Pneumonia - adults (community acquired)
Bronchopneumonia; Community-acquired pneumonia; CAP
Pneumonia is a breathing (respiratory) condition in which there is an infection of the lung.
This article covers community-acquired pneumonia (CAP). This type of pneumonia is found in people who have not recently been in the hospital or another health care facility such as a nursing home or rehab facility. Pneumonia that affects people in health care facilities, such as hospitals, is called hospital-acquired pneumonia (or health care-associated pneumonia).
Pneumonia is a common illness that affects millions of people each year in the United States. Germs called bacteria, viruses, and fungi may cause pneumonia. In adults, bacteria are the most common cause of pneumonia.
Ways you can get pneumonia include:
- Bacteria and viruses living in your nose, sinuses, or mouth may spread to your lungs.
- You may breathe some of these germs directly into your lungs.
- You breathe in (inhale) food, liquids, vomit, or fluids from the mouth into your lungs (aspiration pneumonia).
Pneumonia can be caused by many types of germs.
- The most common type of bacteria is Streptococcus pneumoniae (pneumococcus).
- Atypical pneumonia, often called walking pneumonia, is caused by other bacteria.
- A fungus called Pneumocystis jiroveci can cause pneumonia in people whose immune system is not working well, especially people with advanced HIV infection.
- Viruses, such as the flu virus, and most recently SARS-CoV-2 (which causes COVID-19), are also common causes of pneumonia.
Risk factors that increase your chance of getting pneumonia include:
- Chronic lung disease (COPD, bronchiectasis, cystic fibrosis)
- Cigarette smoking
- Dementia, stroke, brain injury, cerebral palsy, or other brain disorders
- Immune system problem (during cancer treatment, or due to HIV/AIDS, organ transplant, or other diseases)
- Other serious illnesses, such as heart disease, liver cirrhosis, or diabetes
- Recent surgery or trauma
- Surgery to treat cancer of the mouth, throat, or neck
Everyone coughs from time to time. You might pick up a cold, have an allergy, or just get a tickle from something irritating your throat. But if you're really hacking and coughing up yellow or green mucus, and you've also got a fever, chills, and shortness of breath, you may have picked up a more serious infection, called pneumonia. And sometimes pneumonia's symptoms aren't as obvious. Pneumonia is caused by an infection in your lung. Bacteria or viruses like these can sometimes get into your lungs through your nose or mouth and make you sick. You're more likely to get pneumonia if you've got a problem with your immune system that makes it harder to fight off infections. You're also at greater risk if you've got a lung disease like COPD or cystic fibrosis, you've recently had the flu, or you're exposed to cigarette smoke. People who live in nursing homes are also more likely to get pneumonia. With pneumonia, you may cough up greenish or yellow phlegm. You also may run a fever and have the chills. Pneumonia can make it hard to breathe. You may feel like you've run up a flight of stairs when you were just sitting still. Your doctor can tell that you have pneumonia and not just a cold by listening with a stethoscope for crackle sounds in your chest. You may need a chest x-ray or blood tests to know for sure that you have pneumonia. If bacteria caused your pneumonia, your doctor can give you antibiotics, drugs that kill bacteria. Keep taking the antibiotic until you finish the whole prescription so you don't re-infect yourself. To help loosen all of that mucus clogging your lungs, breathe in the warm mist from a humidifier and drink plenty of water. Take it easy too. Don't try to run back to work and infect everyone else. Rest until you feel better. Whatever you do, don't smoke, it will only make your pneumonia worse. If your pneumonia is really severe or you have another serious health problem, your doctor may recommend that you get treated in the hospital. While there, you'll get antibiotics and fluids through a vein. You may also be given oxygen to help you breathe easier. The best way to deal with pneumonia is to avoid getting it in the first place. Older adults, children, and people with serious conditions like diabetes, asthma, cancer, and emphysema should talk to their doctor about getting vaccinated against pneumonia and the illnesses that cause it. Once you get treated, your pneumonia should clear up within a couple of weeks. Your doctor may want to check your lungs to make sure they're clear. Sometimes pneumonia can lead to serious lung complications, so call your doctor right away if your breathing problems get worse, you have chest pain, or you cough up blood.
The most common symptoms of pneumonia are:
- Cough (with some pneumonias you may cough up greenish or yellow mucus, or even bloody mucus)
- Fever, which may be mild or high
- Shaking chills
- Shortness of breath (may only occur when you climb stairs or exert yourself)
Other symptoms include:
- Confusion, especially in older people
- Excess sweating and clammy skin
- Loss of appetite, low energy, and fatigue
- Malaise (not feeling well)
- Sharp or stabbing chest pain that gets worse when you breathe deeply or cough
- White nail syndrome, or leukonychia
Exams and Tests
The health care provider will listen for crackles or abnormal breath sounds when listening to your chest with a stethoscope. Tapping on your chest wall (percussion) helps the provider listen and feel for abnormal sounds in your chest.
