Pneumonia - adults (community acquired)


Pneumonia is a breathing (respiratory) condition in which there is an infection of the lung.

This article covers pneumonia in people who have not recently been in the hospital or another health care facility (nursing home or rehab facility). This type of pneumonia is called community-acquired pneumonia, or CAP.

See also: Hospital-acquired pneumonia

Alternative Names

Bronchopneumonia; Community-acquired pneumonia; CAP


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.

Ways you can get pneumonia include:

Pneumonia caused by bacteria tends to be the most serious kind. In adults, bacteria are the most common cause of pneumonia.

Many other bacteria can also cause pneumonia.

Viruses are also a common cause of pneumonia, especially in infants and young children.

Risk factors that increase your chances of getting pneumonia include:


The most common symptoms of pneumonia are:

Other symptoms include:

Exams and Tests

If you have pneumonia, you may be working hard to breathe, or breathing fast.

The health care provider will hear crackles or abnormal breath sounds when listening to your chest with a stethoscope. Other abnormal breathing sounds may also be heard through the stethoscope or by tapping on your chest wall (percussion).

The health care provider will likely order a chest x-ray if pneumonia is suspected.

You may need other tests, including:

Less often patients may need:


Your doctor must first decide whether you need to be in the hospital. If you are treated in the hospital, you will receive:

It is very important that you are started on antibiotics very soon after you are admitted (unless you have viral pneumonia).

You are more likely to be admitted to the hospital if you:

However, many people can be treated at home. Your doctor may tell you to take antibiotics. Antibiotics help some people with pneumonia get better.

Breathing warm, moist (wet) air helps loosen the sticky mucus that may make you feel like you are choking. These things may help:

Drink plenty of liquids (as long as your health care provider says it is okay):

Get plenty of rest when you go home. If you have trouble sleeping at night, take naps during the day.

Outlook (Prognosis)

With treatment, most patients will improve within 2 weeks. Elderly or very sick patients may need longer treatment.

Those who may be more likely to have complicated pneumonia include:

In rare cases, more severe problems may develop, including:

Your doctor may want to make sure your chest x-ray becomes normal again after you are treated. However, it may take many weeks for your x-ray to clear up.

When to Contact a Medical Professional

Call your doctor if you have:


Wash your hands often, especially after:

Also wash your hands before eating or preparing foods.

Don't smoke. Tobacco damages your lung's ability to ward off infection.

Vaccines may help prevent some types of pneumonia. They are even more important for the elderly and people with diabetes, asthma, emphysema, HIV, cancer, or other long-term conditions:

If you have cancer or HIV, talk to your doctor about ways to prevent pneumonia and other infections.


Centers for Disease Control and Prevention. Recommended adult immunization schedule--United States, 2012. MMWR. 2012;61(4)

Limper AH. Overview of pneumonia. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier;2011:chap 97.

Niederman M. In the clinic. Community-acquired pneumonia. Ann Intern Med. 2009;151(7).

Torres A, Menandez R, Wunderink R. Pyogenic bacterial pneumonia and lung abscess. In: Mason RJ, Broaddus VC, Martin TR, et al. Murray & Nadel's Textbook of Respiratory Medicine. 5th ed. Philadelphia, Pa: Saunders Elsevier; 2010:chap 32.

Review Date: 5/29/2012
Reviewed By: Denis Hadjiliadis, MD, Assistant Professor of Medicine, Division of Pulmonary, Allergy and Critical Care. University of Pennsylvania, Philadelphia, PA. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.
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