What Is Asthma-COPD Overlap?

Asthma-COPD overlap (ACO), which used to be called asthma-COPD overlap syndrome, happens when you have symptoms of both asthma and chronic obstructive pulmonary disease (COPD). The main thing these two lung problems have in common is that they make breathing difficult. But in other ways, they're different.

For example, asthma gets better. Symptoms can come and go, and you may be symptom-free for a long time. With COPD, symptoms are constant and get worse over time, even with treatment. And the diseases are caused by different things.

It's possible to have symptoms of both asthma and COPD, and some researchers think the two conditions could be more closely related. ACO isn't a separate disease. The name is a way to acknowledge the mix of symptoms.

It's important to find and treat ACO because it can be more serious than having either condition alone. There's no cure, but you and your doctor can work together to help you breathe and live better.


Asthma and COPD, and therefore ACO, make it harder to move air in and out of the airways in your lungs. This often happens because your airways are more narrow than normal -- inflamed or blocked by mucus.

You usually get asthma because of allergies. Your lungs react to things that don't bother most people, like cat hair, dust, exercise, or even laughing.

COPD is mainly caused by breathing fumes that irritate your lungs. The most common is tobacco smoke. But COPD can also come from air pollution or toxins at work. Having asthma when you're young raises your chance of COPD, too.

When you have COPD, your airways may get less elastic or stretchy over time. This also makes it tough to push air out and fully empty your lungs. One result is you don't take in as much oxygen as you need. Another is that the waste product carbon dioxide builds up. Too much carbon dioxide left in your body can make you feel weak.

It's not clear what causes ACO. Having COPD for a long time may change the way your lungs work and make you more likely to get it. Or it might start if you smoke while you have asthma. It may also happen for reasons no one has figured out yet.



People who get ACO tend to be over 40 but younger than people with just COPD, and they have allergies (or have family members with them). Symptoms vary but commonly include:

You'll have more symptoms than with either asthma or COPD alone, and you'll have more severe attacks more often. You'll end up in the hospital more. But someone with ACO may have a better chance of survival than with only COPD.


There's no widely accepted, clear-cut definition of what ACO is, so your doctor will look at several pieces of the puzzle.

They'll ask about your medical history, including when your symptoms started and how they've changed over time, and do a complete physical exam. You might have a chest X-ray or CT scan to look at your lungs.

You'll also probably have a test called spirometry. It's one of the most common ways to understand how your lungs work. It's painless and easy. All you have to do is blow into a tube. The test measures how much air you can take in and how much and how fast you can blow out.

Your doctor might check how well your lungs work before and after you use inhaled medicine, like a rescue inhaler. Blood tests can look for higher levels of inflammation.

If you have a fairly even mix of traits from both asthma and COPD, you may have ACO.


Because studies for each disease usually excluded people who had features of the other -- asthma studies didn't allow smokers, and COPD studies didn't include nonsmokers or people who got better using a bronchodilator -- we aren't sure how best to treat ACO.


Your doctor may start you on a low-dose inhaled corticosteroid. This is the most common long-term control medicine for asthma. It helps treat chronic symptoms and prevents asthma attacks.

You may also need a long-acting bronchodilator, typically a medicine called a beta-agonist (LABA). This keeps your airways open for 12-24 hours, but it shouldn't be the only medicine you use for ACO.

Sometimes your doctor may add another medicine called a long-acting muscarinic agonist (LAMA). It helps keep airways from tightening and making too much mucus.

Do Your Part

Quit smoking if you haven't already. Avoid smoke and other things that can irritate your lungs.

Exercise. When you hear that, you probably think, "Not me. No way." But exercise keeps your lungs strong and helps you stay fit.

Talk to your doctor about pulmonary rehab. It's a special program where you learn to exercise with less shortness of breath. It can help you be more active in the rest of your life, too.

Breathing takes more energy when you have ACO. Eating right won't cure ACO, but it can make you feel better.

To keep feeling strong, choose fruits, vegetables, whole grains, and healthy fats like olive oil. Avoid foods that cause bloating like beans, broccoli, corn, soda, and fried, greasy, or spicy foods. They can make it even harder to breathe.

WebMD Medical Reference Reviewed by Carol DerSarkissian on June 13, 2020


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