15 Reasons You're Short of Breath

Here's how to tell whether your shortness of breath is due to exercise or something more serious.

Shortness of breath can be uncomfortable, even stressful, to experience. The feeling that you're not getting enough air can come on suddenly whether you are active or sedentary.

It's normal for strenuous exercise, temperature changes, poor air quality, high altitude, and obesity to make breathing difficult. But if your breathing suddenly changes for no reason you can identify, your shortness of breath may indicate a health condition.

Shortness of breath can be caused by something as simple as exercise to more severe issues like pneumonia, asthma, and even heart failure or lung cancer. Here are 15 reasons why you may be experiencing shortness of breath.


Shortness of breath is one of the hallmark symptoms of asthma—caused by narrow airways, making it harder for air to travel naturally in and out of your body. Other symptoms of asthma include:

  • Wheezing
  • Coughing
  • Chest tightness

There are two main types of asthma: allergic and non-allergic, each with very different causes and treatments.

Exposure to certain allergens such as cigarette smoke, pollen, pet dander, dust mites, mold, and even weather elements triggers allergic asthma. It's relatively easy to manage with medications.

On the other hand, non-allergic asthma is mysterious, harder to treat than allergic asthma, and tends to strike people who are middle-aged or overweight, said Norman Edelman, MD, senior scientific advisor for the American Lung Association. However, it's not clear if losing weight helps alleviate non-allergic asthma.

Many people don't realize you can develop asthma not only in childhood but also as an adult. In both cases, it tends to be chronic.


Like asthma, chronic obstructive pulmonary disease (COPD) involves constricted airways that cause not just shortness of breath but also wheezing, chest tightness, and a cough with mucus. Other symptoms of COPD include:

  • Wheezing
  • Cough with mucus
  • Chest tightness 

"If you have COPD, you may be short of breath all the time, even sitting down," explained Dr. Edelman. "It more typically occurs every time you exercise." COPD is more common in older individuals and tends to get worse over time.

Smoking is the number one risk factor for COPD, and healthcare providers urge people with the condition who still smoke to quit.

There's no cure for the condition, but treatments vary depending on its severity. These span the spectrum from medications, oxygen therapy, surgery, or, in extreme cases, a lung transplant.

Pulmonary Embolism

pulmonary embolism is a clot that has traveled from another part of your body (usually your legs) to your lungs. It causes sudden and severe shortness of breath, along with other symptoms such as:

  • Sudden and severe shortness of breath
  • Chest pain
  • Coughing with blood

Some people are genetically predisposed to pulmonary embolisms or may be at risk because they smoke, are overweight, have been injured, or have other conditions (such as cancer). 

Also, people who take certain medications, like birth control pills, may have an increased risk of developing a pulmonary embolism. Not moving for long periods also raises your risk, which is why long plane trips can be dangerous for some people.

You can help prevent pulmonary embolisms by regularly moving (especially on long trips), drinking plenty of fluids, and wearing compression socks. 

The condition is potentially fatal and needs to be treated right away. Healthcare providers usually treat pulmonary embolisms with blood thinners or surgery.

Carbon Monoxide Poisoning

Carbon monoxide is a severe hazard that can lurk very close to home. It's an odorless, tasteless, invisible gas produced by burning fuels in cars, trucks, fireplaces, furnaces, and grills. 

If you breathe it in—say, as it builds up in a small space with no ventilation, like a closed garage—it takes the place of oxygen in your red blood cells, which can lead to brain damage or even death.

In addition to shortness of breath, carbon monoxide poisoning symptoms can include the following:

  • Confusion
  • Dizziness
  • Minor headache

"Acute would be a smoke-inhalation-fire scenario," said Sean Drake, MD, a general internist with Henry Ford Health System in Sterling Heights, Mich. "You also see [carbon monoxide building up] in homes. That can be more chronic, insidious."

The best way to prevent carbon monoxide poisoning is to install a carbon monoxide detector in your home. They look and act like the smoke alarms you should also have installed, but they measure the concentration of carbon monoxide in the air. Also, check your heating system yearly, ensure good ventilation for all your appliances, and don't run your vehicle inside a closed garage.

Allergic Reactions

Severe allergic reactions—called anaphylaxis, anaphylactic shock, or allergic shock—sometimes develop in response to specific allergens. Bee stings and peanuts are common examples.

Shortness of breath will quickly escalate if the reaction causes your throat to swell and close off, blocking your air supply. Other symptoms of severe allergic reactions include:

  • Itching
  • Wheezing
  • Vomiting
  • Diarrhea

The remedy is getting a shot of epinephrine (adrenaline) immediately. Usually, people who have severe allergies carry EpiPens (which quickly deliver epinephrine by injection) with them.

If you don't have an EpiPen or don't know whether you have an allergy but suddenly have symptoms of a severe allergic reaction, immediately head to an emergency room or call 911.


