A risk factor is something that increases your chance of getting a disease or condition.

It is possible to develop pneumonia with or without the risk factors listed below. However, the more risk factors you have, the greater your chance of developing pneumonia. If you have a number of risk factors, ask your doctor what you can do to reduce your risk.

Smoking and Second-hand Smoke

People who smoke have a much higher risk of developing pneumonia. If you stop smoking, your risk will gradually return to normal. However, this may take as long as 10 years.

You are also at risk for pneumonia if you are regularly exposed to second-hand smoke. For example, children in households where the parents smoke have higher rates of pneumonia than do children in smoke-free households.

Alcohol and Drug Abuse

Alcohol and drug abuse put you at a higher risk of pneumonia. IV drug use can increase your risk of pneumonia and other infectious diseases.

Crowded Living Conditions

The risk of pneumonia is increased among people living in crowded conditions, such as:

• Students in dormitories
• People living in institutions
• Military personnel in barracks
• People living in nursing homes

Medical Conditions

People who are hospitalized have a much higher risk of developing pneumonia than do non-hospitalized individuals. This risk is even higher for people who have recently undergone major surgery or who are on ventilators. Other medical conditions that can increase your risk of developing pneumonia include:

• Conditions that interfere with your gag reflex:
  • Stroke
  • Multiple sclerosis
  • Amyotrophic lateral sclerosis (ALS)
  • Head injury
  • Senile dementia, Alzheimer’s disease
• Conditions that weaken your immune system:
  • AIDS
  • History of organ transplant
  • Cancer (especially leukemia and Hodgkin lymphoma)
  • Chemotherapy drugs
  • Immunosuppressant drugs (including steroids)
• Chronic obstructive pulmonary disease (COPD)
• Diabetes
• Kidney disease
• Sleep apnea
• Heart failure
• Poor nutrition
• Generally debilitated state
• Allergies or asthma
• Liver disease
• Mechanical ventilation

Children have a higher risk of developing pneumonia if they have:

• A weakened immune system
• Gastroesophageal reflux disorder (GERD)
• Lung or heart defects
• Allergies or asthma
• Nervous system defects that affect the muscles of the mouth and/or throat

Age

Pneumonia is more common among certain age groups:

• Infants
• Young children
• Older adults

Genetic Factors

A number of genetic disorders can predispose you to pneumonia, such as:

• Sickle cell disease
• Cystic fibrosis

Environmental Factors

Occupational exposure to toxic chemical fumes and/or smoke can weaken your lung’s defenses. This can increase your vulnerability to pneumonia germs.