction to an external allergen (food, pollen, dust, etc.), often visible as sneezing, a runny nose, and itchy eyes/skin, which occurs upon exposure to the allergen.
On the other hand, asthma is a chronic lung condition with inflamed airways, causing coughing, wheezing, and difficulty breathing. It can be triggered by various factors, which might include allergens or other irritants, and requires long-term management of airway inflammation.
Here are ways to tell an asthma attack apart from an allergic reaction:
1. Where the reaction occurs in the body
Allergies and asthma are different conditions, even though they are sometimes related. The easiest way to distinguish them is to look at where in the body the reaction is happening:
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- Allergies (such as hay fever) usually involve the upper airways or skin. If the reaction is in your nose and sinuses, you’ll have sneezing, congestion, a runny nose, and itchy eyes. If it’s a skin allergy, you might get rashes or hives. These symptoms are the result of your immune system responding to an allergen on those surfaces.
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- Asthma involves the lower airways (lungs). If the reaction is in your lungs, you’ll experience wheezing, coughing, shortness of breath, and chest tightness, which are signs of an asthma attack. In asthma, the problem is narrowed bronchial tubes deep in the chest.
In short, the difference between asthma and allergies lies in the location and nature of the reaction. An allergy is an immune response that can affect various parts of the body, often starting in the nose, eyes, or skin, whereas asthma is specifically a lung condition causing breathing difficulty.
2. Consider whether the condition is chronic or exposure-based
Another difference is the type of condition each one is:
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- Asthma is a chronic respiratory disease. It’s an inflammatory disorder of the airways that tends to be long-term, though symptoms come and go. Even when not having symptoms, a person with asthma has underlying airway inflammation and hyper-reactivity. It requires ongoing management, similar to other chronic conditions.
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- An allergy is an immunological condition or reaction. These allergic reactions occur only when exposed to allergens. For example, a person with a peanut allergy will have symptoms only if they consume peanuts. Allergies can be chronic in the sense that you may always have the tendency to react, but avoiding the allergen prevents symptoms.
3. Look at how symptoms present
Symptom patterns differ between allergies and asthma. Allergies often cause visible outward symptoms like sneezing, a runny nose, itchy red eyes, or a rash, whereas asthma’s symptoms are mainly related to breathing. You might notice a person with asthma wheezing or coughing, especially during exertion or at night.
A person with pure nasal allergies with no asthma may complain of sinus pressure and sneezing, but will not typically feel chest tightness or wheezing. Conversely, someone in the middle of an asthma attack usually isn’t sneezing or itching their eyes, but is struggling to breathe and may be coughing.
Although there is some overlap. For instance, a bad allergy day could cause some coughing from post-nasal drip, and many people with asthma can also get a runny nose during attacks. But generally, the core symptoms are distinct from each other.
4. Notice patterns related to exposure, timing, and season
The timing and triggers can also differ. Allergy symptoms usually come on immediately or very soon after exposure to the allergen and last as long as that exposure continues. Asthma symptoms might be immediate as well. For instance, exercise-induced asthma can cause wheezing during or right after exercise. However, they can also be delayed or build up over time, and they might linger even after the trigger is gone until treated.
Also, asthma symptoms can flare up at certain times, like nighttime or early morning coughing, even without an obvious immediate trigger.
Allergies often have a seasonal pattern, whereas asthma can be year-round. That said, many people’s asthma is worse during allergy season if their asthma is allergy-related.
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Is asthma an allergic reaction?
Asthma is not inherently an allergic reaction. However, in many people, exposure to an allergen can set off an asthma attack. This type of asthma is known as allergic asthma or allergy-induced asthma, and it is very common. Roughly 60% of asthma cases are allergy-induced.
If your asthma is allergic, what’s happening is that when you inhale something you’re allergic to, like pollen, mold spores, dust mite debris, or pet dander, your immune system responds just as it would with any allergy.
It produces IgE antibodies and releases inflammatory chemicals, such as histamine and leukotrienes. This immune response in the lungs causes the airway inflammation and tightening characteristic of an asthma attack.
In other words, the allergic reaction sets off the asthma symptoms.
Not all asthma is caused by allergies, though. There are many people who have asthma symptoms triggered by non-allergic factors, such as:
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- exercise
- viral infections (like a cold)
- cold air
- smoke or air pollution
- strong chemical fumes
- stress
- acid reflux
This is sometimes called non-allergic asthma (or intrinsic asthma), as opposed to the allergic (extrinsic) asthma.
It’s important to determine whether your asthma has an allergic component. Studies have shown that a history of atopic disease (allergic conditions) is the strongest risk factor for developing asthma. Research also indicates that roughly two-thirds or more of people with asthma also have some form of allergy.
