Skip to content

Lung Disease & Respiratory Health Center

Font Size

Pneumonia - What Happens

After you've been infected with a pneumonia-causing organism, it takes as little as 1 to 3 days or as long as 7 to 10 days for symptoms to appear. How severe pneumonia is and how long it lasts depend on:

  • Your age and health. Older, sicker people usually have more severe cases. And their cases of pneumonia are more likely to cause complications, such as bacteria in the bloodstream (bacteremia) or throughout the body (septicemia).
  • Whether bacteria or a virus caused the pneumonia. Viral pneumonia usually is less severe than bacterial pneumonia.
  • How quickly you treat it. The sooner you treat pneumonia, the sooner symptoms go away.
  • Your immune system. People who have impaired immune systems are more likely to have more severe pneumonia than people who have healthy immune systems.

In healthy people, pneumonia can be a mild illness that is hardly noticed and clears up in 2 to 3 weeks. In older adults and in people with other health problems, recovery may take 6 to 8 weeks or longer.

Recommended Related to Lung Disease/Respiratory Problems

Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) causes scar tissue to grow inside your lungs. Usually, when you breathe in, oxygen moves through tiny air sacs into your bloodstream. From there, it travels to organs in your body. IPF scar tissue is thick, like the scars you get on your skin after a cut. It slows oxygen flow from your lungs to your blood, which can keep your body from working as it should. Low oxygen levels and the stiff scar tissue make it hard to breathe. There’s no cure for IPF. The illness...

Read the Idiopathic Pulmonary Fibrosis article > >

Going to the hospital

If you have severe pneumonia, you may have to go to the hospital:

  • In most cases of pneumonia you get in your daily life, such as at school or work (community-based pneumonia), it is not necessary to go to the hospital.1
  • About one-third of people with community-based pneumonia are age 65 or older.1 Older adults are treated in the hospital more often and stay longer for the condition than younger people.1 Pneumonia is more serious in this group, because they often have and may develop other medical problems.

Spreading pneumonia to others

If your pneumonia is caused by a virus or bacteria, you may spread the infection to other people while you are contagious. How long you are contagious depends on what is causing the pneumonia and whether you get treatment. You may be contagious for several days to a week.

If you get antibiotics, you usually cannot spread the infection to others after a day of treatment.

    WebMD Medical Reference from Healthwise

    Last Updated: September 09, 2014
    This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.
    Next Article:

    Today on WebMD

    man coughing
    You may not even know you have it.
    blood clot
    Signs of this potentially fatal complication.
    man coughing
    When a cold becomes bronchitis.
    human lungs
    Causes behind painful breathing, fluid buildup.

    chest x-ray
    Bronchitis Overview
    Copd Myth Fact Quiz
    Energy Boosting Foods

    woman coughing
    Lung xray and caduceus