Last updated: September 2026
Walking pneumonia in kids is usually more than a cold when the cough keeps getting worse instead of better after a week, when a low fever, headache, and sore throat come along with it, and when your child stays tired and hacking for two, three, or four weeks. It is caused by a bacterium called Mycoplasma pneumoniae, it comes on slowly, and it does not respond to amoxicillin. A pediatrician can usually sort it out with an exam and, when needed, a quick swab or chest X-ray.
Key takeaways
- Walking pneumonia starts slowly, 1 to 4 weeks after exposure, and the dry cough can linger for weeks even when your child seems mostly fine.
- In 2024 the CDC reported a large rise in Mycoplasma infections in young children, including ages 2 to 4, an age group where it used to be uncommon.
- Many mild cases clear on their own. When antibiotics are needed, azithromycin is the first choice. Amoxicillin does not work against Mycoplasma.
- Fast breathing, pulling in at the ribs, blue or gray lips, or dehydration means the ER.
What is walking pneumonia and why is it called that?
Walking pneumonia is a mild lung infection most often caused by Mycoplasma pneumoniae, a small bacterium spread by coughing and sneezing. It most commonly affects children, and kids with asthma are at higher risk of a more serious infection. [Source: CDC, Causes and How It Spreads: Mycoplasma pneumoniae]
It earned the name because children with it often seem better than you would expect for someone with a lung infection. They are up, playing, and going to school with a nagging cough. [Source: CDC, About Mycoplasma pneumoniae Infection]
That is what makes it easy to miss. A child who is still active but has coughed for two weeks deserves a closer look, even if it seemed like just a cold, not the flu.
Why are more kids getting walking pneumonia right now?
Mycoplasma infections rise in waves every few years, and the most recent wave was unusually large. Between March 31 and October 5, 2024, the share of pneumonia diagnoses in US emergency departments linked to Mycoplasma climbed from 1.0 percent to 7.2 percent in children ages 2 to 4, and from 3.6 percent to 7.4 percent in children ages 5 to 17. [Source: CDC, Mycoplasma pneumoniae Infections Have Been Increasing]
The jump in 2 to 4 year olds got the most attention because Mycoplasma was not historically a leading cause of pneumonia at that age, and children can get it more than once.
What are the symptoms of walking pneumonia in kids?
The hallmark is a slow build. Unlike the flu, which knocks a child flat within a day, Mycoplasma symptoms appear gradually, usually 1 to 4 weeks after exposure. The CDC describes an onset that is “gradual and subacute, slowly progressing to a higher fever and persistent cough,” and notes the illness can drag on for weeks or months. [Source: CDC, Clinical Features of Mycoplasma pneumoniae Infection]
In school-age children and teens, expect some mix of:
- A dry, hacking cough that worsens over the first week, then hangs on for 2 to 4 weeks or longer
- Low-grade fever, often 102°F or lower
- Headache, sore throat, fatigue, and poor appetite
- Wheezing in some kids, especially those with asthma
The picture is different in kids under 5. Mycoplasma often looks like an ordinary cold with a runny nose and sneezing, sometimes with no fever, and it can bring diarrhea, vomiting, and wheezing rather than a classic pneumonia cough. If your toddler has vomiting or loose stools on top of a cough, watch fluids and know the signs of dehydration in toddlers.
How is walking pneumonia different from a cold, RSV, or regular pneumonia?
| Feature | Common cold | Walking pneumonia | Typical bacterial pneumonia | RSV |
|---|---|---|---|---|
| How it starts | Over 1 to 2 days | Slowly, over a week | Often suddenly, sometimes after a cold | In stages over several days |
| Fever | None or low | Low, often 102°F or less | Often high, with chills | Common, varies |
| Cough | Improves in 7 to 10 days | Dry, hacking, lingers 2 to 4 weeks | Wet, child looks sick | Wet, with wheezing |
| Energy and breathing | Normal | Tired but up and around, may wheeze | Very low, fast labored breathing | Fast, wheezy, worst in babies |
RSV shows up within 4 to 6 days of exposure, and in young infants the only signs may be irritability and trouble breathing. [Source: CDC, Symptoms and Care of RSV] Our offices run rapid in-office tests for RSV, flu, strep, and COVID to rule those in or out at the same visit.
How do pediatricians diagnose walking pneumonia?
The diagnosis starts with the story and the exam: how long the cough has lasted, whether classmates or siblings are sick, and whether your child has asthma. Listening to the lungs, checking oxygen, and counting breaths tell us a lot.
When the picture is unclear or the child seems sicker than expected, a chest X-ray can show the patchy pattern typical of Mycoplasma, and a nose or throat swab sent for a PCR test can confirm it. The CDC describes these molecular tests as highly accurate and fast enough to guide treatment. [Source: CDC, Laboratory Testing for Mycoplasma pneumoniae] We test when the answer will change the plan.
How is walking pneumonia in kids treated?
