Most coughs can wait a few days, but these breathing symptoms can’t

Key takeaways

• In July 2024, a bacterium called Mycoplasma pneumoniae caused 53.8% of pneumonia hospital stays at 42 U.S. children’s hospitals, up from under 5% a year in 2021 to 2023¹.
• CDC’s provisional counts show 35,435 whooping cough cases in 2024 and 28,783 in 2025, and 10 of the 16 deaths reported in 2025 were babies under 1³.
• Sudden shortness of breath with pain on a deep breath can signal a blood clot in the lung, and pregnancy or a recent birth makes a clot more than five times as likely⁴⁶.
• In women, a heart attack can show up as shortness of breath, nausea, back or jaw pain or unusual tiredness, and the American Heart Association says to call 911⁷.
• A cough that lasts more than 8 weeks is chronic, and coughing up blood, night sweats or weight loss you can’t explain call for a prompt check¹⁰.

In July 2024, more than half the children admitted with pneumonia at 42 U.S. children’s hospitals, 53.8%, had an infection with Mycoplasma pneumoniae¹.

From 2021 through 2023, that germ had caused fewer than 5% of those hospital stays each year¹. In 2024 alone, the hospitals recorded 10,298 stays for it, compared with 6,055 over the six years before, a CDC report found¹.

CDC calls Mycoplasma infections generally mild and a common cause of “walking pneumonia”². The 2024 cases weren’t more severe than earlier ones¹. But mild on average didn’t mean every child could stay home.

Most coughs and stuffy chests are ordinary. A few breathing patterns can turn deadly within hours, and some of the most dangerous don’t feel like lung problems at all.

This guide sorts them by urgency: call 911, get care the same day, call this week or watch at home. CDC’s emergency signs for flu and sepsis are in our articles on respiratory infection prevention and on sepsis.

Three emergencies that can feel like “just” being out of breath

A blood clot in the lung

A pulmonary embolism, or PE, happens when a blood clot travels to the lungs and blocks blood flow. Its common symptoms are shortness of breath, pain with a deep breath, fast breathing and a racing heart, the National Heart, Lung, and Blood Institute (NHLBI) says⁴. Less common ones include a cough, sometimes with blood, lightheadedness or fainting, sweating, and anxiety or a sense of dread⁴.

Symptoms can hit within seconds or build over days to weeks, and some people have none⁴. Untreated, a PE can lead to a heart attack, shock, stroke or death⁴.

Context helps. NHLBI lists these risk factors for clots⁵⁶:

• a flight longer than 4 hours, or bed rest in a hospital or nursing home;
• major surgery, with risk highest in the first 3 months afterward;
• cancer, a past clot, or infections such as COVID-19;
• pregnancy and the first 6 weeks after birth, when clots are more than 5 times as likely;
• some types of birth control pills, especially in the first few months of use, and hormone therapy;
• age, with risk nearly doubling every 10 years after 40.

NHLBI says to call your health care provider right away if you think you have clot symptoms⁴. If breathing is hard or you feel lightheaded, call 911, as the National Library of Medicine’s MedlinePlus advises for serious breathing trouble⁸.

A heart attack that looks like breathlessness

Chest pain is the most common heart attack symptom in women and men alike, the American Heart Association (AHA) says⁷. But shortness of breath can come with chest discomfort or without it⁷.

Women may also notice anxiety, an upset stomach, pain in the shoulder, back or arm, or unusual tiredness or weakness⁷. The AHA’s advice for heart attack signs is to call 911 and get to a hospital right away⁷.

Heart failure, where the heart can’t pump well enough, can also announce itself through breathing. MedlinePlus flags a cough that worsens when you lie down, leg swelling or known heart disease as possible heart failure signs, and advises calling your provider right away¹⁰. MedlinePlus lists being unable to breathe lying down, so you have to sit up, among the breathing-trouble signs that call for 911⁸.

A collapsed lung

A pneumothorax, or collapsed lung, happens when air leaks into the space between the lung and the chest wall⁹. It often brings sharp chest or shoulder pain that worsens with a deep breath or a cough, plus shortness of breath⁹.

It can follow an injury, a lung disease such as asthma or COPD, or the bursting of small air blisters on the lung, sometimes with pressure changes from scuba diving or high altitude⁹. Tall, thin people and smokers face higher risk, and it can happen again⁹. MedlinePlus says to contact your provider if you have symptoms, especially if you’ve had one before⁹.

