Two overlapping pairs of lungs.

What is Asthma?

Last updated: August 2019

Asthma is a chronic lung disease like COPD. Its symptoms can certainly mimic COPD. In fact, some people with COPD also have asthma. But, asthma is not COPD. So, what is asthma anyway? Here’s what to know.

Here are some key features of asthma:

Inflamed airways

The main feature of asthma is underlying airway inflammation. It’s chronic, meaning it’s always there to some degree. There is also inflammation in COPD, but it’s a different kind of inflammation. Asthmatic inflammation responds very well to corticosteroids.

Asthma triggers

These are things that are harmless to most people. But, to asthmatics, they trigger asthma attacks. They include allergens like dust mites and mold spores. They include irritants like cigarette smoke and strong smells. So, this is also similar to COPD.

Abnormal immune response

Asthma is a disease of an abnormal immune response. Exposure to asthma triggers causes an abnormal immune response that worsens the underlying airway inflammation. This inflammation irritates airway cells. This irritation is what causes asthma symptoms.

Airway smooth muscle cells are easily irritated

They are wrapped around airways. Worsening inflammation causes them to spasm. They tighten and hug airways nice and tight. This makes airways narrow. This causes airways to become obstructed. This causes chest tightness and shortness of breath.

Goblet cells are easily irritated

They secrete mucus. It’s a sticky substance that traps pathogens. It helps to keep your airways germ free. But, worsening airway inflammation irritates these cells. This causes them to secrete excessive mucus. This can further obstruct airways. It can cause symptoms like chest tightness and coughing.

Airways become obstructed

This is also similar to COPD. Obstructed airways let air in but won’t let air back out so easily. Exhaled air is said to be slowed by the obstruction. Another term for this is airflow limitation.

Airflow limitation

It’s the medical term for when an airway obstruction slows the flow of exhaled air. It makes you feel short of breath. If it's always present to some degree, you have COPD. If it is reversible with time or treatment, you probably have asthma. A good way to help doctors diagnose one or the other is by having you perform a PFT.

Pulmonary Function Test (PFT)

It’s a test to measure lung function. You breathe into a mouthpiece. You inhale as deep as you can and exhale as fast as you can until your lungs are completely empty. A computer can measure if you have airflow limitation. You are then given an albuterol breathing treatment. A repeat test will show if airflow limitation is reversed. If your lung function improves after the treatment you may have asthma. This is because a key part of the asthma definition is that it is a reversible disease.


Asthma symptoms are completely or almost completely reversible with time or treatment. This means that breathing is easy between asthma attacks. So, another characteristic of asthma is that it's intermittent.


Asthma attacks occur once in a while, and usually when exposed to some asthma trigger. Between asthma attacks, breathing is normal or close to normal. Lung function is also normal or close to normal. This is contrary to COPD, where some degree of symptoms occurs even on good COPD days.


This means asthma attacks are rare and easy to control when they do occur. This can be accomplished by working with an asthma doctor and creating an asthma treatment regimen. Such a regimen may include controlling your asthma triggers. It may also include taking asthma controller medicines every day. In a way, this is similar to how COPD is controlled.


Many of the same medicines used to treat COPD are used to treat asthma. Asthmatic inflammation responds well to inhaled corticosteroids like Flovent. It also responds well to beta-agonists like albuterol. Common asthma controller medicines include Advair and Symbicort. Like COPD, controlling asthma also entails avoiding those things that trigger it.


This means that you have two diseases together. Some people with COPD also have asthma. So, treating one means treating the other. Some people with both conditions may be diagnosed with Asthma/ COPD Overlap.

What to make of this?

So, there are definitely some similarities between COPD and asthma. But they are two unique diseases with unique (but similar) treatment strategies.

By providing your email address, you are agreeing to our privacy policy.

This article represents the opinions, thoughts, and experiences of the author; none of this content has been paid for by any advertiser. The team does not recommend or endorse any products or treatments discussed herein. Learn more about how we maintain editorial integrity here.

Join the conversation

Please read our rules before commenting.

Community Poll

Does your COPD make running errands more difficult?