Table of Contents
What is pneumocystis pneumonia (PCP)?
Pneumocystis pneumonia (PCP) is a kind of pneumonia caused by a fungus called Pneumocystis jirovecior, or P. jiroveci. It used to be called Pneumocystis carinii pneumonia. Most people exposed to P. jiroveci don’t get pneumonia because their immune systems are healthy and strong. People whose immune systems are weak because of HIV infection and other medical conditions can get PCP. PCP is less common than it used to be. It is still the most common serious infection in people who have advanced HIV disease in the United States.
Others who get PCP are usually taking medicines that lower the body’s ability to fight germs or sickness. They may have other medical conditions, such as:
- Blood cancer.
- Inflammatory or autoimmune diseases (for example, lupus or rheumatoid arthritis).
- Organ or stem cell transplant.
Symptoms of PCP
See your doctor right away if you have a weakened immune system and have the following symptoms:
- trouble breathing (especially with exercise)
- chest pain
- fatigue (extreme tiredness).
Most cases are mild. People with severe PCP may die if the infection isn’t treated quickly.
What causes PCP?
Most scientists believe PCP is spread in the air. They don’t know if it lives in the soil or anywhere else. The P. jiroveci fungus is common all over the world. It is not spread through sexual contact. You cannot prevent being exposed to the fungus.
How is PCP diagnosed?
PCP is diagnosed by lab tests of fluid or tissue from your lungs.
Can PCP be prevented or avoided?
If you are at risk of PCP because you have HIV, you may be able to lower your risk for getting PCP. A good medicine for preventing PCP is trimethoprim-sulfamethoxazole, or TMP-SMX. TMP-SMX is a combination of 2 medicines. Ask your doctor if you should be taking this medicine (or another medicine) to prevent illness.
Talk to your doctor about medicines you might be able to take if you have other medical conditions that weaken your immune system.
The pneumonia vaccine does not protect you against PCP. It protects you against a different kind of pneumonia. There is no vaccine for PCP.
If you have HIV, your doctor will test your blood regularly to check how strong your immune system is. Your doctor may prescribe TMP-SMX to prevent PCP. Your doctor may also have you start taking the medicine as a preventive therapy if you get certain symptoms. These symptoms may be a temperature above 100°F that lasts for 2 weeks or longer, or a yeast infection in your mouth or throat (also called “thrush”).
People who have severe cases of PCP are treated in a hospital with IV medicine. The medicine is put into the vein through a tube. As they get better, or if the illness was mild to begin with, medicine can be taken in pill form. If you can’t take TMP-SMX, or don’t get better quickly with it, you can take other medicines or combinations of medicines.
Living with PCP
Recent studies have shown that a strong immune system should protect you from PCP. But if you also have conditions that would make you more likely to get PCP, talk to your doctor about medicines that could lower your risk for getting PCP.
Know that taking TMP-SMX might cause a rash. It might make you feel sick. If you have just a mild reaction, you should keep taking TMP-SMX because it works better than any other medicine to prevent PCP.
If you have already had PCP, you can get it again. Taking TMP-SMX can prevent second infections with PCP.
Questions to ask your doctor
- I have had PCP before. Am I at risk to get it again?
- How will I know if my medicine is working to treat my PCP?
- I can’t take TMP-SMX. What other medicines can I take to treat PCP?
Copyright © American Academy of Family Physicians
This information provides a general overview and may not apply to everyone. Talk to your family doctor to find out if this information applies to you and to get more information on this subject.