A fourth emergency, anaphylaxis, is a severe allergic reaction: call 911 for trouble breathing with hives or a swollen face or throat¹⁰. Our upcoming allergy-care article covers epinephrine.

When anxiety and an emergency feel the same

Many people who feel short of breath wonder whether it’s “just anxiety.” The official symptom lists show why that’s hard to judge alone.

Anxiety or a sense of dread appears on NHLBI’s list of clot symptoms⁴. Anxiety appears on the AHA’s list of heart attack symptoms in women⁷. And MedlinePlus counts being very anxious and agitated among the signs of serious breathing trouble⁸.

So anxiety can be part of an emergency, not proof that nothing is wrong. Treat “it’s only panic” as a conclusion a clinician reaches after checking, especially the first time, or when an episode feels different from your usual ones. MedlinePlus is plain about the risk of waiting: don’t hold off to see whether serious breathing trouble improves on its own⁸.

If you live with panic attacks, our articles on anxiety treatment and on breath awareness cover therapies that have been tested.

Cough red flags: blood, weeks and night sweats

MedlinePlus sorts coughs by how long they last¹⁰. An acute cough, often from a cold, flu or sinus infection, usually fades within 3 weeks. A subacute cough lasts 3 to 8 weeks, and a chronic cough lasts longer than 8 weeks¹⁰.

Common causes of a lingering cough include postnasal drip, asthma, acid reflux, smoking and a class of blood pressure and heart medicines called ACE inhibitors¹⁰. If you take one and develop a cough that won’t quit, mention it to your prescriber rather than stopping the medicine yourself.

MedlinePlus advises contacting your provider right away for¹⁰:

• a cough that lasts longer than 10 to 14 days;
• a cough that brings up blood;
• a fever, or thick, foul-smelling yellow-green phlegm;
• weight loss you can’t explain, or night sweats;
• contact with someone who has tuberculosis;
• a harsh, high-pitched noise on each breath in, called stridor;
• any cough in a baby younger than 3 months.

Tuberculosis, or TB, is still around. CDC counted 9,633 cases of TB disease in the U.S. in 2023, and 565 people died of TB-related causes in 2022¹¹. Its lung form typically brings a bad cough lasting 3 weeks or longer, chest pain, coughing up blood or phlegm, weight loss, night sweats, fever and chills¹¹.

TB spreads through the air, and it can almost always be cured with several medicines taken for 4 to 6 months or longer¹¹. If you’ve smoked, ask too whether you’re due for lung cancer screening. Our article “Why some screenings have stop ages, since they take a decade to pay off” covers who qualifies.

Whooping cough and walking pneumonia came back hard

Reported cases of whooping cough, or pertussis, dropped during the COVID-19 pandemic, likely because masking and distancing slowed its spread, CDC says³. Then they rebounded.

CDC’s provisional reports counted 35,435 cases in 2024, more than in 2019, with a peak in November 2024³. The 2025 count, 28,783, was lower but still above pre-pandemic levels³. For scale, the country typically logged more than 10,000 cases a year before the pandemic, with a high of 48,277 in 2012³. So far, 2026 is running below 2025 at the same point³.

Babies under 1 face the greatest risk of serious illness and death³. Of the 16 pertussis deaths reported for 2025, 10 were infants³. Babies younger than 6 months were reported at about 120 cases per 100,000, or roughly 1 in 830 by our math³.

MedlinePlus advises calling the doctor right away about any cough in a baby under 3 months¹⁰. Lips or a face that turn bluish during coughing need care right away, and a baby who stops breathing needs 911¹².

CDC also notes that protection from today’s whooping cough vaccines fades over time, one reason cases climbed in the decades before the pandemic³. Our vaccine schedules article covers who recommends which shots.

Mycoplasma surged in 2024 as well. Its biggest jump came in the youngest children: the share of pneumonia stays it caused rose about eightfold in babies and toddlers¹. About 1 in 5 children hospitalized with it in 2024 needed intensive care, a lower share than in earlier years¹. CDC says infections have been falling since early 2025 but stayed elevated in some regions into 2026².

