Pneumonia

Pneumonia (nu-MO-ne-ah) is an infection in one or both of the lungs. Many germs—such as bacteria, viruses, and fungi—can cause pneumonia.

The infection inflames your lungs' air sacs, which are called alveoli (al-VEE-uhl-eye). The air sacs may fill up with fluid or pus, causing symptoms such as a cough with phlegm (a slimy substance), fever, chills, and trouble breathing.

Overview

Pneumonia and its symptoms can vary from mild to severe. Many factors affect how serious pneumonia is, such as the type of germ causing the infection and your age and overall health.

Pneumonia tends to be more serious for:

Infants and young children.
Older adults (people 65 years or older).
People who have other health problems, such as heart failure, diabetes, or COPD (chronic obstructive pulmonary disease).
People who have weak immune systems as a result of diseases or other factors. Examples of these diseases and factors include HIV/AIDS, chemotherapy (a treatment for cancer), and an organ transplant or blood and marrow stem cell transplant.
Outlook

Pneumonia is common in the United States. Treatment for pneumonia depends on its cause, how severe your symptoms are, and your age and overall health. Many people can be treated at home, often with oral antibiotics.

Children usually start to feel better in 1 to 2 days. For adults, it usually takes 2 to 3 days. Anyone who has worsening symptoms should see a doctor.

People who have severe symptoms or underlying health problems may need treatment in a hospital. It may take 3 weeks or more before they can go back to their normal routines.

Fatigue (tiredness) from pneumonia can last for a month or more.

Types of Pneumonia

Pneumonia is named for the way in which a person gets the infection or for the germ that causes it.

Community-Acquired Pneumonia

Community-acquired pneumonia (CAP) occurs outside of hospitals and other health care settings. Most people get CAP by breathing in germs (especially while sleeping) that live in the mouth, nose, or throat.

CAP is the most common type of pneumonia. Most cases occur during the winter. About 4 million people get this form of pneumonia each year. About 1 out of every 5 people who has CAP needs to be treated in a hospital.

Hospital-Acquired Pneumonia

Some people catch pneumonia during a hospital stay for another illness. This is called hospital-acquired pneumonia (HAP). You're at higher risk of getting HAP if you're on a ventilator (a machine that helps you breathe).

HAP tends to be more serious than CAP because you're already sick. Also, hospitals tend to have more germs that are resistant to antibiotics (medicines used to treat pneumonia).

Health Care-Associated Pneumonia

Patients also may get pneumonia in other health care settings, such as nursing homes, dialysis centers, and outpatient clinics. This type of pneumonia is called health care-associated pneumonia.

Other Common Types of Pneumonia

Aspiration Pneumonia

This type of pneumonia can occur if you inhale food, drink, vomit, or saliva from your mouth into your lungs. This may happen if something disturbs your normal gag reflex, such as a brain injury, swallowing problem, or excessive use of alcohol or drugs.

Aspiration pneumonia can cause pus to form in a cavity in the lung. When this happens, it's called a lung abscess (AB-ses).

Atypical Pneumonia

Several types of bacteria—Legionella pneumophila, mycoplasma pneumonia, and Chlamydophila pneumoniae—cause atypical pneumonia, a type of CAP. Atypical pneumonia is passed from person to person.

What Causes Pneumonia?

Many germs can cause pneumonia. Examples include different kinds of bacteria, viruses, and, less often, fungi.

Most of the time, the body filters germs out of the air that we breathe to protect the lungs from infection. Your immune system, the shape of your nose and throat, your ability to cough, and fine, hair-like structures called cilia (SIL-e-ah) help stop the germs from reaching your lungs. (For more information, go to the Diseases and Conditions Index How the Lungs Work article.)

Sometimes, though, germs manage to enter the lungs and cause infections. This is more likely to occur if:

Your immune system is weak
A germ is very strong
Your body fails to filter germs out of the air that you breathe
For example, if you can't cough because you've had a stroke or are sedated, germs may remain in your airways. ("Sedated" means you're given medicine to make you sleepy.)

