Asthma is a chronic airway condition that can make breathing feel difficult, tight, or unpredictable. Because symptoms vary widely and may come and go, many patients wonder how asthma is diagnosed and whether testing will clearly confirm it.
With guidance from Dr. Shashank S. Sheth, an adult and pediatric allergy, asthma, and immunology specialist, this guide explains how asthma is evaluated in children and adults. We’ll review the symptoms that prompt testing, the breathing tests used to support a diagnosis, and how providers rule out other conditions to ensure an accurate diagnosis.
Why Diagnosing Asthma Can Be Challenging
An asthma diagnosis can often be challenging because asthma does not look the same in everyone. “Asthma can present with a wide degree of symptoms. There is often a misconception that one must have wheezing or labored breathing to have a diagnosis of asthma. Asthma symptoms include shortness of breath, chest tightness, wheezing, or cough.” Dr. Sheth explains.
Another challenge is that asthma symptoms may not be present during a doctor’s visit. Many patients feel well between flare-ups, which can make testing appear normal at certain times.
Because of this variability:
- No single test alone confirms asthma
- Diagnosis combines symptoms, medical history, and objective testing
- Some tests may need to be repeated over time
Common Symptoms That Lead to Asthma Testing
Asthma testing is often recommended when symptoms are recurrent, persistent, or triggered by specific exposures or activities.
Common symptoms include:¹
- Shortness of breath
- Chest tightness or pressure
- Wheezing
- Symptoms that worsen at night or early morning
- Breathing difficulty with exercise, cold air, or allergens
- Cough that lingers or returns frequently
Coughing is a symptom of asthma that is often overlooked. “There is often a misunderstanding that a cough and asthma are not related. Many times, asthma presents with a cough that can vary in intensity and frequency,” says Dr. Sheth. A chronic cough, especially one that worsens at night or with activity, can be a key sign of asthma, even in the absence of wheezing.
Medical History and Physical Exam
The diagnostic process usually begins with a detailed medical history and physical examination. Your provider will ask about:¹
- The type, frequency, and duration of symptoms
- Triggers such as exercise, allergies, infections, or irritants
- Family history of asthma or allergies
- Past respiratory illnesses
- Environmental or workplace exposures
A physical exam focuses on listening to your lungs and checking for signs of nasal inflammation, allergies, or other conditions that may affect breathing. This step helps guide which tests are most appropriate and whether other diagnoses should be considered.
Breathing Tests Used to Diagnose Asthma
Pulmonary function tests (PFTs) are a core part of asthma diagnosis. These tests measure how well air moves in and out of your lungs.
Bronchodilator Response Testing
If spirometry shows reduced airflow, you may repeat the test after using a bronchodilator inhaler. This medication relaxes airway muscles.
Improvement after bronchodilator use suggests reversible airway narrowing, a hallmark of asthma. This response strengthens confidence in the diagnosis.²
Spirometry Test
Spirometry is the most commonly used asthma test. It measures:
- How much air you can exhale
- How fast you can exhale
- Whether airflow is reduced
You’ll be asked to take a deep breath and blow forcefully into a mouthpiece. Results are compared to expected values based on age, height, and sex. Spirometry can identify airflow obstruction consistent with asthma, even if symptoms feel mild.²
Peak Flow Measurement
Peak flow testing measures how quickly you can exhale air. While less detailed than spirometry, it can be useful for:
- Monitoring asthma over time
- Identifying variability in airflow
- Detecting worsening control
Some patients use peak flow meters at home to track symptoms between visits.²
Challenge Tests for Asthma Diagnosis
When spirometry is normal but asthma is still suspected, challenge tests may be used to provoke airway narrowing in a controlled setting.
Methacholine Challenge Test
Methacholine is an inhaled substance that causes airway narrowing in people with asthma. During this test:
- Increasing doses are inhaled
- Lung function is measured after each dose
- A drop in airflow suggests airway hyperreactivity
A negative test makes asthma less likely, while a positive test supports the diagnosis.³
Exercise Challenge Test
This test evaluates for exercise-induced asthma (also called exercise-induced bronchoconstriction). Lung function is measured before and after physical activity.
