Respiratory conditions like bronchitis and pneumonia symptoms are often hard to differentiate, but this guide can help.

Bronchitis and pneumonia both affect the lungs and share some common symptoms, but they are different diseases that require different treatment. Here's how you can tell the difference.

Bronchitis

The less severe of the two, acute bronchitis is caused by inflammation of the bronchi, the branching tubes that deliver air into the lungs. (Chronic bronchitis is a different subject altogether.)

The most common symptoms of bronchitis include:

• Coughing with clear, yellow or green sputum (the gunk you cough up)
• Fatigue
• Wheezing
• Runny, stuffy nose occurring before chest congestion begins
• Shortness of breath, usually following a coughing jag
• Discomfort in the center of the chest due to cough
• Mild fever

Although yellow or green sputum is often thought to indicate bacterial infection, don't be fooled.

"Over 80 to 90 percent of bronchitis in otherwise healthy people is viral, not bacterial, in origin, especially if the symptoms of bronchitis follow a cold," says Homer Boushey, M.D., a lung specialist and professor emeritus of medicine at the University of California, San Francisco.

Viral infections cannot be treated with antibiotics. In fact, says Boushey, antibiotics will kill many of the healthy, protective bacteria in your body. "That leaves you more susceptible to disease-causing bacteria."

Acute bronchitis will most often go away on its own within a week to 10 days, though your mucus-y cough will likely persist for several more weeks.

"It's just a matter of the body cleaning up the mess," says pulmonologist Len Horovitz, M.D., of Lenox Hill Hospital in New York. "Most people recover just fine from bronchitis."

Pneumonia

An inflammation of the lungs, pneumonia has many of the same symptoms as bronchitis, including:

• Persistent fever (often high)
• Cough, often with yellow or green mucus
• Chills, which sometimes cause shaking
• Shortness of breath
• Sharp chest pain
• Confusion (which occurs primarily in older people)

Though many of the signs may be similar, pneumonia is much more serious than acute bronchitis. It's more often caused by bacteria than by a virus, which means that antibiotics can be used to treat it. However, bacterial pneumonia can be a fast-moving disease that needs attention right away, says Boushey.

"Don't wait too long to get treated," he warns. "If you come in with very advanced pneumonia, it may be too late. For people who come in right away, we have good treatments."

When to see a doctor

Older people do worse with respiratory infections (whether viral or bacterial), especially if they have other health problems such as chronic obstructive pulmonary disease, heart disease, diabetes, kidney disease or cancer. If you have symptoms, play it safe and see your doctor.

"Any time you have a fever or a cough, you should go in," says Horovitz. "Any time you feel bad, you should go in, because you never know what you are dealing with. Don't wait until you are in extremis."

Your doctor will listen to your lungs and, if necessary, take an X-ray of your chest, which will identify pneumonia infection.

Prevention

To protect yourself against bacterial pneumonia, there are two pneumonia vaccines recommended if you're 65 or older. If you have underlying health problems, like COPD or diabetes, or if you smoke, you will likely need one at an earlier age. Talk to your doctor.

You can reduce your chances of getting acute bronchitis by practicing good hygiene.

"That means handwashing, especially around kids with colds," says Boushey. "We love our grandchildren, but they do spread viruses. Get them to wash their hands frequently and to sneeze and cough into their elbows, not their hands. Those simple measures are important."

Horovitz recommends washing your hands before you touch your face. "You introduce infection-causing germs through your nose, your mouth, your eyes. You can touch sewers all day long and not get sick, as long as you don't touch your face before you wash your hands."

Finally, if you have gastroesophageal reflux disease (GERD), get it treated, says Boushey. "The acid [produced by GERD] irritates the airways in the lungs, which makes them more susceptible to viruses and bacteria."