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-associated pneumonia. You can also get it when you are in a hospital or nursing home. This is called healthcare-associated pneumonia. It may be more severe because you already are ill. This topic focuses on pneumonia you get in your daily life.

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.

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.
• Fever.
• Fast breathing and feeling short of breath.
• Shaking and “teeth-chattering” chills.
• Chest pain that often feels worse when you cough or breathe in.
• Fast heartbeat.
• Feeling very tired or very weak.
• Nausea and vomiting.
• Diarrhea.

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.

Your doctor will ask you about your symptoms and do a physical exam. He or she may order a chest X-ray and a complete blood count (CBC). 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 may need.

If pneumonia is caused by bacteria, your doctor will give you antibiotics. These almost always cure pneumonia caused by bacteria. Be sure to take the antibiotics exactly as instructed. Do not stop taking them just because you feel better. You need to take the full course of antibiotics.

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 is not treated with antibiotics. Sometimes, antibiotics may be used to prevent complications. But home treatment, such as rest and taking care of your cough, usually is all that is done.

Experts recommend immunization for children and adults. Children get the pneumococcal vaccine as part of their routine shots. Two different types of pneumococcal vaccines are recommended for people ages 65 and older. If you smoke, or you have a long-term health problem, it’s a good idea to get a pneumococcal vaccine. It may not keep you from getting pneumonia. But if you do get pneumonia, you probably won’t be as sick. You can also get an influenza vaccine to prevent the flu, because sometimes people get pneumonia after having the flu