Asthma-COPD overlap syndrome (ACOS) is when you have symptoms of both asthma and chronic obstructive pulmonary disease (COPD).

Asthma is a chronic lung disease that causes reversible airway narrowing, inflammation in the airways, and mucus production. Some symptoms of asthma are shortness of breath, tightening in the chest, and wheezing.

Most people with asthma have exacerbations, or flare-ups. These are times when their symptoms are worse than usual. There are also times when they have few or no symptoms.

Emphysema and chronic bronchitis are the two main conditions that fall under the COPD umbrella. COPD can cause shortness of breath, chest tightening, mucus production, and an ongoing cough. COPD is a progressive disease. People with COPD have regular symptoms and also experience flares.

Asthma and COPD are the most commonly diagnosed chronic lung diseases. They both involve inflammation of the airways, obstruction of airflow, and some other common symptoms.

Read on to learn more about asthma and COPD, and what it means to live with both conditions.

Symptoms of ACOS are likely to include:

  • labored breathing
  • wheezing
  • coughing, with or without mucus
  • tightness in the chest

Symptoms vary from day to day and typically includes flare-ups. There are also key differences between the symptoms of asthma and COPD.

If you only have asthma, symptoms change often and you can be symptom-free for a long time. Asthma often involves symptom triggers like exercise, exposure to allergens, or a respiratory illness. It can start in adulthood, but asthma usually begins in childhood. People with asthma often have allergies and the skin condition eczema.

If you only have COPD, symptoms usually start after age 40. Symptoms can vary from day to day, but they’re chronic and progressive, even with treatment. Most people with COPD also have a history of smoking or smoke exposure.

ACOS shares characteristics of both COPD and asthma. People with ACOS experience some type of ongoing airway obstruction.

They also experience wheezing, or breathing difficulties, that often respond to bronchodilators. Bronchodilators are medications that open the airway.

People with ACOS also seem to be younger and experience more shortness of breath than people with COPD alone. However, because this condition is still being studied, experts do not yet agree on a single way to define the syndrome.

Because ACOS means you have both asthma and COPD, it’s important to look at each condition.

Researchers don’t know exactly why some people develop asthma. You might be more likely to have it if you:

  • have a family history of allergies or asthma
  • you smoke or are regularly exposed to irritants such as tobacco smoke
  • have a personal history of allergies, especially if they developed in early childhood
  • had respiratory infections as a child

COPD is caused by long-term exposure to lung irritants. In the United States, the most common cause is cigarette smoke. Cigar smoke, pipe smoke, and secondhand smoke can cause COPD, too. So can chemical fumes, cooking fumes, and air pollution. Certain genetic mutations may make you more susceptible to COPD, but this is less common.

Having asthma doesn’t mean you’ll develop COPD. But children with severe, persistent asthma are 32 times more likely to develop COPD later in life.

ACOS has only recently been identified as a syndrome, so it’s not yet clear how many people are affected.

ACOS means you have symptoms of both asthma and COPD. Your doctor may diagnose asthma, COPD, or ACOS.

ACOS is a fairly new term. Exact guidelines for diagnosing ACOS haven’t been established. ACOS generally involves these three features compared with people who have COPD alone:

  • more of a response to inhaled bronchodilators
  • increased reversibility of airflow
  • bronchial and systemic inflammation from eosinophils, a type of white blood cell

To reach a diagnosis, your doctor will perform a physical examination and review your clinical history. Imaging tests such as X-ray, CT scans, or MRI may be necessary. It’s likely you’ll also need a noninvasive test called spirometry, also known as a pulmonary function test, to measure your lung function.

Because asthma causes inflammation, you’ll still need asthma treatment. This may include:

  • allergen avoidance
  • allergy medications
  • inhaled corticosteroids
  • short-acting bronchodilators
  • long-acting bronchodilators
  • preventive vaccines, such as flu, pneumonia, and whooping cough

You’ll also need to manage symptoms of COPD to maintain lung function. This may involve:

  • disease management training
  • pulmonary rehabilitation
  • avoiding smoke and other pollutants
  • healthy eating and nutrition education
  • long-acting bronchodilator combinations or combination bronchodilator or inhaled corticosteroids
  • preventive vaccines, such as flu, pneumonia, and whooping cough
  • oxygen therapy
  • surgery to remove damaged lung tissue or air sacs (bullae)

Treatment for ACOS will be tailored to your symptoms and preferences. ACOS requires careful management and adherence to therapy. These are some of the people you might have on your healthcare team:

  • doctors
  • nurses
  • respiratory therapist
  • physical therapist or exercise expert
  • dietitian or nutritionist

Check out: COPD and allergies, avoiding pollutants and allergens »

After a diagnosis of ACOS, your doctor will instruct you on how best to manage your condition. Take medication as prescribed and follow up regularly.

Here are some other tips for managing ACOS:

  • Maintain a healthy diet. Eating well can help you keep up your strength and improve your health. Ask your doctor if you have nutritional requirements and if you should take dietary supplements. Consider working with a dietician or nutritionist.
  • Get vaccinated. Additional respiratory illnesses can become dangerous. To lower your risk of contracting influenza, pneumonia, and whooping cough, talk to your doctor about vaccinations for these and other illnesses.
  • Avoid smoke and other pollutants that can irritate your lungs and make symptoms worse.
  • Exercise. Physical activity is important to your health. But you don’t want to overdo it either. Consult your doctor so you know what activities are safe for you. Ask your doctor about pulmonary rehabilitation and other exercise programs for people with lung disease.
  • Seek support. Whether it’s friends and family, psychological counseling, or a support group, it’s important to reach out for support. Also make sure those closest to you know about your condition and what to do in an emergency.

For more information about support groups, check out the American Lung Association Better Breather's Club.

Always contact your doctor if you experience sudden worsening of symptoms, fever, or if you feel ill.

Learn more: 6 tips for running with exercise-induced asthma (EIA) »

There’s no cure for ACOS. According to a 2015 systemic review and meta analysis, people with ACOS tend to have more hospitalizations, higher healthcare costs, and poorer quality of life than those who have only asthma or COPD.

ACOS is chronic and progressive, meaning it worsens over time. Treatment and disease management can help keep symptoms under control.

Your doctor can offer more detailed outlook information based on your age, symptoms, and overall health.

Keep reading: 5 diet tips for people with COPD »

As far as researchers know, there is no way to prevent asthma, but you can lower your risk of developing COPD. It’s unclear if lowering your risk of COPD also lowers your risk of developing ACOS.

If you have asthma, you may be more susceptible to developing COPD if your asthma is severe and persistent. Managing your asthma is the best way to minimize the disease process. See your doctor regularly, avoid smoke and other lung irritants, and take prescribed medications as directed. Quitting smoking as soon as possible is key.

Smoking is the leading cause of COPD, and it makes asthma more difficult to manage. It can also harm the health of those around you. If you can’t quit smoking on your own, talk to your doctor about smoking cessation programs. Or check out the American Lung Association Freedom from Smoking program or call the Lung HelpLine at 1-800-LUNGUSA.