HealthJuly 09, 2015

Common class of hazardous drugs may be linked to pneumonia risk

Anticholinergics have been shown to increase the risk of dementia in older adults. They may also increase the risk of pneumonia, according to new research published in the Journal of the American Geriatrics Society.

The broad class of drugs includes medications used to treat a wide range of conditions, such as allergies (diphenhydramine, chlorpheniramine), depression (doxepin), insomnia (benzodiazepines) and urinary incontinence (oxybutynin).

The study compared 1,000 patients aged 65 to 94 who developed pneumonia and 2,000 age, sex and year-matched controls who did not develop lung disease.1

"We found a link between both acute and chronic use of anticholinergic medications and a much higher risk for developing pneumonia," said lead author Kathleen J. Paul, MD, MPH.2

The researchers defined "acute use" as having filled a prescription for an anticholinergic within the 90 days prior to a diagnosis of pneumonia. Chronic use entailed filling three or more prescriptions in the year before the diagnosis. The control group had filled no prescriptions for the class of drugs within the previous year.

Among the patients who had pneumonia, 59% had used anticholinergics within the 90 days preceding their diagnosis, and 53% were chronic users of the medications. Among the controls, 35% met the acute use criteria and 36% met the chronic use definition.

Pharmacy records included information about many members' use of over-the-counter medications as well as their prescription fills, enabling the researchers to see a fuller range of the drugs patients had taken. This insight allowed them to detect the association of common anticholinergics such as diphenhydramine (Benadryl), which does not require a prescription, and pneumonia in community-based adult settings.

While the study did not identify how this class of drugs increased pneumonia risk, Paul hypothesized that "one possibility is that by causing sedation and altered mental status, they raise the risk for breathing problems and lung infections."

In light of how frequently older adults experience conditions commonly treated by anticholinergics and the devastating impact of pneumonia on this population, Paul suggested that healthcare providers first suggest other alternatives for treatment, including:

  • Insomnia: First, improve sleep hygiene and implement behavioral changes (such as increased exercise and reduced caffeine) and then try melatonin instead of benzodiazepines or antihistamines.
  • Depression: Counseling has been shown to be as effective as medication in treating depression. Lifestyle changes, such as increased social interaction, more exercise and getting outdoors can also help. For those who need medication, Paul suggested starting with a selective serotonin reuptake inhibitor.
  • Allergies: A second-generation antihistamine such as loratadine does not sedate most people as much as diphenhydramine or chlorpheniramine.
  • Urinary incontinence: Providers may recommend behavioral strategies such as setting an alarm to remind those with this particular condition to attempt to urinate every hour or two.


1. Paul KJ, Walker RL, Dublin S. Anticholinergic medications and risk of community-acquired pneumonia in elderly adults: a population-based case-control study. J Am Geriatr Soc. 2015 Mar;63(3):476-85.

2. Anticholinergic drugs linked to risk for pneumonia in elderly: Group Health study suggests higher risk with acute or chronic use. Group Health Research Institute. March 2, 2015.

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