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Asthma-COPD Overlap Syndrome (ACOS)

Is It Asthma, COPD or Both?

Both asthma and chronic obstructive pulmonary disease (COPD), including emphysema and chronic bronchitis, make breathing difficult. In fact, they share many similarities. However, they are different lung diseases. Asthma-COPD overlap syndrome (ACOS) is diagnosed when you have symptoms of both asthma and COPD. ACOS is not a separate disease, but rather a way for doctors to recognize the mix of symptoms and select a treatment plan that is most appropriate for you.

Symptoms of ACOS

People diagnosed with ACOS typically experience symptoms more frequently than people with asthma or COPD alone and have reduced lung function. Symptoms include:

  • Difficulty breathing
  • Excess mucus (more than usual)
  • Feeling tired
  • Frequent coughing
  • Frequent shortness of breath
  • Wheezing

If you have asthma or COPD, it may be difficult to tell the difference between these two chronic lung diseases, especially as people living with asthma or COPD get older or smoke. People with a diagnosis of ACOS tend to have more symptoms than people with either asthma or COPD alone and have more severe attacks, leading to more emergency room visits and hospitalizations. It is important to find out if you have ACOS because it can be more serious than having either asthma or COPD alone. While there is no cure for either disease, your doctor can monitor your health and adjust your medicines to help you breathe better.

Diagnosing ACOS

Doctors are still trying to understand when asthma and COPD overlap. "Persistent airflow obstruction with features of asthma" is how they define this disease. Your doctor will gather a detailed medical history, perform a physical exam and may order a chest X-ray or CT scan. Also, your doctor may use a form to ask a series of questions to help them determine if its asthma, COPD or ACOS.

Some of the measures that your doctor will look at to make a diagnosis include:

  • Age of onset
  • Pattern of respiratory symptoms
  • Lung function
  • Past history or family history
  • Chest X-ray
  • Episodes or flare-ups
  • Airway inflammation
  • Smoking
  • History of exposure to lung irritants

Treatment Options

There is not a single medicine that can improve ACOS, but there are three types of medicines available today that can help improve symptoms. These include:

  • Low-dose inhaled corticosteroid (ICS)
    A common long-term control medicine for asthma that treats the ongoing inflammation in the airways.
  • Long-acting bronchodilator (LABA)
    A long-term control medicine for asthma that keeps the airways open for a longer period of time (12-24 hours). This type of medicine should not be used alone and should be combined with another medication that treats inflammation.
  • Long-acting muscarinic agonist (LAMA)
    A common medicine used to treat COPD symptoms. It helps keep airways from tightening and making too much mucus.

Take Action

Don't make excuses. If you are short of breath, have chest tightness or cough that won’t go away, make a visit to your doctor and tell them all about it.


    Reviewed and approved by the American Lung Association Scientific and Medical Editorial Review Panel. Last reviewed April 29, 2019.

    Page Last Updated: April 29, 2019

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