When germs reach your lungs, your immune system goes into action. It sends many kinds of cells to attack the germs. These cells cause the alveoli (air sacs) to become red and inflamed and to fill up with fluid and pus. This causes the symptoms of pneumonia.

Germs That Can Cause Pneumonia

Bacteria

Bacteria are the most common cause of pneumonia in adults. Some people, especially the elderly and those who are disabled, may get bacterial pneumonia after having the flu or even a common cold.

Many types of bacteria can cause pneumonia. Bacterial pneumonia can occur on its own or develop after you've had a cold or the flu. This type of pneumonia often affects one lobe, or area, of a lung. When this happens, the condition is called lobar pneumonia.

The most common cause of pneumonia in the United States is the bacterium Streptococcus (strep-to-KOK-us) pneumoniae, or pneumococcus (nu-mo-KOK-us).

Viruses

Respiratory viruses cause up to one-third of the pneumonia cases in the United States each year. These viruses are the most common cause of pneumonia in children younger than 5 years old.

Most cases of viral pneumonia are mild. They get better in about 1 to 3 weeks without treatment. Some cases are more serious and may require treatment in a hospital.

If you have viral pneumonia, you run the risk of getting bacterial pneumonia as well.

The flu virus is the most common cause of viral pneumonia in adults. Other viruses that cause pneumonia include respiratory syncytial virus, rhinovirus, herpes simplex virus, severe acute respiratory syndrome (SARS), and more.

Fungi

Three types of fungi in the soil in some parts of the United States can cause pneumonia. These fungi are:

Coccidioidomycosis (kok-sid-e-OY-do-mi-KO-sis). This fungus is found in Southern California and the desert Southwest.
Histoplasmosis (HIS-to-plaz-MO-sis). This fungus is found in the Ohio and Mississippi River Valleys.
Cryptococcus (krip-to-KOK-us). This fungus is found throughout the United States in bird droppings and soil contaminated with bird droppings.
Most people exposed to these fungi don't get sick, but some do and require treatment.

Serious fungal infections are most common in people who have weak immune systems due to the long-term use of medicines to suppress their immune systems or having HIV/AIDS.

Pneumocystis jiroveci (nu-mo-SIS-tis ye-RO-VECH-e), formerly Pneumocystis carinii, sometimes is considered a fungal pneumonia. However, it's not treated with the usual antifungal medicines. This type of infection is most common in people who:

Have HIV/AIDS or cancer
Have had an organ transplant and/or blood and marrow stem cell transplant
Take medicines that affect their immune systems
Other kinds of fungal infections also can lead to pneumonia.
What Are the Signs and Symptoms of Pneumonia?

The signs and symptoms of pneumonia vary from mild to severe. Many factors affect how serious pneumonia is, including the type of germ causing the infection and your age and overall health. (For more information, go to "Who Is at Risk for Pneumonia?")

See your doctor promptly if you:

Have a high fever
Have shaking chills
Have a cough with phlegm (a slimy substance), which doesn't improve or worsens
Develop shortness of breath with normal daily activities
Have chest pain when you breathe or cough
Feel suddenly worse after a cold or the flu
People who have pneumonia may have other symptoms, including nausea (feeling sick to the stomach), vomiting, and diarrhea.

Symptoms may vary in certain populations. Newborns and infants may not show any signs of the infection. Or, they may vomit, have a fever and cough, or appear restless, sick, or tired and without energy.

Older adults and people who have serious illnesses or weak immune systems may have fewer and milder symptoms. They may even have a lower than normal temperature. If they already have a lung disease, it may get worse. Older adults who have pneumonia sometimes have sudden changes in mental awareness.

Complications of Pneumonia

Often, people who have pneumonia can be successfully treated and not have complications. But some people, especially those in high-risk groups, may have complications such as:

Bacteremia (bak-ter-E-me-ah). This serious complication occurs if the infection moves into your bloodstream. From there, it can quickly spread to other organs, including your brain.
Lung abscesses. An abscess occurs if pus forms in a cavity in the lung. An abscess usually is treated with antibiotics. Sometimes surgery or drainage with a needle is needed to remove the pus.
Pleural effusion. Pneumonia may cause fluid to build up in the pleural space. This is a very thin space between two layers of tissue that line the lungs and the chest cavity. Pneumonia can cause the fluid to become infected—a condition called empyema (em-pi-E-ma). If this happens, you may need to have the fluid drained through a chest tube or removed with surgery.
How Is Pneumonia Diagnosed?

