Pneumonia is inflammation in your lungs caused by an infection.

You have two lungs, one on each side of your chest.

Each lung has separate sections, called lobes.

Normally, as you breathe, air moves freely through your trachea, or windpipe,

then through large tubes, called bronchi,

through smaller tubes, called bronchioles,

and finally into tiny sacs, called alveoli.

Your airways and alveoli are flexible and springy.

When you breathe in, each air sac inflates like a small balloon.

And when you exhale, the sacs deflate.

Small blood vessels, called capillaries, surround your alveoli.

Oxygen from the air you breathe passes into your capillaries,

then carbon dioxide from your body passes out of your capillaries

into your alveoli so that your lungs can get rid of it when you exhale.

If you have pneumonia, your airways or lungs have an infection caused by germs

such as:




or parasites.

Your airways catch most germs

In the mucus that lines your trachea, bronchi, and bronchioles.

Hair-like cilia lining the tubes

constantly push the mucus and germs out of your airways,

where you may expel them by coughing.

Sometimes germs make it past your mucus and cilia,

and enter your alveoli.

Normally, cells of your immune system attack these germs,

which keep them from making you sick.

However, if your immune system is weakened due to

age, illness, or fatigue,

pneumonia-causing germs can

overwhelm your immune cells and begin to multiply.

Your bronchioles and alveoli become inflamed

as your immune system attacks the multiplying germs.

The inflammation causes your alveoli fill with fluid,

making it difficult for your body to get the oxygen it needs.

If you have lobar pneumonia, one lobe of your lungs is affected.

If you have bronchopneumonia, many areas of both lungs are affected.

Pneumonia may cause the following symptoms:

difficulty breathing

chest pain

coughing fever and chills



muscle pain

and fatigue.

Pneumonia can lead to serious complications.

Respiratory failure occurs when your breathing becomes so difficult

that you need a machine called a ventilator to help you breathe.

Bacteremia occurs when the bacteria causing your pneumonia

move into your bloodstream where they may travel to infect

other organs.

In some cases of pneumonia,

a large collection of fluid and pus, called an abscess, may form inside one of your lungs.

If an abscess forms around the outside of your lung, it’s called an empyema.

Possible treatments for pneumonia include

antibiotics, if the cause is bacteria or a parasite

antiviral drugs, if the cause is a flu virus

antifungal medication, if the cause is a fungus

rest and drinking plenty of fluids

and over-the-counter, or OTC remedies,

to manage your fever, aches, and pain.

If you have severe pneumonia you may be admitted to the hospital,

and given intravenous antibiotics and oxygen.