Pneumonia is a lung infection that can make you very sick. You may cough, run a fever, and have a hard time breathing. For most people, pneumonia can be treated at home. It often clears up in 2 to 3 weeks. But older adults, babies, and people with other diseases can become very ill. They may need to be in the hospital.
You can get pneumonia in your daily life, such as at school or work. This is called community-based pneumonia. You can also get it when you are in a hospital or nursing home. This is called hospital-based pneumonia. It may be more severe because you already are ill. This topic focuses on pneumonia you get in your daily life.
What causes pneumonia?
Germs called bacteria or viruses usually cause pneumonia.
Pneumonia usually starts when you breathe the germs into your lungs. You may be more likely to get the disease after having a cold or the flu. These illnesses make it hard for your lungs to fight infection, so it is easier to get pneumonia. Having a long-term, or chronic, disease like asthma, heart disease, cancer, or diabetes also makes you more likely to get pneumonia.
- In most cases, the specific organism (such as bacteria or virus) cannot be identified even with testing. When an organism is identified, it is usually the bacteria Streptococcus pneumoniae.
- Other bacteria that may cause pneumonia include Haemophilus influenzae, Mycoplasma pneumoniae, Chlamydophila pneumoniae, Legionella pneumophila (the bacteria that cause Legionnaires’ disease), Staphylococcus aureus, Moraxella catarrhalis, Streptococcus pyogenes, Neisseria meningitidis, or Klebsiella pneumoniae. Mycoplasma pneumonia is sometimes mild and called walking pneumonia.
- Viruses, such as influenza A (the flu virus) and respiratory syncytial virus (RSV) can cause pneumonia.
In people with 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 frequently causes pneumonia in people who have AIDS. Some doctors may suggest an HIV test if they think that Pneumocystis jiroveci is causing the pneumonia.
You may get pneumonia:
- After you breathe infected air particles into your lungs.
- After you breathe certain bacteria from your nose and throat into your lungs. This generally occurs during sleep.
- During or after a viral upper respiratory infection, such as a cold or influenza (flu).
- As a complication of a viral illness, such as measles or chickenpox.
- If you breathe large amounts of food, gastric juices from the stomach, or vomit into the lungs (aspiration pneumonia). This can happen when you have had a medical condition that affects your ability to swallow, such as a seizure or stroke.
A healthy person’s nose and throat often contain bacteria or viruses that cause pneumonia. Pneumonia can develop when these organisms spread to your lungs while your lungs are more likely to be infected, such as during or soon after a cold or if you have a long-term (chronic) illness, such as chronic obstructive pulmonary disease.
You can get pneumonia in your daily life, such as at school or work (community-based pneumonia) or when you are in a hospital or nursing home (hospital-based pneumonia). Treatment may differ in hospital-based pneumonia because bacteria causing the infection in hospitals may be different from those causing it in the community.
What are the symptoms of pneumonia?
Symptoms of pneumonia caused by bacteria usually come on quickly. They may include:
- Cough. You will likely cough up mucus (sputum) from your lungs. Mucus may be rusty or green or tinged with blood.
- Fast breathing and feeling short of breath.
- Shaking and “teeth-chattering” chills. You may have this only one time or many times.
- Chest pain that often feels worse when you cough or breathe in.
- Fast heartbeat.
- Feeling very tired or feeling very weak.
- Nausea and vomiting.
When you have mild symptoms, your doctor may call this “walking pneumonia.”
Older adults may have different, fewer, or milder symptoms. They may not have a fever. Or they may have a cough but not bring up mucus. The main sign of pneumonia in older adults may be a change in how well they think. Confusion or delirium is common. Or, if they already have a lung disease, that disease may get worse.
Symptoms caused by viruses are the same as those caused by bacteria. But they may come on slowly and often are not as obvious or as bad.
How is pneumonia diagnosed?
Your doctor will ask you about your symptoms and do a physical exam. He or she may order a chest X-ray and a blood test. This is usually enough for your doctor to know if you have pneumonia. You may need more tests if you have bad symptoms, are an older adult, or have other health problems. In general, the sicker you are, the more tests you will have.
Your doctor may also test mucus from your lungs to find out what germ is causing your pneumonia. Finding the exact germ can help your doctor choose the best medicine for you.
How is pneumonia treated?
Your doctor will give you medicines called antibiotics. These almost always cure pneumonia caused by bacteria. You need to take all of your antibiotics so you get well. Do not stop taking them because you feel better. Take them exactly as your doctor tells you.
Pneumonia can make you feel very sick. But after you take antibiotics, you should start to feel much better. Call your doctor if you do not start to feel better after 2 to 3 days of antibiotics. Call your doctor right away if you feel worse.
There are things you can do to feel better during your treatment. Get plenty of rest and sleep, and drink lots of liquids. Do not smoke. If your cough keeps you awake at night, talk to your doctor about using cough medicine.
You may need to go to the hospital if you have bad symptoms, a weak immune system, or another serious illness.
Pneumonia caused by a virus usually cannot be treated with antibiotics. Home treatment, such as rest and taking care of your cough, is the only treatment.
How can you prevent pneumonia?
If you are older than 65 or you have a heart or lung problem, you may want to get a pneumonia vaccine. It may not keep you from getting pneumonia. But if you do get pneumonia, you probably will not be as sick.
You can also lower your chances of getting pneumonia by staying away from people who have the flu, colds, measles, or chickenpox. You may get pneumonia after you have one of these illnesses.