About Mycoplasma pneumoniae Infection

Key points

  • Bacteria called Mycoplasma pneumoniae can cause respiratory tract infections.
  • These infections are generally mild but sometimes can be severe.
  • Most will recover without medicine, but some people need antibiotics to get better.
  • Call a healthcare provider about difficulty breathing or symptoms that concern you.
A young boy covers his cough in his elbow while leaving school.

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.


In general, M. pneumoniae infections are mild.

  • Most common: Tracheobronchitis (chest cold)
  • Less common: Pneumonia (lung infection)

Quick facts from a U.S. study‎

When people need hospital care due to pneumonia, M. pneumoniae are a common bacterial cause of the infection. For children, they're the most common cause and, for adults, the second most common cause.


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

Common symptoms include:

  • Cough
  • Feeling tired
  • Fever and chills
  • Shortness of breath

M. pneumoniae can cause "walking pneumonia"‎

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.


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
  • Skin disorders like Stevens-Johnson syndrome

Causes and spread

People spread M. pneumoniae through coughing or sneezing. Some people are more likely to get infected than others.


Hand washing and covering coughs and sneezes can help prevent spreading these bacteria.

Keep Reading: How to Prevent Spread


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.

Most healthcare providers don't test for M. pneumoniae infection. If they do, they'll collect a specimen and send it to a lab. The types of specimens that can be collected include:

  • Most common: A swab from the nose or throat
  • Least common: Blood

Treatment and recovery

Most people with a mild M. pneumoniae infection will recover on their own without medicine.

Ask about symptom relief‎

Ask a healthcare provider or pharmacist about over-the-counter medicines to help you feel better while you're recovering.

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.