PNEUMONIA, AN INFECTION that inflames the air sacs of one or both lungs, affects millions of Americans each year. The air sacs, or alveoli, are where the oxygenation of the blood occurs. The alveoli may fill with fluid or pus, causing a cough with phlegm or pus. Pneumonia can range from mild to life-threatening and is most serious in infants, young children, people older than 65 and people with health problems or weakened immune systems.

Bacteria, viruses and fungi can cause pneumonia. In adults, bacteria are the most common cause. Bacteria and viruses living in your nose, sinuses or mouth may spread to your lungs. You may breathe some of these germs directly into your lungs, or you may inhale food, vomit or fluids from the mouth into your lungs (aspiration pneumonia).

The most common type of pneumonia-causing bacteria is Streptococcus pneumoniae (pneumococcus). Walking pneumonia, often called atypical pneumonia, is caused by other bacteria. The fungus Pneumocystis jiroveci can cause pneumonia in people whose immune systems are not working well, such as those with advanced HIV infection. Viruses such as the flu are also a common cause of pneumonia.

Risk factors that increase your chances of getting pneumonia include chronic obstructive pulmonary disease; bronchiectasis; cystic fibrosis; dementia; stroke; brain injury; cerebral palsy or other brain disorders; and immune system problems due to cancer treatment, HIV/AIDS, organ transplant or other diseases. Other risk factors include serious illnesses such as heart disease, liver cirrhosis or diabetes mellitus; recent surgery or trauma; or surgery to treat cancer of the mouth, throat or neck. Smoking cigarettes, excessive use of alcohol or being undernourished also increases your risk of pneumonia.

The most common symptoms of pneumonia are cough (you may cough up greenish or yellow mucus or bloody mucus), mild or high fever, shaking chills and shortness of breath. The shortness of breath may only occur when you climb stairs or exert yourself. Other symptoms include confusion, especially in older people; excess sweating and clammy skin; headache; loss of appetite; low energy and fatigue; not feeling well; or sharp or stabbing chest pain that gets worse when you breathe deeply or cough.

See your health care provider as soon as possible. Your provider will examine your lungs with a stethoscope, listening for decreased breath sounds and crackles in your lungs. A pulse oximetry will check your oxygen saturation on room air. You may have a chest X-ray, blood work such as a complete blood count and arterial blood gases, blood and sputum cultures to look for the organism causing the infection, a CT scan or a bronchoscopy to examine your lungs and take sputum samples.

If the assessment points to early pneumonia, you will likely be told to force fluids and be placed on a broad-spectrum antibiotic, Mucinex or its generic form (600 mg two to three times a day) to assist in coughing up secretions, and mini nebulizer treatments every eight hours while at home.

If your pneumonia has progressed, you may be hospitalized to be monitored closely. You may be placed on IV antibiotics, oxygen and breathing mini nebulizer treatments plus an incentive spirometer to help open your airways. If you are diagnosed with viral pneumonia, you may receive other medications, such as an antiviral if the cause is the flu. Antibiotics do not kill viruses. Get plenty of sleep. If you cannot sleep at night, take naps during the day. With treatment, most people improve in two weeks; recovery may take six weeks. Adults older than 65 or very sick individuals may take longer to recover.

Possible complications of pneumonia include the need for a mechanical ventilator; bacteremia, in which the infection spreads into the blood; septic shock, an overwhelming infection attacking the body; lung abscess; other pulmonary problems such as respiratory failure, pleurisy or pleural effusion, in which fluid collects in the lungs; and kidney failure.

You can prevent pneumonia by washing your hands or using alcohol-based sanitizers often, especially before preparing or eating food and after blowing your nose, going to the bathroom, changing a baby’s or adult’s diaper or coming in contact with people who are sick. Do not smoke. Tobacco damages your lungs’ ability to fight infections.

Vaccines may prevent some types of pneumonia. The flu vaccine can help prevent pneumonia caused by the flu virus. The pneumococcal vaccine lowers your chances of getting pneumonia from Streptococcus pneumoniae and helps protect against some of the 90-plus types of pneumococcal bacteria. Vaccines are even more important for older adults and people with diabetes, asthma, emphysema, HIV, cancer, organ transplants and other chronic diseases and conditions.

Get your children vaccinated with the child strength of pneumococcal, flu, pertussis and Hib vaccines. Haemophilus influenzae type b (Hib) is a bacterium that can cause pneumonia and meningitis. The vaccine is recommended in the United States for all children younger than 5 years of age. It is often given to infants starting at 2 months old.

When infants are too young to be immunized, parents, family members, relatives and caregivers should be vaccinated. Keep yourself healthy: Limit your intake of alcohol, keep your immune system strong, get enough sleep, exercise regularly and eat a healthy diet.

The content of this article is for informational purposes only. It is not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your physician or other qualified health care provider with any questions you may have regarding a medical condition.