Diagnosing Asthma

Asthma is a common and unfortunately chronic condition, characterized by airway inflammation (swelling), increased mucus in the airways, and constriction of the muscles lining the airways (bronchospasm). These result in the classic asthma symptoms of coughing, wheezing, and shortness of breath or chest tightness. Some people with asthma cough more than they wheeze, some just complain of shortness of breath, especially with activities.

Asthma comes in different shapes and sizes, some people have allergic airway inflammation, and others don’t. Some young children have a kind of asthma that only happens with viral infections, often outgrowing this by school age, others have associated food allergies or eczema and are more likely to have asthma into their adult life.


Not all asthmatics wheeze, and not all wheezing is asthma. In children, the dominant symptom of asthma is coughing. Coughing during the night, with activities, in cold air, and after laughing or crying are warning signs. Children with asthma will commonly cough to the point of gagging or vomiting, a fairly uncommon occurrence otherwise, but also noted with pertussis or whooping cough.

That said, there are lots of other reasons people may cough. One of the most common is upper airway cough syndrome, which we often call postnasal drip. People with upper airway cough will typically cough more when they lie down or wake up, but not as much while asleep, unlike asthma which will often wake sufferers from their sleep. Although kids with upper airway cough may cough more with activities, this does not usually slow them down, and they often keep playing happily despite the coughing that may worry their parents more than them! Children with asthma will freely admit they have trouble keeping up with their friends, often to their frustration.

Wheezing can be a tricky symptom, because not all noisy breathing is true wheezing. It is important to try to determine if the noise is more prominent on the breath in or the breath out. True wheezing is typically on exhalation (the breath out), and asthmatics often have a prolonged expiratory phase, meaning it takes quite a bit longer to empty the lungs. Noises on the breath in are called “stridor” and are typical of croup or other upper airway problems rather than asthma.
Even shortness of breath can be hard to sort through. Lots of people, especially young competitive athletes or adult women, complain of difficulty getting their breath and noisy breathing caused by vocal cord dysfunction rather than asthma, although most are misdiagnosed with asthma and treated for asthma, often for years before the proper diagnosis is made.


In older children or adults, it is essential to have lung function testing to help support or confirm a suspected asthma diagnosis. Breathing tests may not be able to “rule out” a diagnosis of asthma, but coupled with the clinical history, these can go a long way to sorting this out for most patients.
In children under age 6, it is difficult to perform lung function testing, and the diagnosis rests on careful and repeated history taking, and therapeutic trials. If a child has recurrent or persistent coughing or wheezing, and shows a clear consistent response to inhaled asthma medications, then they almost certainly have asthma. Asthma medications don’t treat pneumonia or “bronchitis”, and infants with viral bronchiolitis (a specific syndrome in children usually <18 months of age) do not respond to asthma medications. If they do, it’s because they actually have asthma instead. Often doctors are reluctant to use the word “asthma” in very young children, often using vague and unhelpful terms such as “reactive airways” or “wheezy bronchitis” instead. Unfortunately, this all-too-common practice doesn’t help, because studies show that delays to proper diagnosis and appropriate long-term treatment plans lead to permanent irreversible changes to the airways even in very young children, and we must work hard to ensure this isn’t happening in this day and age.

One of the points we try to emphasize is that our goal for asthma management is the same as the patient’s or parents, the least amount of medication that adequately controls the asthma. But as I am also very fond of saying, we don’t decide how much medication that is, nor does the patient or parent, the asthma gets final say. We try to reassure people that current asthma medications have an excellent safety profile, even in the long-term, and that it is quite safe and appropriate to undergo a trial of therapy to help confirm or refute the suspected asthma diagnosis, often it is the only way to do so accurately, especially in younger children.
It is also important to realize that for every person we see with uncontrolled or under-treated asthma, we see one who is being treated for asthma they really don’t have. It again comes down to the importance of an accurate diagnosis, which always has to be our primary focus.