What Is Pneumonia?
Pneumonia is an infection of the lungs. The air sacs in the lungs (called alveoli) fill up with pus and other fluid, which makes it hard for oxygen to reach the bloodstream.
Someone with pneumonia may have a fever, cough, or trouble breathing.
What Are the Signs & Symptoms of Pneumonia?
Symptoms vary depending on a person's age and what caused the pneumonia, but can include:
- very fast breathing (in some cases, this is the only symptom)
- breathing with grunting or wheezing sounds
- working hard to breathe; this can include flaring of the nostrils, belly breathing, or movement of the muscles between the ribs
- fever
- cough
- stuffy nose
- shaking chills
- vomiting
- chest pain
- abdominal pain (because a child is coughing and working hard to breathe)
- less activity
- loss of appetite (in older kids) or poor feeding (in infants), which may lead to dehydration
- in extreme cases, bluish or gray color of the lips and fingernails
If the pneumonia is in the lower part of the lungs near the abdomen, a person might have a fever and abdominal pain or vomiting but no breathing problems.
What Causes Pneumonia?
Pneumonia is caused by a variety of germs (viruses, bacteria, fungi, and parasites). Most cases, though, are caused by viruses. These include adenoviruses, rhinovirus, influenza virus (flu), respiratory syncytial virus (RSV), and parainfluenza virus (which also can cause croup).
Often, pneumonia begins after an upper respiratory tract infection (an infection of the nose and throat), with symptoms starting after 2 or 3 days of a cold or sore throat. It then moves to the lungs. Fluid, white blood cells, and debris start to gather in the air spaces of the lungs and block the smooth passage of air, making it harder for the lungs to work well.
Kids with pneumonia caused by bacteria usually become sick fairly quickly, starting with a sudden high fever and unusually fast breathing.
Kids with pneumonia caused by viruses probably will have symptoms that appear more gradually and are less severe, though wheezing can be more common.
Some symptoms give important clues about which germ is causing the pneumonia. For example, in older kids and teens, pneumonia due to Mycoplasma (also called walking pneumonia) is very common and causes a sore throat, headache, and rash in addition to the usual symptoms of pneumonia.
In babies, pneumonia due to chlamydia may cause conjunctivitis (pinkeye) with only mild illness and no fever. When pneumonia is due to whooping cough (pertussis), a child may have long coughing spells, turn blue from lack of air, or make the classic "whoop" sound when trying to take a breath. Fortunately, the pertussis vaccine can help protect kids against whooping cough.
The length of time between exposure to the germ and when someone starts feeling sick varies, depending on which virus or bacteria is causing the pneumonia (for instance, 4 to 6 days for RSV, but just 18 to 72 hours for the flu).
How Is Pneumonia Diagnosed?
Doctors usually make a pneumonia diagnosis after a physical examination. They'll check a child's appearance, breathing pattern, and vital signs, and listen to the lungs for abnormal sounds. They might order a chest X-ray or blood tests, but neither are necessary to make the diagnosis.