The signs and symptoms of pneumonia vary from mild to severe, depending upon factors such as the type of germ causing the infection and your age and overall health. Mild signs and symptoms often are similar to those of a cold or flu, but they last longer.
Signs and symptoms of pneumonia include:
- Fever, sweating and shaking chills
- Lower than normal body temperature in people older than age 65, and in people with poor overall health or weakened immune systems
- Cough, which may produce thick, sticky fluid
- Chest pain when you breathe deeply or cough
- Shortness of breath
- Fatigue and muscle aches
- Nausea, vomiting or diarrhea
Newborns and infants may not show any sign of the infection. Or they may vomit, have a fever and cough, appear restless or tired and without energy, or have difficulty breathing and eating.
Older people who have pneumonia sometimes have sudden changes in mental awareness.
When to see a doctor
See your doctor if you have difficulty breathing, chest pain, persistent fever of 102 F (39 C) or higher or persistent cough, especially if you are coughing up pus.
It's especially important to see a doctor if:
- A child with signs and symptoms is younger than age 2
- You are older than age 65
- You have an underlying health condition or weakened immune system
- You're having chemotherapy or taking medication that suppresses your immune system
For some older adults and people with heart failure or lung ailments, pneumonia can quickly become a life-threatening condition.
Pneumonia has many possible causes. The most common are bacteria and viruses in the air we breathe. Your body usually prevents these germs from infecting your lungs. But sometimes these germs can overpower your immune system, even if your health is generally good.
Pneumonia is classified according to the types of germs that cause it, and where you acquired the infection.
Community-acquired pneumonia is the most common type of pneumonia. It occurs outside of hospitals and other health care facilities, and may be caused by:
- Bacteria, such as Streptococcus pneumoniae. Bacterial community-acquired pneumonia can occur on its own or after you have a cold or respiratory flu. This type of pneumonia often affects one area (lobe) of the lung, a condition called lobar pneumonia.
- Bacteria-like organisms, such as Mycoplasma pneumoniae, which typically produce milder signs and symptoms than do other types of pneumonia. "Walking pneumonia," a term used to describe pneumonia that isn't severe enough to require bed rest, may result from Mycoplasma pneumoniae.
- Viruses, including some that are the same type of viruses that cause colds and flu. Viruses are the most common cause of pneumonia in children younger than 2 years. Viral pneumonia is usually mild. But viral pneumonia caused by certain influenza viruses, such as sudden acute respiratory syndrome (SARS), can become very serious.
- Fungi, which can be found in soil and in bird droppings. This type of pneumonia is most common in people with an underlying health problem or weakened immune system and in people who have inhaled a large dose of the organisms.
Hospital-acquired pneumonia is a bacterial infection that occurs in people 48 hours or more after being hospitalized for another condition. Hospital-acquired pneumonia can be serious because the bacteria causing it may be more resistant to antibiotics.
People who are on a breathing machine (ventilator), often used in intensive care units, are at higher risk of this type of pneumonia.
Health care-acquired pneumonia
Health care-acquired pneumonia is a bacterial infection that occurs in people who are living in long-term care facilities or have been treated in outpatient clinics, including kidney dialysis centers. Like hospital-acquired pneumonia, health care-acquired pneumonia can be caused by bacteria more resistant to antibiotics.
Aspiration pneumonia occurs when you inhale food, drink, vomit or saliva into your lungs. This aspiration may happen if something disturbs your normal gag reflex, such as a brain injury, swallowing problem, or excessive use of alcohol or drugs.
Pneumonia can affect anyone. But the two age groups at highest risk are:
- Infants and children younger than age 2 years, because their immune systems are still developing
- People older than age 65
Other risk factors include:
- Certain chronic diseases, such as asthma, chronic obstructive pulmonary disease and heart disease
- Weakened or suppressed immune system, due to factors such as HIV/AIDS, organ transplant, chemotherapy for cancer or long-term steroid use
- Smoking, which damages your body's natural defenses against the bacteria and viruses that cause pneumonia
- Being placed on a ventilator while hospitalized
Often, people who have pneumonia can be treated successfully with medication.But some people, especially those in high-risk groups, may experience complications, including:
- Bacteria in the bloodstream (bacteremia). Bacteria that enter the bloodstream from your lungs can spread the infection to other organs, potentially causing organ failure.
- Lung abscess. An abscess occurs if pus forms in a cavity in the lung. An abscess is usually treated with antibiotics. Sometimes, surgery or drainage with a long needle or tube placed into the abscess is needed to remove the pus.
- Fluid accumulation around your lungs (pleural effusion). Pneumonia may cause fluid to build up in the thin space between layers of tissue that line the lungs and chest cavity (pleura). If the fluid becomes infected, you may need to have it drained through a chest tube or removed with surgery.
- Difficulty breathing. If your pneumonia is severe or you have chronic underlying lung diseases, you may have trouble breathing in enough oxygen. You may need to be hospitalized and use a mechanical ventilator while your lung heals.
To help prevent pneumonia:
- Get a seasonal flu shot. The influenza virus can be a direct cause of viral pneumonia. Bacterial pneumonia is also a common complication of the flu. A yearly flu shot provides significant protection.
- Get a pneumonia vaccination. Doctors recommend a one-time vaccine against Streptococcus pneumoniae bacteria (pneumococcus) for everyone older than age 65, as well as for people of any age residing in nursing homes and long-term care facilities, and for smokers. The vaccine is especially recommended for anyone at high risk of pneumococcal pneumonia. Some doctors recommend a booster shot five years after the first dose.
- Have your child vaccinated. Doctors recommend a different pneumonia vaccine for all children younger than age 2 and for children ages 2 to 5 years who are at particular risk of pneumococcal disease. Children who attend a group day care center should also get the vaccine. Doctors also recommend seasonal flu shots for children older than six months.
- Practice good hygiene. To protect yourself against ordinary respiratory infections that sometimes lead to pneumonia, wash your hands regularly or use an alcohol-based hand sanitizer.
- Don't smoke. Smoking damages your lungs' natural defenses against respiratory infections.
- Stay rested and fit. Proper rest, a healthy diet and moderate exercise can help keep your immune system strong.
- Set an example. Stay home when you're sick. When you're in public and have a cold, catch your coughs and sneezes in the inner crook of your elbow.