Most people choking on a piece of food or anything else lodged in their throat usually know it immediately. It interrupts breathing and can kill you. In addition to shortness of breath, symptoms of choking include:

  • Inability to speak
  • Noisy breathing or high-pitched sounds while inhaling
  • Weak, ineffective coughing
  • Bluish skin color
  • Loss of consciousness (unresponsiveness) if the blockage is not cleared

Coughing is a good thing and should be encouraged. It means your body is trying to expel the object. Talking is also good. 

"That means air is passing across your vocal cords," explained Dr. Drake.

It doesn't mean you're out of the woods, though. You still need to get rid of the problem. 

The Heimlich maneuver is often effective. It involves someone standing behind the choking person and wrapping your arms around their waist. They should forcefully push into the choking person's abdomen, slightly above their belly button, until they spit out the object. You can even do the Heimlich maneuver on yourself by making a fist with one hand and then pushing it into your abdomen with the other hand.


Pneumonia is an infection in your lungs. There are two types: viral and bacterial. According to Dr. Edelman, shortness of breath is common with viral pneumonia (which tends to be less severe than bacterial pneumonia) and walking pneumonia (a mild case of pneumonia).

Pneumonia generally causes your airways to swell and the air sacs in your lungs to fill with mucus, leading to shortness of breath and fatigue. Other symptoms of pneumonia include:

  • Cough, which may produce greenish, yellow, or even bloody mucus
  • Fever, sweating, and shaking chills
  • Rapid, shallow breathing
  • Sharp or stabbing chest pain that gets worse when you breathe deeply or cough
  • Loss of appetite, low energy, and fatigue
  • Nausea and vomiting, especially in small children
  • Confusion, especially in older people

Bacterial pneumonia can come on suddenly or over a few days and may also bring a high fever. Viral pneumonia usually appears over a few days and can feel much like the flu.

You can treat bacterial pneumonia with antibiotics, while antiviral medications may help with viral pneumonia. Vaccines against Streptococcus pneumoniae bacteria, the most common cause of bacterial pneumonia, are recommended for young children, older adults, and people with certain health conditions.

Low Blood Pressure

Less common than high blood pressure, low blood pressure (also called hypotension) can cause various symptoms, including shortness of breath and the following:

  • Confusion
  • Dizziness or lightheadedness
  • Fainting
  • Feeling tired or weak
  • Blurry vision
  • Headache
  • Neck or back pain
  • Nausea
  • Heart palpitations, or feeling that your heart is skipping a beat, fluttering, or beating too hard or too fast

Low blood pressure can be caused by dehydration (even from strenuous exercise), infection, pregnancy, certain medications, and medical conditions.

There are also specific types of low blood pressure. Orthostatic hypotension, for instance, is when your blood pressure suddenly drops when you stand up from sitting or lying down. Postprandial hypotension happens after you eat. Abnormalities in your brain or nervous system can also cause blood pressure to drop.

Prevent low blood pressure episodes by staying hydrated, eating enough salt, avoiding alcohol, wearing compression socks, and ruling out any medical conditions or medications that may be contributing to your symptoms.

Heart Issues

Shortness of breath with or without chest discomfort can signify a heart attack. Other symptoms of a heart attack include:

  • Chest discomfort
  • Pain in other areas of the upper body, such as one or both arms, the back, neck, jaw, or stomach
  • Breaking out in a cold sweat, nausea, or lightheadedness

Heart attacks are medical emergencies. Call 911 if you suddenly experience any of the warning signs.

Shortness of breath can also indicate fluid buildup due to a problem with the heart's valves or its ability to pump blood. 

"Fluid buildup affecting the left side of the heart can produce wheezing that simulates bronchial asthma," said Michael Miller, MD, professor of cardiovascular medicine at the University of Maryland School of Medicine. "Once the valve is fixed, fluid no longer builds up in the lungs, and the patient breathes easier."


Being overweight or obese can aggravate symptoms of asthma

"The heavier you are, the more likely you are to have asthma and more severe," explained Dr. Edelman, adding that being overweight can make breathing hard for anyone, regardless of whether they have asthma. "Some of it is mechanical. Pressure on the chest wall or pressure on the diaphragm from excess fat compresses the lungs." 

According to Dr. Edelman, inflammatory hormones secreted by excess body fat may also constrict the airways.

Shortness of breath is also a symptom of obesity hypoventilation syndrome (OHS). That's when inadequate breathing due to pressure on the chest lowers oxygen levels while raising carbon dioxide levels in the blood. Untreated, OHS can lead to heart problems and even death.


Smokers may not realize that the habit is causing shortness of breath even if they haven't been puffing for all that long.