Children: the signs that mean go now

The American Academy of Pediatrics’ HealthyChildren.org symptom checker, written by pediatrician Barton Schmitt, flags these signs¹²:

• fighting for every breath, or breathing so labored the child can hardly talk or cry;
• ribs pulling in with each breath, called retractions;
• breathing far faster than usual;
• lips or face turning blue.

It says to call 911 for severe trouble breathing, a child who passes out or stops breathing, or lips that stay bluish when the child isn’t coughing¹². Go to the ER now for any baby under 1 with trouble breathing, for retractions, or for stridor or loud wheezing¹².

Bronchiolitis is swelling of the smallest airways, mostly in babies, often from RSV¹⁴. Cold symptoms come first. A day or two later, the cough often deepens and the baby’s breathing quickens¹⁴. Call the pediatrician for flaring nostrils, grunting, pulling in under the ribs, a tightening belly with each breath, trouble sucking or swallowing, or bluish lips¹⁴. Antibiotics don’t help, but saline drops, gentle suction and fluids can¹⁴.

Croup is a viral infection of the voice box that causes a barking, seal-like cough and a hoarse voice¹³. It usually lasts 5 to 6 days and is worse at night¹³. Severe croup brings stridor, a harsh sound on each breath in¹³.

Call 911 if a child with croup struggles for each breath, has constant severe stridor, or drools and has great trouble swallowing¹³. For milder croup, the same guide suggests 20 minutes of warm mist in a closed, steamy bathroom, or a few minutes of cool outdoor air¹³. Skip very hot steam, which can burn¹³.

What a pulse oximeter can and can’t tell you

A fingertip pulse oximeter uses light to estimate how much oxygen your blood carries¹⁵. Most healthy people read 95% to 100%, the FDA says, though readings can run lower with lung or heart disease and at high altitude¹⁵.

The number is an estimate. Poor circulation, skin pigmentation, skin thickness, skin temperature, tobacco use and nail polish can all throw it off¹⁵. Oximeters sold for wellness, sports or aviation aren’t reviewed by the FDA before sale¹⁵.

Most important, the FDA warns that some people with low oxygen have few or no symptoms, and that readings should be weighed alongside how you feel¹⁵. Use an oximeter to track a trend, writing down the date and time of each reading¹⁵. Don’t let a reassuring number talk you out of help when warning signs are present.

For how skin tone affects readings, see our article on wearable accuracy.

The breathing-symptom urgency guide

This guide is ours: the urgency levels are our cautious reading of the official warning signs above. It isn’t a complete list. When you’re unsure, call.

Symptom pattern	Possible causes	What to do now
Struggling to breathe, can’t speak normally, very fast breathing, bluish lips or nails, can’t breathe lying down, or confused or very sleepy	Asthma attack, pneumonia, heart failure, clot, others	Call 9118
Chest pressure or pain, or breathlessness with cold sweat, nausea, lightheadedness, or arm, back, neck or jaw pain	Heart attack	Call 9117
Sudden breathlessness, pain on a deep breath, racing heart or lightheadedness, especially after surgery, a long trip, pregnancy or starting birth control pills	Blood clot in the lung	Call 911 if breathing is hard or you feel faint8; otherwise call your provider right away4
Trouble breathing with hives or a swollen face or throat, or after a sting, food or new medicine	Anaphylaxis	Call 9111012
Child struggling for each breath, passing out, bluish lips when not coughing, or drooling with stridor	Severe croup, blocked airway	Call 9111213
Baby under 1 with any trouble breathing; ribs pulling in; stridor; loud wheezing	Bronchiolitis, croup, asthma	Go to the ER now12
Sharp chest or shoulder pain with breathlessness, especially if tall and thin, a smoker or living with lung disease	Collapsed lung	Same day: call your provider; 911 if breathing is hard89
Cough worse lying down, with leg swelling or known heart disease	Heart failure	Same day: call your provider right away10
Coughing up blood; night sweats or weight loss you can’t explain; TB contact; any cough in a baby under 3 months	Infection, TB, clot, cancer, whooping cough	Same day: call your provider right away1011
Fever with a cough and some breathlessness	Pneumonia, other infections	Same day: call your provider right away810; 911 if breathing is hard or the person seems confused810
A cough lasting more than 10 to 14 days, with no red flags above	Postnasal drip, asthma, reflux, medicines, others	Same day: call your provider10
A croup cough lasting more than 14 days	Lingering croup, other causes	This week: call the doctor13
An oximeter reading that worries you, with no warning signs	Device error or a real drop	This week: call your provider and share your logged readings15
A cold-like cough that’s getting better and hasn’t passed 10 to 14 days, with no red flags above	Viral cold	Watch at home10
Mild croup without stridor at rest	Viral croup	Watch at home: warm mist or cool air, keep the child calm13

