Often, treatments developed for asthma can be used for chronic obstructive pulmonary disease (COPD), and treatments used for COPD can be used for asthma—because asthma and COPD are two different diseases, although, with similar symptoms, this may seem a bit perplexing. However, researchers have determined that these two lung diseases have many aspects in common.
Asthma and COPD remain two separate diseases with distinct characteristics and approaches to treatment, but an understanding of both diseases has helped us further our understanding.
Defining Asthma and COPD: Similarities and Differences
Airway obstruction occurs in both asthma and COPD —often the main differential difference is the age of diagnosis. COPD most often occurs in those older than age 40; however, asthma can also be diagnosed in those older than 40 years old.  Most often those with COPD are diagnosed later in life and have a history of smoking, but may also have a history of chemical exposure or other lung damage inducing compounds at work—this is a known cause of COPD.  Most cases of COPD may be preventable by avoiding smoking or other irritant exposures, although genetics may also play a role in determining who develops COPD and who doesn’t.  Asthma, on the other hand, may be caused by genetic factors and/or environmental factors, but its cause is not well determined.  While both conditions are treatable with medications, asthma tends to be controllable with medications, and when treated, lung function remains stable over time and improves with bronchodilators.
In COPD, lung damage is irreversible, and the disease progresses (gets worse) over time. While bronchodilator medicines that open the airways are helpful in both diseases, airway obstruction is only fully reversible in asthma.  Another major difference are the causes of daily symptoms between asthma and COPD.
Major Difference: Triggers
A major difference between triggers of COPD and asthma exacerbations, also known as “flare-ups”. Asthma attacks or exacerbations are triggered by a variety of allergic and non-allergic triggers, including cold air, exercise, allergens like dust, mold, pollen, and animal dander, as well as viruses and infections.  In COPD, most flare-ups are caused by respiratory tract infections like colds, viruses, and flu, which may occur more frequently in COPD due to germs getting "stuck" in the mucus, and cyclic nature of infection due to difficulty clearing the mucus due to airway damage. 
Major Difference: Treatment
Despite similarities in medications for COPD and asthma, the front line treatments are opposites. Asthma is first treated with an inhaled corticosteroid (ICS), where COPD treatment begins with long-acting bronchodilators.  COPD may be treated with an ICS and long-acting bronchodilator, but this is only in severe cases with significant inflammation.  Airway damage and remodeling is a greater issue in COPD, requiring the use of bronchodilator medications, or at times, multiple bronchodilator medications of different types, often in combination inhalers. 
Asthma-COPD Overlap Syndrome (ACOS)
A study in CHEST found 15% of patients diagnosed with COPD also met diagnostic criteria for asthma, indicating Asthma-COPD Overlap Syndrome (ACOS) in which characteristics of both diseases are present. Other studies indicate rates of asthma in those with COPD could be as high as 40%.  Patients with ACOS respond well to bronchodilators had high eosinophils or IgE (indicating eosinophilic disease or allergic disease; not common features of COPD).  While ACOS may sound like a new term, it’s not a new phenomena—because of the similarities between asthma and COPD including pulmonary function decreases, response to medications, and presence of inflammation, it has always been challenging to differentiate some cases of asthma from COPD, however, acknowledging potential coexistence is where ACOS comes into play as a diagnosis. 
Given the difference between asthma and COPD, and that they can exist in concert, it is important for your doctor to come to an accurate diagnosis and treat your asthma, COPD or ACOS appropriately. Staying in regular contact with your doctor can help ensure you are kept up to date on new treatment options for whatever condition you have.
Information on this page is for reference and educational purposes only. For more information about COPD and asthma, talk to your doctor or primary care provider.
Page last updated: October 29, 2018
 Healthline. Asthma vs. COPD: How to tell the difference? https://www.healthline.com/health/copd/asthma#triggers
 S. Sethi. Infection as a comorbidity of COPD. http://erj.ersjournals.com/content/35/6/1209
 Hardin, M. & Silverman, E. Chronic Obstructive Pulmonary Disease Genetics: A Review of the Past and a Look into the Future. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5559139/
 Cosio et al. Defining the Asthma-COPD Overlap Syndrome in a COPD Cohort. http://es.ereprints.elsevier.cc/9PB6024/abstract
 Murphy, A. Knowing the differences between COPD and asthma is vital to good practice. https://www.pharmaceutical-journal.com/learning/learning-article/knowing-the-differences-between-copd-and-asthma-is-vital-to-good-practice/11085597.article?firstPass=false
 National Jewish Health. Bronchodilators. https://www.nationaljewish.org/treatment-programs/medications/copd/bronchodilators