Pneumonia can be hard to diagnose because it may seem like a cold or the flu. You may not realize it's more serious until it lasts longer than these other conditions.

Your doctor will diagnose pneumonia based on your medical history, a physical exam, and test results.

Medical History

Your doctor will ask about your signs and symptoms and how and when they began. To find out what type of germ is causing the pneumonia, he or she also may ask about:

Any recent traveling you've done
Your hobbies
Your exposure to animals
Your exposure to sick people at home, school, or work
Your past and current medical conditions, and whether any have gotten worse recently
Any medicines you take
Whether you smoke
Whether you've had flu or pneumonia vaccinations
Physical Exam

Your doctor will listen to your lungs with a stethoscope. If you have pneumonia, your lungs may make crackling, bubbling, and rumbling sounds when you inhale. Your doctor also may hear wheezing.

Your doctor may find it hard to hear sounds of breathing in some areas of your chest.

Diagnostic Tests

If your doctor thinks you have pneumonia, he or she may recommend one or more of the following tests.

Chest X Ray

A chest x ray is a painless test that creates pictures of the structures inside your chest, such as your heart, lungs, and blood vessels.

A chest x ray is the best test for diagnosing pneumonia. However, this test won't tell your doctor what kind of germ is causing the pneumonia.

Blood Tests

Blood tests involve taking a sample of blood from a vein in your body. A complete blood count (CBC) measures many parts of your blood, including the number of white blood cells in the blood sample. The number of white blood cells can show whether you have a bacterial infection.

Your doctor also may recommend a blood culture to find out whether the infection has spread to your bloodstream. This test is used to detect germs in the bloodstream. A blood culture may show which germ caused the infection. If so, your doctor can decide how to treat the infection.

Other Tests

Your doctor may recommend other tests if you're in the hospital, have serious symptoms, are older, or have other health problems.

Sputum test. Your doctor may look at a sample of sputum (spit) collected from you after a deep cough. This may help your doctor find out what germ is causing your pneumonia. Then, he or she can plan treatment.

Chest computed tomography (CT) scan. A chest CT scan is a painless test that creates precise pictures of the structures in your chest, such as your lungs. A chest CT scan is a type of x ray, but its pictures show more detail than those of a standard chest x ray.

Pleural fluid culture. For this test, a fluid sample is taken from the pleural space (a thin space between two layers of tissue that line the lungs and chest cavity). Doctors use a procedure called thoracentesis (THOR-ah-sen-TE-sis) to collect the fluid sample. The fluid is studied for germs that may cause pneumonia.

Pulse oximetry. For this test, a small sensor is attached to your finger or ear. The sensor uses light to estimate how much oxygen is in your blood. Pneumonia can keep your lungs from moving enough oxygen into your bloodstream.

If you're very sick, your doctor may need to measure the level of oxygen in your blood using a blood sample. The sample is taken from an artery, usually in your wrist. This test is called an arterial blood gas test.

Bronchoscopy. Bronchoscopy (bron-KOS-ko-pee) is a procedure used to look inside the lungs' airways. If you're in the hospital and treatment with antibiotics isn't working well, your doctor may use this procedure.

Your doctor passes a thin, flexible tube through your nose or mouth, down your throat, and into the airways. The tube has a light and small camera that allow your doctor to see your windpipe and airways and take pictures.

How Is Pneumonia Treated?

Treatment for pneumonia depends on the type of pneumonia you have and how severe it is. Most people who have community-acquired pneumonia—the most common type of pneumonia—are treated at home.

The goals of treatment are to cure the infection and prevent complications.