Listening to your body is the first step, not the last

Natural health starts with paying attention to your own body, and this guide depends on that skill. Noticing that a cough has lingered, that you can’t lie flat or that your child’s ribs pull in with each breath is the self-awareness that catches problems early¹⁰¹².

Comfort care has its place for ordinary colds, as our article on sick days explains. The skill is knowing when a symptom has moved from the comfort column to the call column. Getting checked quickly isn’t giving up on natural care. It’s what keeps natural care safe for everything else.

Questions readers ask

The bottom line

Most coughs and stuffy chests are ordinary and fade with time and comfort care. A few patterns can’t wait: sudden breathlessness with chest pain, breathlessness after surgery, travel or a new birth, trouble breathing lying flat, blue lips, a child whose ribs pull in, and any breathing trouble in a young baby.

Anxiety can be part of an emergency rather than its explanation, and a good oximeter number can’t overrule a warning sign. When a symptom fits the 911 or same-day rows, act first and sort out the cause later.

Related reading

• One CDC plan now covers colds, flu and COVID-19, with prevention in layers
• Inflammation isn’t always infection, and sepsis is the infection that can’t wait
• Chicken soup won’t cure a cold, and comfort still counts until it delays care
• Your wearable gets resting pulse right, while calories and sleep are another story
• Lung rehab is the best-tested breathing help for COPD, yet few patients ever start it

Sources

1. Diaz MH, Hersh AL, Olson J, Shah SS, Hall M, Edens C. “Mycoplasma pneumoniae Infections in Hospitalized Children — United States, 2018–2024.” Morbidity and Mortality Weekly Report, 2025;74(23):394-400, June 26, 2025. cdc.gov
2. Centers for Disease Control and Prevention. “Mycoplasma pneumoniae Infection Surveillance and Trends.” CDC, last updated May 18, 2026. cdc.gov
3. Centers for Disease Control and Prevention. “Pertussis Surveillance and Trends” (last updated July 10, 2026) and the “2025 Provisional Pertussis Surveillance Report” linked from it (data as of January 26, 2026). CDC. cdc.gov and cdc.gov
4. National Heart, Lung, and Blood Institute. “Venous Thromboembolism: Pulmonary Embolism (PE).” NIH, last updated September 19, 2022. nhlbi.nih.gov
5. National Heart, Lung, and Blood Institute. “Venous Thromboembolism: Causes and Risk Factors.” NIH, last updated September 19, 2022. nhlbi.nih.gov
6. National Heart, Lung, and Blood Institute. “Women and Venous Thromboembolism (VTE).” NIH, last updated September 20, 2022. nhlbi.nih.gov
7. American Heart Association. “Heart Attack Symptoms in Women.” AHA, last reviewed December 13, 2024. heart.org
8. MedlinePlus, National Library of Medicine. “Breathing difficulties – first aid.” Review date January 8, 2025. medlineplus.gov
9. MedlinePlus, National Library of Medicine. “Collapsed lung (pneumothorax).” Review date January 8, 2025. medlineplus.gov
10. MedlinePlus, National Library of Medicine. “Cough.” Review date April 1, 2025. medlineplus.gov
11. Centers for Disease Control and Prevention. “About Active Tuberculosis Disease.” CDC, October 30, 2024. cdc.gov
12. Schmitt BD. “Breathing Trouble” (symptom checker). HealthyChildren.org, American Academy of Pediatrics. healthychildren.org
13. Schmitt BD. “Croup” (symptom checker). HealthyChildren.org, American Academy of Pediatrics. healthychildren.org
14. American Academy of Pediatrics. “Bronchiolitis in Babies.” HealthyChildren.org, last updated December 17, 2025. healthychildren.org
15. U.S. Food and Drug Administration. “Pulse Oximeter Basics.” FDA Consumer Update, March 26, 2025. fda.gov