Asthma vs. COPD: What's the Difference?

Asthma and chronic obstructive pulmonary disease (COPD) are lung diseases. Both cause swelling in your airways that makes it hard to breathe.

With asthma, this swelling is often triggered by something you’re allergic to, like pollen or mold, or by physical activity. COPD is the name given to a group of lung diseases that include emphysema and chronic bronchitis.

Emphysema happens when the tiny sacs in your lungs (called alveoli) are damaged. Chronic bronchitis is when the tubes that carry air to your lungs (bronchial tubes) get inflamed. Smoking is the most common cause of those conditions (and COPD).

Some people have asthma and COPD at the same time. If you have symptoms of both diseases, your doctor may call it asthma-COPD overlap syndrome.

Who’s Likely to Have Asthma or COPD?

People who smoke or breathe in pollution or chemicals at work for many years have higher chances of having COPD. That's why the condition often starts in middle age or later in life.

Asthma is sometimes caused by gene changes that are passed down through families. If one of your parents has the disease, you're more likely to have it. Symptoms often start in childhood.

A few other things can also raise your chances of asthma:

  • Allergies
  • Lung infections
  • Smoking
  • Being around chemicals or other irritants in the air

Symptoms

Since asthma and COPD both make your airways swell, they both can cause:

One main difference is that asthma typically causes attacks of wheezing and tightness in your chest. COPD symptoms are usually more constant and can include a cough that brings up phlegm.

Diagnosis

To figure out which condition you have, your doctor will start with a physical exam and questions about your medical history. They’ll look at your nose and throat and listen to your lungs with a stethoscope. Questions they’re likely to ask include:

  • What symptoms you've had
  • If you have a family history of asthma or allergies
  • If you smoke or are around secondhand smoke
  • If you work around chemicals or other things that can irritate your lungs

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Your doctor will also want to do a test called spirometry that checks how well your lungs work. You’ll blow into a mouthpiece and a machine will measure how much air you can blow out and how fast you can do it.

If your doctor thinks you have asthma, they might ask you to breathe in a medicine called a bronchodilator and take the spirometry test again. If you have asthma, your lungs should work better after you take the medicine.

Another way to diagnose asthma is with a challenge test. You breathe in an asthma trigger like a strong scent or the drug methacholine. Then you take a spirometry test to see if your airways have narrowed. Weaker airflow afterward can be a sign that you have asthma.

Tests used to diagnose COPD may also include:

  • Chest X-ray: This uses radiation in low doses to make images of your lungs.
  • Arterial blood gas test: This measures how much oxygen is in your blood. COPD can make your blood oxygen level drop.

Treatment

With asthma, symptoms come and go in the form of attacks. For some people, these may happen more often or be more serious over time, but that’s not the case for everyone.

Asthma medicines come in two types. Quick-relief medicines relax your airways to let more air into your lungs. You take them when you have an asthma attack to quickly stop wheezing and other symptoms.

  • Short-acting beta-agonists relax the muscles around your airways.
  • Anticholinergics both relax your airways and reduce the amount of mucus in your lungs.

Long-term medicines help keep asthma symptoms at bay. You take these medicines every day.

  • Corticosteroids bring down swelling in your lungs. You breathe in the medicine through a device called an inhaler or take them as pills.
  • Inhaled long-acting beta-agonists relax the muscles around your airways to help you breathe more easily. These are always used along with other asthma medications.
  • Other anti-inflammatory drugs, such as cromolyn, help keep your airways from swelling up.
  • Leukotrine modifiers are pills or liquids that block the process that causes airway swelling.
  • Immunomodulators work directly on the immune system. These are also called biologics.
  • Theophylline helps open your airways.
  • Allergy shots or sublingual tablets are two types of immunotherapy that may help if your asthma is triggered by allergies.

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COPD causes daily symptoms that get worse over time. Following a treatment plan can slow this down and help your lungs work better longer. COPD is treated with some of the same medicines as asthma, while others are different.

  • Bronchodilators relax the muscles of your airways.
  • Corticosteroids ease swelling inside your airways.
  • Phosphodiesterase-4 (PDE4) inhibitors bring down swelling in your lungs to prevent COPD flare-ups.
  • Antibiotics treat infections that can make your COPD symptoms worse.

A few nondrug treatments can also help control COPD symptoms.

  • Pulmonary rehabilitation. This program teaches you exercises and suggests changes in your diet and other tips to help you live better with COPD.
  • Supplemental oxygen. If your lungs can't pull enough oxygen into your blood, you may need to breathe in oxygen from a tank or machine.
  • Surgery. Removing the damaged areas of your lungs can sometimes help the healthy parts work better.

Whether you have COPD or asthma, it's important to stop smoking. It’s also best to stay away from anything that irritates your lungs, such as:

  • Spray chemicals like cleaning products and bug killers
  • Allergens like mold, dust, and pollen
  • Perfumes and other scents
  • Secondhand smoke
WebMD Medical Reference Reviewed by Melinda Ratini, DO, MS on October 16, 2018

Sources

SOURCES:

American Academy of Allergy, Asthma & Immunology: "Asthma and COPD: Differences and Similarities," “Asthma Definition,” "Chronic Obstructive Pulmonary Disease (COPD)."

American Academy of Family Physicians: "COPD and Asthma: Differential Diagnosis."

American College of Allergy, Asthma & Immunology: "Asthma Information."

American Lung Association: "How is COPD Diagnosed?" "Oxygen Therapy," "Surgery for COPD." "The Basics of Pulmonary Rehabilitation," "The Link Between Asthma & COPD," "What Causes Asthma?" "What Causes COPD."

Asthma & Allergy Foundation of America: "Asthma Diagnosis," "Asthma Treatment," "Provocation (Trigger) Tests," "Spirometry."

Breathe New Hampshire: "How is COPD Diagnosed?"

Cleveland Clinic: "Chronic Obstructive Pulmonary Disease (COPD)," "Chronic Obstructive Pulmonary Disease (COPD): Management and Treatment."

COPD Foundation: "COPD Treatments."

Materia Sociomedica: "Asthma and chronic obstructive pulmonary disease (COPD)--Differences and Similarities."

Mayo Clinic: "Asthma: Steps in Testing and Diagnosis," “Bronchitis,” "COPD," “Emphysema.”

National Heart, Lung, and Blood Institute: "Asthma," "Asthma Care Quick Reference."

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