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, small babies, and people with other diseases can become very ill. You can get pneumonia in your daily life, such as at school or work.
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, or heart disease makes you more likely to get pneumonia.