It’s especially helpful for patients whose symptoms mainly occur during or after exercise.³
Allergy Testing and Asthma
Many people with asthma also have allergies. Allergy testing helps determine whether allergens are contributing to airway inflammation.¹
Testing may identify sensitivity to:
- Pollen
- Dust mites
- Mold
- Pet dander
Allergic asthma involves immune responses that trigger airway narrowing, while non-allergic asthma is triggered by factors such as infections, cold air, or irritants. Identifying allergic triggers allows for more targeted treatment.
Imaging and Additional Tests to Rule Out Other Conditions
Asthma symptoms can overlap with other conditions, so additional testing may be used to rule out alternative causes.
These tests may include:
- Chest X-ray
- Sinus imaging
- Acid reflux evaluation
- Vocal cord assessment
The goal is not to confirm asthma alone, but to ensure symptoms are not caused by another underlying condition.
Diagnosing Asthma in Children vs. Adults
Asthma diagnosis differs by age.
Childhood Asthma Diagnosis
Asthma in children often presents differently than in adults, and diagnosis may rely more heavily on clinical patterns and observation. Important considerations include:⁴
- Symptoms may be triggered by viral infections
- Testing can be limited in very young children
- Diagnosis often relies more heavily on symptom patterns and response to treatment
Adult Asthma Diagnosis
Adult asthma can resemble other conditions, making objective testing especially important. Key factors include:
- New-onset asthma can occur later in life
- Symptoms may be mistaken for heart or another lung disease
- Objective testing is usually more reliable
Adult asthma is commonly underdiagnosed, especially when symptoms are subtle or attributed to aging or fitness changes.
Conditions That Can Mimic Asthma
Several conditions can cause symptoms similar to asthma, including:⁵
- Chronic obstructive pulmonary disease (COPD)
- Vocal cord dysfunction
- Chronic sinus injections
- Acid reflux
- Heart conditions
- Chronic bronchitis
Distinguishing asthma from these conditions is a key reason why proper testing and specialist evaluation matter.
When to See a Specialist for Asthma Testing
If you’re having symptoms, it’s worth seeing a specialist. “There have been several advances in therapies for asthma in recent years, which are safer for short-term and long-term treatment,” Dr. Sheth explains. An asthma diagnosis can have an impact on your quality of life.
Seeing a specialist is recommended if:
- Symptoms persist despite basic treatment
- You have frequent flare-ups
- Breathing issues interfere with sleep or activity
- Diagnosis remains unclear
- You experience chronic coughing without explanation
What Happens After an Asthma Diagnosis
After diagnosis, treatment focuses on:¹
- Reducing airway inflammation
- Preventing flare-ups
- Relieving symptoms quickly when they occur
Management often includes:¹
- Inhaled medications
- Trigger avoidance strategies
- Ongoing monitoring
- Periodic lung function testing
Modern asthma therapies are more targeted than in the past, allowing effective control with fewer side effects.
Frequently Asked Questions
Can asthma tests be normal between flare-ups?
Yes. Asthma symptoms and airflow limitation can come and go, which means tests may appear normal when symptoms are inactive.
Can asthma develop in adulthood?
Yes. Dr. Sheth explains that “asthma is often thought to be a childhood or long-term condition; however, many people can have new onset asthma in their 40s, 50s and beyond.”
Can allergies cause asthma symptoms?
Yes. Allergies can trigger airway inflammation and worsen asthma symptoms in people with allergic asthma.¹
How long does it take to diagnose asthma?
Diagnosis may occur in one visit or over several visits, depending on symptom patterns and test results.
Can asthma be misdiagnosed as something else?
Yes. Several conditions mimic asthma, which is why thorough testing and follow-up are important.⁵
Schedule an Asthma Evaluation Near You
If you’re experiencing ongoing breathing symptoms, chronic coughing, or unexplained shortness of breath, an evaluation with a specialist can provide clarity and direction. Our board-certified allergy, asthma, and immunology physicians serve patients across New York, New Jersey, Pennsylvania, and Texas, offering comprehensive testing and personalized treatment plans.
A structured diagnostic approach helps ensure the right diagnosis—and the right treatment—so you can breathe more comfortably and confidently. Schedule your appointment online today to connect with an asthma specialist near you.
Sources:
MedlinePlus. Asthma.
Asthma and Allergy Foundation of America. Lung Function Tests.
Asthma and Allergy Foundation of America. Provocation (Trigger) Tests.
MedlinePlus. Asthma in Children.
Asthma and Allergy Foundation of America. Asthma-Like Conditions.