Signs and Symptoms

Infections caused by Mycoplasma pneumoniae are generally mild but sometimes can be severe. Once someone becomes infected with the bacteria, symptoms usually appear after 1 to 4 weeks. Symptoms can last for several weeks.

Symptoms depend on the type of infection.

A grandmother reading to her sick grandson

Children who get Mycoplasma pneumoniae infection usually have signs of a chest cold


The most common type of infection is tracheobronchitis (chest cold).

Common symptoms of a chest cold include:

  • Sore throat
  • Feeling tired
  • Fever
  • Slowly worsening cough
  • Headache


Pneumonia (lung infection) can sometimes occur.

Common symptoms of pneumonia include:

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

People with pneumonia caused by M. pneumoniae can seem better than expected for someone with a lung infection. With mild symptoms taken to be a cold, they may not stay home or in bed. Thus, the phrase “walking pneumonia” was coined.

Symptoms in young children

Children younger than 5 years old who get M. pneumoniae infection could have symptoms that are different from older children and adults. Instead, they may have the following symptoms:

  • Sneezing
  • Stuffy or runny nose
  • Sore throat
  • Watery eyes
  • Wheezing
  • Vomiting
  • Diarrhea


When to seek medical attention

Call a healthcare provider if you or your child has difficulty breathing or symptoms that concern you.