Lung Disease & Respiratory Health Center

Your doctor will usually diagnose pneumonia with:

• Your medical history.
• A physical exam.
• A chest X-ray, which is almost always done to check for changes in the lungs that may mean pneumonia and to look for other causes of your symptoms. But an X-ray does not always show whether you have pneumonia, especially if it is done when you first get sick. In some cases, the X-ray results may:
  • Suggest the type of organism (bacterial, viral, or fungal) causing pneumonia.
  • Show complications of pneumonia.
  • Show conditions that may occur with pneumonia, such as fluid in the chest cavity or a collapsed lung.
  • Reveal another condition, such as heart failure, lung cancer, or acute bronchitis.

Other tests

The need for more tests often depends on how severe your symptoms are, your age, and your overall health. In general, the sicker you are, the more tests you will have. This is especially true for older adults and infants.

Mucus test. If you are very ill, have severe shortness of breath, or have a condition that increases your risk (such as asthma or COPD), your doctor may test your mucus. Tests include a Gram stain and a sputum culture.

Rapid urine test. This test can identify some bacteria that cause pneumonia. This can help guide treatment for pneumonia.

HIV test. In people who have impaired immune systems, pneumonia may be caused by other organisms, including some forms of fungi, such as Pneumocystis jiroveci (formally called Pneumocystis carinii). This fungus often causes pneumonia in people who have AIDS. Some doctors may suggest an HIV test if they think that Pneumocystis jiroveci is causing the pneumonia.

If you have severe pneumonia, you may need other tests, including tests to check for complications and to find out how well your immune system is working.