Symptoms of allergy-induced asthma
According to the Cleveland Clinic, people with allergic asthma experience the usual asthma symptoms, such as:
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- shortness of breath
- wheezing
- frequent coughing (especially at night)
- chest tightness
Additional symptoms that go along with allergic asthma can include:
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- a stuffy or runny nose
- sneezing
- itchy or watery eyes
- skin reactions like rash or hives
If you observe this pattern in yourself or a family member, mention it to a healthcare provider. They may perform tests to confirm asthma, like spirometry and allergy tests to identify triggers, which can guide more effective management.
Diagnosing allergies vs. asthma
The diagnostic approaches to allergies and asthma are different. Here’s how:
Diagnosing allergies
Allergists use a combination of medical history and allergy tests. The most common tests are skin prick tests and allergy blood tests, such as measuring allergen-specific IgE levels.
In a skin prick test, tiny drops of suspected allergens are scratched or pricked into the skin, often on the forearm or back, to see if a localized allergic reaction (a raised, red bump called a wheal) occurs. A positive reaction indicates an allergy to that substance.
Blood tests can also check for IgE antibodies to specific allergens in the bloodstream. These tests help pinpoint exactly what you’re allergic to.
Sometimes, a doctor may perform an elimination challenge, especially for food allergies, where the suspected allergen is removed from the environment/diet and later reintroduced to see if it causes symptoms. This is done under medical supervision.
Diagnosing asthma
The primary tool to diagnose asthma is lung function testing.
The most common one is spirometry, which measures how much air you can exhale and how fast. You’ll be asked to take a deep breath and blow out forcefully into a tube. The machine calculates metrics like FEV1 (forced expiratory volume in 1 second), which indicates how open your airways are.
Often, the test is repeated after giving a dose of a bronchodilator (like albuterol). If your lung function improves significantly with the medication, it suggests reversible airway narrowing, which is one of the main features of asthma.
Another test is bronchoprovocation (e.g., methacholine challenge), where you inhale a mist of a medication that can cause mild airway narrowing in sensitive lungs. If your lung function drops with a low dose of this agent, it confirms asthma because asthmatic airways react strongly to it. Doctors will also consider your symptom pattern and examine you for signs of asthma.
Now, because of the overlap, a comprehensive evaluation for someone who might have both often involves both kinds of testing. Guidelines for asthma management suggest that patients with persistent asthma be tested for allergies to help manage triggers.
Treatment and management of asthma vs. allergies
Because asthma and allergies are distinct conditions, they are often treated with different medications, but there is an overlap when it comes to allergic asthma.
Treating allergies
The primary goal is to reduce the immune reaction to allergens and relieve the specific symptoms:
Treating asthma
The focus here is to keep the airways open and non-inflamed:
Treating allergic asthma
Now, in allergic asthma, these two treatment approaches converge. A person with allergic asthma often needs both allergy treatments and asthma treatments.
They would avoid allergens and take antihistamines or nasal sprays as needed for allergy symptoms, and use inhalers for their asthma.
Some medications serve double-duty. As noted earlier, montelukast is a leukotriene blocker that can improve both allergic rhinitis and asthma control. It’s one pill a day that helps with both conditions by targeting a shared inflammatory pathway.
Allergy shots (immunotherapy), while traditionally used for allergies, have been shown to improve asthma as well. By making you less allergic, they remove or reduce one of the major triggers for your asthma. Over time, someone on allergy shots for, say, dust mite allergy might find they have fewer asthma attacks triggered by dust.
The biologic omalizumab (Xolair) we mentioned earlier is actually specifically indicated for moderate-to-severe allergic asthma. Blocking IgE helps prevent allergic reactions that set off asthma symptoms. This has improved control for many patients whose asthma was strongly linked to allergies.
Bottom Line
Understanding the difference between allergies and asthma matters because it ensures you get the right diagnosis and the right treatment, and it helps you take the right precautions.
If you have allergies and notice breathing issues like wheezing, frequent cough, or shortness of breath, you might have asthma that needs attention. Likewise, if you have asthma and are miserable every spring or whenever you pet a dog, you likely have an allergic trigger that you can do something about.
Both conditions are very treatable, especially now with advanced therapies. With proper management, most people with allergies, asthma, or both can lead full, active lives. The first step is recognizing each condition for what it is. With that knowledge, you can work with your healthcare providers to breathe easier and live better all year round.
Frequently Asked Questions
Sources
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What does asthma have to do with your allergies? Probably a lot. – ACAAI Patient. (2023, July 14). ACAAI Patient. https://acaai.org/resource/what-does-asthma-have-to-do-with-your-allergies-probably-a-lot/
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