Medically Reviewed by Gabriela Pichardo, MD on November 18, 2022



Your airways suddenly narrow and swell. You may struggle for air, cough up mucus, or hear whistling when you breathe.

It’s not clear why this happens to some people, but lots of things could trigger an attack, including pollen, dust, smoke, exercise, freezing air, a cold, and stress.

Your doctor can help you figure out what causes yours. They might prescribe medication for you to inhale during an attack to help you breathe more easily.




Pollen, dust, pet dander, and other things you breathe in can cause allergies.

Sometimes the allergic reaction causes asthma. But it’s not always something in the air. It could start with something you touch, or some food you eat.

Talk with your doctor about how best to manage your asthma and allergies. Make sure to check in when your symptoms change, too.




You may breathe harder when you’re scared or worried. It’s usually not a big deal, but it can be serious if you already have lung problems like COPD. Sudden stress, like a car accident, could trigger an attack if you have asthma.

Even if you’re otherwise healthy, anxiety might cause you to breathe fast enough to get lightheaded and pass out. 

Carbon Monoxide

Carbon Monoxide


It’s a colorless, odorless gas that can come from furnaces, fireplaces, water heaters, dryers, and car fumes. If it isn’t sent out the right way, it can build up in the air, and you could breathe too much of it. That makes it hard for your red blood cells to send oxygen through your body.

You may be short of breath, dizzy, confused, weak, and nauseated. Your vision could blur, and you could pass out. It could be life-threatening. 

A Cold

A Cold


It happens thanks to a virus that causes a runny nose, sneezing, and sometimes fever. It may irritate your lungs and airway, and bring a cough that can make it hard to breathe.

There’s no cure, but it usually gets better on its own in a week or so. See your doctor if you have a fever higher than 102 F, if you’re wheezing, or if it’s hard to catch your breath. 




This serious respiratory disease is caused by a type of virus called a coronavirus. Infected people spread it through tiny drops left behind when they cough, sneeze, or talk. The virus first attacks cells in your airways, but it can spread quickly to your lungs.

Along with shortness of breath, the most common warning signs are fever and a dry cough.

So far, there's no cure for COVID-19. Most people have mild symptoms and can get better at home. But call your doctor's office or 911 right away if you have real trouble breathing.

Pulmonary Embolism

Pulmonary Embolism


A blockage, or clot, often in your leg, breaks loose, and a piece goes to your lung and blocks blood flow. That can make it hard or painful to breathe. You could feel faint, and your heart might race. Some people cough up blood. You may have swelling, warmth, and soreness where the clot started.

If any of this happens to you, get to the hospital, as it can be life-threatening. Your doctor may use blood thinners, other drugs, or surgery.

Sleep Apnea

Sleep Apnea


It’s a condition when breathing stops repeatedly during sleep, so a person may not realize anything is happening. But you might be tired, groggy, and moody the next day. It could lead to high blood pressure and make you more likely to have heart disease and a stroke.

Extra weight is a risk. It may help to lose weight, but not all people with sleep apnea are overweight. 




A virus, bacteria, or fungus infects the air sacs inside your lungs. Then those sacs fill with fluid. This makes it harder to breathe. You also could have chills and fever, and you might cough up a thick, colored mucus. 

Check in regularly with your doctor. They might prescribe antibiotics if your pneumonia is caused by bacteria. Other types are harder to treat, but rest, fluids, and over-the-counter meds can make you feel better.




Some people call it “chronic bronchitis” or emphysema. Smoking causes it most often. It stretches out the air sacs in your lungs, making it hard for the lungs to move air. This makes it tougher to breathe. You might feel tightness in your chest and have a cough, sometimes with wheezing, that doesn’t go away.

Your doctor can help you manage this serious condition. If you smoke, the most important step you can take is to quit smoking.  

Heart Failure

Heart Failure


It doesn’t mean your heart has “failed,” just that it’s not as strong at pumping blood as it should be. That makes it harder to get oxygen where it needs to go. Blood backs up in your lungs. That can make you short of breath.

Simple things -- when you climb stairs, walk a long way, or carry groceries -- might tire you out.

Your doctor can help you manage your symptoms.




When your body doesn’t have enough healthy red blood cells, you can’t get enough oxygen to your tissues. That can make you weak and tired, and sometimes short of breath. It can also make you dizzy and pale, with cold hands and feet, and a fast heartbeat.

Lots of things cause it, so treatment depends on what’s causing yours. Talk to your doctor if you’re tired and can’t figure out why.

A Collapsed Lung

A Collapsed Lung


Doctors sometimes call it pneumothorax. It happens when an injury or disease causes air to leak from your lungs to the space between your lungs and the wall of your chest. The air pushes on the lung, making it fold in on itself.

You could have chest pain and be short of breath. Your doctor may put a needle or small tube into the area to remove the air, or you may need surgery. But if it’s minor, it might get better on its own.

Crying or Being Scared

Crying or Being Scared


Kids between 6 months and 6 years of age can sometimes have moments when they stop breathing while crying or when they become startled.  This sometimes triggers a “cyanotic spell,” an uncontrolled response that makes them faint.

The child may turn blue and pass out for about a minute. They could seem groggy afterward. Though it can be scary at first, it’s nothing to worry about, and it might happen again and again.

Myasthenia Gravis

Myasthenia Gravis


It’s a “neuromuscular” disease that makes it harder for muscles and nerves to talk to each other. You might notice weakness when you move your arms and legs. It can also affect automatic movements like breathing. The disease could change the way you chew, swallow, blink, and smile. It’s usually worse if you exert yourself and better after you rest.

Your doctor can help you manage your symptoms. In some cases, people go into remission.

A Broken Heart

A Broken Heart


It’s a real thing. There’s even a name for it: broken heart syndrome. Sudden, intense emotion -- a lost loved one or ended romance, for example -- affects the heart, causing sharp chest pain and making it hard to breathe. The heart doesn’t pump as well for a while. Tests show changes in heartbeat rhythm and substances in the blood that mimic a heart attack.

Unlike a heart attack, however, broken heart syndrome doesn’t happen because your arteries are blocked. While it can lead to short-term heart muscle failure, most people get better within a few days or weeks.

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American Heart Association: “Treatment Options for Heart Failure,” “Causes and Risks for Heart Failure,” “Warning Signs of Heart Failure,” “Is Broken Heart Syndrome Real?”

American Lung Association: “Pneumonia,” “Carbon Monoxide.”

American Psychological Association: “Stress effects on the body.”

CDC: “Smoking and COPD,” "How Coronavirus Spreads," "Symptoms of Coronavirus," "What to Do if You Are Sick."

Cleveland Clinic: “Pulmonary Embolism.”

Mayo Clinic: “Common cold,” “Pneumothorax,” “Anemia,” “Carbon monoxide poisoning,” “Allergies and asthma: They often occur together,” “Asthma.”

NIH National Heart, Lung, and Blood Institute: “What is COPD?” “Venous Thromboembolism.”

NIH National Institute of Neurological Disorders and Stroke: “Myasthenia Gravis Fact Sheet.”

NIH National Institute of Diabetes and Digestive and Kidney Disorders: “Health Risks of Being Overweight.”

Nemours Foundation: “About Breath-Holding Spells.”

National Health Service: “Breath-holding spells in children.”

PubMed Health: “Pulmonary Embolism.”