General Treatment

If you have pneumonia, follow your treatment plan, take all medicines as prescribed, and get ongoing medical care. Ask your doctor when you should schedule followup care. Your doctor may want you to have a chest x ray to make sure the pneumonia is gone.

Although you may start feeling better after a few days or weeks, fatigue (tiredness) can persist for up to a month or more. People who are treated in the hospital may need at least 3 weeks before they can go back to their normal routines.

Bacterial Pneumonia

Bacterial pneumonia is treated with medicines called antibiotics. You should take antibiotics as your doctor prescribes. You may start to feel better before you finish the medicine, but you should continue taking it as prescribed. If you stop too soon, the pneumonia may come back.

Most people begin to improve after 1 to 3 days of antibiotic treatment. This means that they should feel better and have fewer symptoms, such as cough and fever.

Viral Pneumonia

Antibiotics don't work when the cause of pneumonia is a virus. If you have viral pneumonia, your doctor may prescribe an antiviral medicine to treat it.

Viral pneumonia usually improves in 1 to 3 weeks.

Treating Severe Symptoms

You may need to be treated in a hospital if:

Your symptoms are severe
You're at risk for complications because of other health problems
If the level of oxygen in your bloodstream is low, you may receive oxygen therapy. If you have bacterial pneumonia, your doctor may give you antibiotics through an intravenous (IV) line inserted into a vein.
How Can Pneumonia Be Prevented?

Pneumonia can be very serious and even life threatening. When possible, take steps to prevent the infection, especially if you're in a high-risk group.

Vaccines

Vaccines are available to prevent pneumococcal pneumonia and the flu. Vaccines can't prevent all cases of infection. However, compared to people who don't get vaccinated, those who do and still get pneumonia tend to have:

Milder cases of the infection
Pneumonia that doesn't last as long
Fewer serious complications
Pneumococcal Pneumonia Vaccine

A vaccine is available to prevent pneumococcal pneumonia. In most adults, one shot is good for at least 5 years of protection. This vaccine often is recommended for:

People who are 65 years old or older.
People who have chronic (ongoing) diseases, serious long-term health problems, or weak immune systems. For example, this may include people who have cancer, HIV/AIDS, asthma, or damaged or removed spleens.
People who smoke.
Children who are younger than 5 years old.
Children who are 5–18 years of age with certain medical conditions, such as heart or lung diseases or cancer. For more information, talk with your child's doctor.
For more information about the pneumococcal pneumonia vaccine, go to the Centers for Disease Control and Prevention's (CDC's) Vaccines and Preventable Diseases: Pneumococcal Vaccination Web page.

Influenza Vaccine

The vaccine that helps prevent the flu is good for 1 year. It's usually given in October or November, before peak flu season.

Because many people get pneumonia after having the flu, this vaccine also helps prevent pneumonia.

For more information about the influenza vaccine, go to the CDC's Vaccines and Preventable Diseases: Seasonal Influenza (Flu) Vaccination Web page.

Hib Vaccine

Haemophilus influenzae type b (Hib) is a type of bacteria that can cause pneumonia and meningitis (men-in-JI-tis). (Meningitis is an infection of the covering of the brain and spinal cord.) The Hib vaccine is given to children to help prevent these infections.

The vaccine is recommended for all children in the United States who are younger than 5 years old. The vaccine often is given to infants starting at 2 months of age.

For more information about the Hib vaccine, go to the CDC's Vaccines and Preventable Diseases: Hib Vaccination Web page.

Other Ways To Help Prevent Pneumonia

You also can take the following steps to help prevent pneumonia:

Wash your hands with soap and water or alcohol-based rubs to kill germs.
Don't smoke. Smoking damages your lungs' ability to filter out and defend against germs. For information about how to quit smoking, go to the Health Topics Smoking and Your Heart article. Although this resource focuses on heart health, it includes general information about how to quit smoking.
Keep your immune system strong. Get plenty of rest and physical activity and follow a healthy diet.
If you have pneumonia, limit contact with family and friends. Cover your nose and mouth while coughing or sneezing, and get rid of used tissues right away. These actions help keep the infection from spreading.