If pneumonia is suspected, the provider will likely order a chest x-ray.
Other tests that may be ordered include:
- Arterial blood gases to see if enough oxygen is getting into your blood from the lungs.
- Blood and sputum cultures to look for the germ that may be causing the pneumonia.
- CBC to check white blood cell count.
- CT scan of the chest.
- Bronchoscopy. A flexible tube with a lighted camera on the end passed down to your lungs, in selected cases.
- Thoracentesis. Removing fluid from the space between the outside lining of the lungs and the chest wall.
- Nasopharyngeal swab to assess for viruses like influenza and SARS-CoV-2.
Your provider must first decide whether you need to be in the hospital. If you are treated in the hospital, you will receive:
- Fluids and antibiotics through your veins
- Oxygen therapy
- Breathing treatments (possibly)
If you are diagnosed with a bacterial form of pneumonia, it is important that you are started on antibiotics very soon after you are admitted. If you have viral pneumonia, you will not receive antibiotics. This is because antibiotics do not kill viruses. You may receive other medicines, such as antivirals, if you have the flu.
You are more likely to be admitted to the hospital if you:
- Have another serious medical problem
- Have severe symptoms
- Are unable to care for yourself at home, or are unable to eat or drink
- Are older than 65
- Have been taking antibiotics at home and are not getting better
Many people can be treated at home. If so, your provider may tell you to take medicines such as antibiotics.
When taking antibiotics:
- Do not miss any doses. Take the medicine until it is gone, even when you start to feel better.
- Do not take cough medicine or cold medicine unless your doctor says it is OK. Coughing helps your body get rid of mucus from your lungs.
Breathing warm, moist (wet) air helps loosen the sticky mucus that may make you feel like you are choking. These things may help:
- Place a warm, wet washcloth loosely over your nose and mouth.
- Fill a humidifier with warm water and breathe in the warm mist.
- Take a couple of deep breaths 2 or 3 times every hour. Deep breaths will help open up your lungs.
- Tap your chest gently a few times a day while lying with your head lower than your chest. This helps bring up mucus from the lungs so that you can cough it out.
Drink plenty of liquids, as long as your provider says it is OK.
- Drink water, juice, or weak tea
- Drink at least 6 to 10 cups (1.5 to 2.5 liters) a day
- Do not drink alcohol
Get plenty of rest when you go home. If you have trouble sleeping at night, take naps during the day.
With treatment, most people improve within 2 weeks. Older adults or very sick people may need longer treatment.
Those who may be more likely to have complicated pneumonia include:
- Older adults
- People whose immune system does not work well
- People with other, serious medical problems such as diabetes or cirrhosis of the liver
In all of the above conditions, pneumonia can lead to death, if it is severe.
In rare cases, more serious problems may develop, including:
- Life-threatening changes in the lungs that require a breathing machine
- Fluid around the lung (pleural effusion)
- Infected fluid around the lung (empyema)
- Lung abscesses
Your provider may order another x-ray. This is to make sure your lungs are clear. But it may take many weeks for your x-ray to clear up. You will likely feel better before the x-ray clears up.
When to Contact a Medical Professional
Call your provider if you have:
- Cough that brings up bloody or rust-colored mucus
- Breathing (respiratory) symptoms that get worse
- Chest pain that gets worse when you cough or breathe in
- Fast or painful breathing
- Night sweats or unexplained weight loss
- Shortness of breath, shaking chills, or persistent fevers
- Signs of pneumonia and a weak immune system (for example, such as with HIV or chemotherapy)
- Worsening of symptoms after initial improvement
You can help prevent pneumonia by following the measures below.
Wash your hands often, especially:
- Before preparing and eating food
- After blowing your nose
- After going to the bathroom
- After changing a baby's diaper
- After coming in contact with people who are sick
Avoid coming into contact with people who are sick.
Do not smoke. Tobacco damages your lung's ability to fight infection.
Vaccines may help prevent some types of pneumonia. Be sure to get the following vaccines:
- Flu vaccine can help prevent pneumonia caused by the flu virus.
- Pneumococcal vaccine lowers your chances of getting pneumonia from Streptococcus pneumoniae.
Vaccines are even more important for older adults and people with diabetes, asthma, emphysema, HIV, cancer, people with organ transplants, or other long-term conditions.
Daly JS, Ellison RT. Acute pneumonia. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 67.
Musher DM. Overview of pneumonia. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 91.
Wunderunk RG. Guidelines to manage community-acquired pneumonia. Clin Chest Med. 2018;39(4):723-731. PMID: 30390744
Last reviewed on: 8/3/2020
Reviewed by: Denis Hadjiliadis, MD, MHS, Paul F. Harron Jr. Associate Professor of Medicine, Pulmonary, Allergy, and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.