Pneumonia is a bacterial, viral, or fungal infection of one or both sides of the lungs that causes the air sacs, or alveoli, of the lungs to fill up with fluid or pus. Symptoms can be mild or severe and may include a cough with phlegm (a slimy substance), fever, chills, and trouble breathing. Many factors affect how serious pneumonia is, such as type of germ causing the lung infection, age, and your overall health.
Pneumonia tends to be more serious for children under the age of five, adults over the age of 65, people with certain conditions such as heart failure, diabetes, or COPD (chronic obstructive pulmonary disease), or people who have weak immune systems due to HIV/AIDS, chemotherapy (a treatment for cancer), or organ or blood and marrow stem cell transplant procedures.
To diagnose pneumonia, your doctor will review your medical history, perform a physical exam, and order diagnostic tests. This information can help your doctor determine what type of pneumonia you have. If your doctor suspects you got your infection while in a hospital, you may be diagnosed with hospital-acquired pneumonia. If you have been on a ventilator to help you breathe, you may have ventilator-associated pneumonia.
The most common form of pneumonia is community-acquired pneumonia, which is when you get an infection outside of a hospital. Treatment depends on whether bacteria, viruses, or fungi are causing your pneumonia. If bacteria are causing your pneumonia, you usually are treated at home with oral antibiotics. Most people respond quickly to treatment.
If your symptoms worsen you should see a doctor right away. If you have severe symptoms or underlying health problems, you may need to be treated in a hospital. It may take several weeks to recover from pneumonia.
Bacteria, viruses, and fungi infections can cause pneumonia. These infections cause inflammation in the air sacs, or alveoli, of the lungs. This inflammation causes the air sacs to fill with fluid and pus.
This type of pneumonia sometimes is called Legionnaire's disease, and it has caused serious outbreaks. Outbreaks have been linked to exposure to cooling towers, whirlpool spas, and decorative fountains.
This is a common type of pneumonia that usually affects people younger than 40 years old. People who live or work in crowded places like schools, homeless shelters, and prisons are at higher risk for this type of pneumonia. It's usually mild and responds well to treatment with antibiotics.
This type of pneumonia can occur all year and often is mild. The infection is most common in people 65 to 79 years old.
Bacterial pneumonia can occur on its own or develop after you've had a viral cold or the flu. Bacterial pneumonia often affects just one lobe, or area, of a lung. When this happens, the condition is called lobar pneumonia.
Most of the time, the body filters bacteria 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 help stop the germs from reaching your lungs. Read How the Lungs Work for more information.
Sometimes bacteria manage to enter the lungs and cause infections. This is more likely to occur if:
When bacteria reach your lungs, your immune system goes into action. It sends many kinds of cells to attack the bacteria. These cells cause inflammation in alveoli (air sacs) and can cause these spaces to fill up with fluid and pus. This causes the symptoms of pneumonia.
Viruses that infect the respiratory tract may cause pneumonia. The influenza or flu virus is the most common cause of viral pneumonia in adults. Respiratory syncytial virus (RSV) is the most common cause of viral pneumonia in children younger than one year old. Other viruses can cause pneumonia such as the common cold virus known as rhinovirus, human parainfluenza virus (HPIV), and human metapneumovirus (HMPV).
Most cases of viral pneumonia are mild. They get better in about one to three 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.
Pneumocystis pneumonia is a serious fungal infection caused by Pneumocystis jirovecii. It occurs in people who have weak immune systems due to HIV/AIDS or the long-term use of medicines that suppress their immune systems, such as those used to treat cancer or as part of organ or blood and marrow stem cell transplant procedures.
Other fungal infections also can lead to pneumonia.
Your risk for pneumonia may increase if you have been exposed to certain chemicals, pollutants, or toxic fumes.
Other conditions and factors also increase your risk for pneumonia. Your risk also goes up if you:
Pneumonia can be very serious and even life threatening. Vaccines can help prevent certain types of pneumonia. Good hygiene, quitting smoking, and keeping your immune system strong by exercising and healthy eating are other ways to prevent pneumonia.
Vaccines are available to prevent pneumonia caused by pneumococcal bacteria or the flu virus, or influenza. Vaccines can't prevent all cases of infection. However, compared to people who don't get vaccinated, those who are vaccinated and still get pneumonia tend to have:
Because many people get pneumonia after having influenza or the flu, your yearly flu vaccine can help you and your family not get pneumonia. The flu vaccine is usually given in September through November before the months when influenza or the flu is most frequently spread.
Haemophilus influenzae type b (Hib) is a type of bacteria that can cause pneumonia and meningitis. The Hib vaccine is given to children to help prevent these infections. The vaccine is recommended for all children who are younger than five years old. The vaccine often is given to infants starting at two months of age.
You also can take the following steps to help prevent pneumonia:
See your doctor promptly if you have the following signs and symptoms:
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.
These painful or even potentially fatal complications can occur if pneumonia is not treated. The pleura is a membrane that consists of two large, thin layers of tissue. One layer wraps around the outside of your lungs and the other layer lines the inside of your chest cavity. Pleurisy is when the two layers of the pleura become irritated and inflamed, causing sharp pain each time you breathe in.
The pleural space is a very thin space between the two pleura. Pleural effusions are the build-up of fluid in the pleural space. If the fluid becomes infected, it is called empyema. If this happens, you may need to have the fluid drained through a chest tube or removed with surgery.
Sometimes pneumonia is hard to diagnose because it may cause symptoms commonly seen in people with colds 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.
Your doctor may be able to diagnose you with a certain type of pneumonia based on how you got your infection and the type of germ causing your infection.
Your doctor will ask about your signs and symptoms and how and when they began. To find out whether you have bacterial, viral, or fungal pneumonia, your doctor also may ask about:
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.
If your doctor thinks you have pneumonia, he or she may recommend one or more of the following tests.
Your doctor may recommend other tests if you're in the hospital, have serious symptoms, are older, or have other health problems.
Your doctor may collect a sample of sputum (spit) or phlegm (slimy substance from deep in your lungs) that was produced from one of your deep coughs and send the sample to the lab for testing. This may help your doctor find out if bacteria are causing your pneumonia. Then, he or she can plan your treatment.
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 to collect the fluid sample. The fluid is studied for bacteria that may cause pneumonia.
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.
CAP is the most common type of pneumonia and is usually caused by pneumococcus bacteria. Most cases occur during the winter. 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.
HAP is when people catch pneumonia during a hospital stay for another illness. 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 that are used to treat bacterial pneumonia.
VAP is when people who are on a ventilator machine to help them breathe get pneumonia.
Atypical pneumonia is a type of CAP. It is caused by lung infections with less common bacteria than the pneumococcus bacteria that cause CAP. Atypical bacteria include Legionella pneumophila, Mycoplasma pneumoniae, or Chlamydia pneumoniae.
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 lung abscesses.
Treatment for pneumonia depends on the type of pneumonia you have, the germ causing your infection, and how severe your pneumonia 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.
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.
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 one to three weeks.
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.
If you have pneumonia, follow your treatment plan, take all medicines as prescribed, and get follow-up medical care.
If you have pneumonia, you can take steps to recover from the infection and prevent complications.
It may take time to recover from pneumonia. Some people feel better and are able to return to their normal routines within a week. For other people, it can take a month or more. Most people continue to feel tired for about a month. Talk with your doctor about when you can go back to your normal routine.
If you have pneumonia, limit contact with family and friends. Cover your nose and mouth while coughing or sneezing, get rid of used tissues right away, and wash your hands. These actions help keep the infection from spreading to other people.