Many mild Mycoplasma infections get better on their own. When a child has true pneumonia, is wheezing, is not improving, or has asthma, antibiotics are usually recommended. Macrolides such as azithromycin are the first-line treatment. Amoxicillin and other penicillin-type antibiotics do not work, because Mycoplasma lacks the cell wall those drugs attack. [Source: CDC, Mycoplasma pneumoniae Infections Have Been Increasing]
So a child put on amoxicillin for a “chest infection” who is not better after 2 to 3 days should be seen again. If azithromycin is prescribed, give every dose even after your child feels better. Expect the cough to outlast the antibiotic by a few weeks. Mycoplasma is a known trigger for asthma flares, and it sometimes reveals asthma in a child with no diagnosis, so kids who wheeze may need inhalers adjusted or nebulizer treatments.
How long is it contagious and when can my child go back to school?
Because the incubation period is so long, Mycoplasma moves through a household or classroom over weeks rather than days. Your child can pass it on while coughing; the risk drops once antibiotics have started and the fever is gone. There is no vaccine, so handwashing and covering coughs are the main ways to slow spread. [Source: CDC, About Mycoplasma pneumoniae Infection]
For school, most Georgia districts use the same rule as for other illnesses: fever-free for 24 hours without fever medicine, 24 hours on any antibiotic, and well enough to take part. A lingering dry cough alone is not a reason to stay home for weeks, but check your school or daycare’s own policy.
How can I care for my child at home?
- Push fluids. Coughing kids lose more fluid than you would think, and good hydration keeps mucus thin.
- Use acetaminophen or ibuprofen (ibuprofen only over 6 months) for fever or discomfort. Review when a child’s fever is worth worrying about.
- Skip over-the-counter cough medicine under age 6. Honey (over age 1) and a cool-mist humidifier are safer.
- Keep asthma medicines on schedule and watch breathing effort at night.
When should I call the pediatrician or go to the ER?
Call for a same-day visit for a cough lasting more than 2 to 3 weeks or worsening after improving, chest pain when breathing, new wheezing, an asthma flare needing the rescue inhaler more often than every 4 hours, or vomiting or diarrhea with fewer wet diapers. Call for any fever of 100.4°F or higher in a baby under 3 months, a fever above 104°F that keeps returning at any age, a fever lasting more than 24 hours in a child under 2, or more than 3 days (72 hours) in a child 2 or older. [Source: AAP HealthyChildren.org, When to Call the Pediatrician: Fever]
Go to the emergency room, or call 911, for:
- Fast, labored breathing, or skin pulling in between and around the ribs with each breath (retractions)
- Flaring nostrils or grunting with breathing
- Pale, gray, or blue lips or nail beds
- Signs of dehydration such as no urine in 8 hours, dry mouth, no tears, or extreme sleepiness
- Confusion or a child who cannot be woken easily
The AAP lists those breathing signs, along with fever that lasts more than a few days despite antibiotics or returns after improving, as pneumonia warning signs. [Source: AAP HealthyChildren.org, Pneumonia] For a cough that is not an emergency, your child’s own doctor is a better first stop than urgent care, because we know their history.
Can walking pneumonia be prevented?
Handwashing, covering coughs, not sharing cups, and keeping a feverish child home are the basics. Staying current on the flu shot and pneumococcal series lowers the odds of a second infection landing on top of a Mycoplasma cough. Georgia’s school vaccination requirements cover most of these, and we can catch your child up at any visit.
How Sun Pediatrics can help
A cough that has gone on for weeks is one of the most common reasons families come to us each fall, and it is worth a visit rather than waiting it out. Every physician is board certified, and our team cares for children from birth through 18 at four North Georgia offices: Marietta, East Cobb, Alpharetta, and Cumming.
We offer same-day sick visits every day, in-office rapid tests for strep, flu, RSV, and COVID, nebulizer treatments for kids who are wheezing, and secure video visits for follow-up once a plan is in place. Hours are Monday to Thursday 8:00 to 4:45 and Friday 8:00 to 4:15, with a Saturday clinic from 9:00 to 12:00 on the 1st and 3rd Saturday.
Request an appointment online or call 678-501-5601. Same-day sick visits are held every day at all four offices.
Frequently asked questions
How long does walking pneumonia last in a child?
Most children feel better within a few days of starting an antibiotic, or within 1 to 2 weeks without one. The cough commonly lingers 3 to 4 weeks.
Is walking pneumonia contagious to the family?
Yes. Because symptoms take 1 to 4 weeks to appear, a sibling may get sick long after the first child is better. Handwashing and separate cups help.
Why did amoxicillin not help my child’s cough?
Amoxicillin attacks the bacterial cell wall, and Mycoplasma does not have one. If your child is not improving after 2 to 3 days on it, see your pediatrician about a switch to azithromycin or a test to confirm the cause.
Does my toddler need a chest X-ray?
Usually not. Many toddlers are diagnosed by exam alone. An X-ray is reserved for children who are working hard to breathe, have low oxygen, or are not improving on treatment.
This article is for general information and is not medical advice. Contact your pediatrician for care specific to your child.
