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- Shortness of breath can be caused by non-emergency reasons like anxiety or pregnancy.
- It can also be caused by life-threatening conditions like a blood clot, heart attack, or allergy.
- If you aren't sure what is causing your shortness of breath, you should see a doctor immediately.
- Visit Insider's Health Reference library for more advice.
Feeling short of breath can be scary – you try to breathe in but struggle to get enough air, causing you to breathe faster and feel even more scared, stressed, and anxious about the situation.
In some cases, shortness of breath isn't an emergency and may be caused by something like anxiety or pregnancy. But it can also be a sign of a life-threatening condition like an allergic reaction or heart attack.
Here are five reasons you may be feeling out of breath and when you should get immediate medical attention.
1. Allergic reaction
Allergic reactions happen when your immune system overreacts to a trigger. . Some common allergens include: dust mites, pollen, and pet dander.
"Allergic reactions can cause the throat to tighten which creates difficulty breathing and shortness of breath," Troy Madsen, MD, a professor of emergency medicine at the University of Utah.
This type of reaction, called anaphylaxis, is relatively common - up to one in 20 Americans experience anaphylaxis at some point.
Some other common symptoms of a serious allergic reaction are:
- Swollen tongue
- Nausea and vomiting
- Itching or hives on skin
- Dizziness or fainting
Luckily, there's an easy way to immediately treat shortness of breath due to allergic reactions: an EpiPen (epinephrine injector). However, it's important to note that an EpiPen is a temporary fix and you should still call 911 for additional help, says Madsen.
Allergic reactions can be extremely dangerous - if your throat closes fully, you can die from suffocation. However, these deaths are rare - only about 0.3% of people who have anaphylaxis die from it.
2. Blood clot in your lung
Pulmonary embolism is a serious, life-threatening condition that happens when a blood clot travels into your pulmonary artery and blocks blood flow to your lungs.
A p pulmonary embolism decreases blood flow to the lungs, therefore decreasing the amount of blood that can be oxygenated to provide oxygen for the rest of the body - causing shortness of breath.
Along with shortness of breath, symptoms of pulmonary embolism include chest pain that gets worse with a deep breath and coughing up bloody mucus. People over 40 are more likely to experience pulmonary embolism, along with people who have recently had surgery or given birth and people with auto-immune conditions.
"If you experience these symptoms, go to the ER for further testing," Madsen says.
3. Anxiety attack
"Anxiety often leads to a rapid heart rate which, in turn, can cause a sensation of shortness of breath," Madsen says.
Anxiety is a common problem in the US - nearly one in five adults have an anxiety disorder and more than one in ten have an anxiety attack each year.
Some other symptoms of an anxiety attack are:
- Trembling or shaking
- Feeling nauseous
- Sweating
- Intense fear
- Feeling lightheaded or faint
A quick and easy way to calm your breathing from an anxiety attack is to breathe into a paper bag.
Or if you take prescription, fast-acting anxiety medication like Xanax, this can also help calm your system and let you catch your breath.
"In the case of a severe panic attack a person may need to go to the emergency department to receive treatment for this," Madsen says. An ER doctor can give you anti-anxiety medication or help you practice relaxing breathing techniques.
4. Heart attack
The warning signs of a heart attack include:
- Chest pain or pressure that radiates to your back, neck, or jaw.
- Nausea, heartburn, or stomach pain
- Shortness of breath
- Suddenly feeling dizzy or lightheaded
- Fatigue
- Cold sweats
"Heart attacks can cause shortness of breath because the heart muscle is affected and may not be able to adequately deliver blood to the body," Madsen says. When your lungs aren't getting enough blood, you may not get enough oxygen and your lungs won't function properly.
According to the Centers for Disease Control and Prevention, around 800,000 Americans have a heart attack each year. Men over 45 and women over 55 are at greatest risk, along with people who smoke or have high blood pressure.
If you think you may be having a heart attack, call 911 or go to the hospital immediately. You may need an emergency procedure like a stent or coronary bypass surgery to clear a blockage in your coronary artery, Madsen says.
5. Early pregnancy
During the first few weeks after you get pregnant, your body starts to produce more of the sex hormone progesterone. As your progesterone levels rise, you naturally start to breathe faster, which can make you feel short of breath.
Later on in your pregnancy, your uterus grows larger and can put pressure on the diaphragm, which can lead to a gradual increase in shortness of breath, Madsen says.
In most cases, shortness of breath isn't dangerous and should resolve after the pregnancy. However, "severe, sudden shortness of breath in pregnancy is always a concern," Madsen says, because pregnancy can increase the risk of blood clots in your lungs.
Other causes of shortness of breath
Shortness of breath may also be caused by:
- Anemia
- Carbon monoxide poisoning
- Excess fluid around the heart (pericardial effusion/cardiac tamponade)
- Chronic obstructive pulmonary disease (COPD)
- Heart rhythm issues (arrhythmia)
- Collapsed lung
- Pneumonia
- Coronavirus disease 2019 (COVID-19)
Insider's takeaway
Shortness of breath can be caused by several different conditions, some of which, like heart attack or blood clots, can be very serious or even life threatening. If you aren't sure why you're having shortness of breath, or if it comes on suddenly and severely, it's best to get medical attention as soon as possible.