Key points
- Bacteria called Mycoplasma pneumoniae can cause respiratory tract infections.
- These infections are generally mild but sometimes can be severe.
- Most people will recover without medicine, but some need antibiotics to get better.
- Call a healthcare provider about difficulty breathing or symptoms that concern you.
What it is
M. pneumoniae bacteria cause respiratory tract infections. They can damage the lining of the respiratory tract, including the throat, windpipe, and lungs.
Types
In general, M. pneumoniae infections are mild.
- Most common: Tracheobronchitis (chest cold)
- Less common: Pneumonia (lung infection)
Quick facts from a U.S. study
Symptoms
It can take 1 to 4 weeks for symptoms to appear after someone's been exposed to the bacteria. Symptoms can last for several weeks.
Some infected people may have no symptoms.
Symptoms depend on the type of infection.
Chest cold symptoms
Common symptoms include:
- Feeling tired
- Fever
- Headache
- Slowly worsening cough
- Sore throat
Younger children may have different symptoms
Instead of chest cold symptoms, children younger than 5 years old may have:
- Diarrhea
- Sneezing
- Sore throat
- Stuffy or runny nose
- Vomiting
- Watery eyes
- Wheezing
Pneumonia symptoms
People with pneumonia caused by M. pneumoniae can seem better than expected for someone with a lung infection. With mild symptoms, people may not stay home or in bed. Thus, the phrase "walking pneumonia" was coined.
Common symptoms include:
- Cough
- Feeling tired
- Fever and chills
- Shortness of breath
Complications
While uncommon, serious complications can occur that require hospital care.
M. pneumoniae infections can cause or make the following conditions worse:
- Asthma attacks or new asthma symptoms
- Encephalitis (swelling of the brain)
- Hemolytic anemia (too few red blood cells delivering oxygen)
- Renal dysfunction (kidney problems)
- Serious pneumonia
- Blistering skin disorders like reactive infectious mucocutaneous eruption (RIME)
Seek care for these symptoms
Seek medical care if you or your child has persistent or worsening symptoms of M. pneumoniae infection, such as wheezing. Seeking medical care is especially important for those at risk of developing severe disease.
Always seek medical care right away if you or your child is having difficulty breathing.
Causes and spread
People spread M. pneumoniae through coughing or sneezing. Some people are more likely to get infected than others.
Diagnosis
There's no quick way to test for M. pneumoniae infections, unlike some other respiratory illnesses. Instead, healthcare providers often examine the patient and look for signs. They may order a chest x-ray to see if the patient has pneumonia.
Many healthcare providers don't test for M. pneumoniae infection, especially for mild to moderate illness. If they do, they'll collect a specimen (usually a swab from the nose or throat) and send it to a lab.
Treatment and recovery
Most people with a mild M. pneumoniae infection will recover on their own without medicine. However, healthcare providers routinely treat pneumonia caused by M. pneumoniae with antibiotics.
Healthcare providers can use several types of antibiotics to treat people with pneumonia caused by M. pneumoniae.
Some M. pneumoniae are resistant to some antibiotics used for treatment. CDC has information on the potential danger of antibiotic resistance and how to prevent it.
- Diaz MH, Hersh AL, Olson J, et al. Mycoplasma pneumoniae Infections in Hospitalized Children — United States, 2018–2024. MMWR Morb Mortal Wkly Rep. 2025;74(23):394–400.
- Jain S, Williams DJ, Arnold SR, et al. Community-acquired pneumonia requiring hospitalization among U.S. children. N Engl J Med. 2015;372(9):835–45.
- Jain S, Self WH, Wunderink RG, et al. Community-acquired pneumonia requiring hospitalization among U.S. adults. N Engl J Med. 2015;373(5):415–27.