"People are very, very good at denying symptoms, especially smokers who want to continue smoking and not admit they're having problems," said Dr. Edelman. "People will have some degree of shortness of breath but not recognize it. You learn to live with the symptoms."

Smokers' lungs become inflammed in the small airways and tissues. That can make the chest feel tight or cause wheezing or shortness of breath. After years of lung irritation, smokers may develop a chronic cough with mucus.

The longer you smoke, the worse shortness of breath and other symptoms will become, possibly leading to COPD, lung cancer, and other conditions.

So, if you don't smoke, don't start. And if you do smoke, quit. 

"You do get healthier over time if you quit," noted Dr. Edelman.

Lung Cancer

Not surprisingly, different lung conditions—including lung cancer—can cause shortness of breath at different stages in their development. Other symptoms may include:

  • Coughing that gets worse or doesn’t go away
  • Chest pain
  • Wheezing
  • Coughing up blood
  • Feeling very tired all the time
  • Weight loss with no known cause

"The terrible thing about lung cancer is when it starts and when it's in the stage that it's curable, it [often] doesn't cause symptoms because it's localized," said Dr. Edelman. "If it grows so large, it blocks the airway. Then, you'll get shortness of breath." 

Broken Ribs

Broken ribs can cause shortness of breath and piercing pain, but they can also puncture your lung and lead to a collapsed lung, also called a pneumothorax.

"With a collapsed lung [...], it's both pain and shortness of breath," explained Dr. Edelman. "If you suddenly get shortness of breath and severe pain, head to the emergency room."

There's no specific treatment for fractured ribs—you must let them heal—but healthcare providers can care for a collapsed lung. Observation and oxygen therapy may be all that's needed if only a tiny portion of the lung has collapsed.

And when it's a more significant portion, a healthcare provider inserting a needle or tube into the chest can help. If that doesn't work, surgery may be necessary.

Fractured ribs also raise the risk of pneumonia, especially among older people.


One of the classic symptoms of an anxiety attack is feeling like you can't breathe. Other symptoms of anxiety may include:

  • Anxious thoughts or beliefs: These are hard to control, making you feel restless and tense and interfering with your daily life. They do not go away and can get worse over time.
  • Physical symptoms: This include a pounding or rapid heartbeat, unexplained aches and pains, dizziness, and shortness of breath.
  • Changes in behavior: You may avoid everyday activities that you used to enjoy.

"The feeling of hyperventilating, feeling like you can't catch your breath, is very common [...] in the setting of an acute anxiety attack," said Dr. Drake.

What's more, feeling short of breath can then make you more anxious, creating a vicious cycle, sometimes leading to outright panic.

Learn to manage anxiety with relaxation and deep breathing techniques (it helps expand your lungs, so you breathe in more air) and avoid the things that trigger you. A mental health professional can help you with that technique. Additionally, limit caffeine and alcohol and avoid cigarettes, which can heighten anxiety.


Iron is essential to the body. The mineral helps produce red blood cells—cells that carry oxygen from the lungs throughout the body—and supports physical growth and brain development.

If you have anemia, your blood does not carry enough oxygen to the rest of your body. The most common cause of anemia is not having enough iron. Some evidence suggests that iron deficiency happens in about 4.5% to 18% of people in the United States.

At first, you may feel short of breath more frequently when climbing stairs or completing your usual workout. Eventually, you may start getting breathless when resting. In addition to shortness of breath, anemia may cause symptoms such as:

  • Fatigue
  • Dizziness
  • Irritability

When To Reach Out to a Healthcare Provider

If you're experiencing shortness of breath, your healthcare provider can help identify the cause and treatment. Most shortness of breath is manageable with appropriate medication, breathing techniques, and exercise.

If chest pain or pressure, fainting, or nausea accompanies shortness of breath, you should treat it as a medical emergency.

A Quick Review

Reasons why you may feel shortness of breath can be as harmless as exercise or as severe as lung cancer. Don't ignore any sudden changes in your breathing. 

Let your healthcare provider know if you are experiencing shortness of breath. They can perform diagnostic tests on your body and help you understand and resolve the symptom.

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  2. National Heart, Lung, and Blood Institute. COPD - symptoms.

  3. National Library of Medicine. Pulmonary embolism.

  4. National Library of Medicine. Carbon monoxide poisoning.

  5. National Library of Medicine. Anaphylaxis.

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  7. National Library of Medicine. Choking.

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  11. Centers for Disease Control and Prevention. Pneumococcal caccination.

  12. National Heart, Lung, and Blood Institute. Low blood pressure.

  13. American Heart Association. Warning signs of a heart attack.

  14. National Library of Medicine. Obesity hypoventilation syndrome.

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  16. Centers for Disease Control and Prevention. What are the symptoms of lung cancer?

  17. National Library of Medicine. Rib fracture.

  18. National Library of Medicine. Anxiety.

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