The pneumonia risk is the same whether someone has been taking the drugs for a long time or even as a one-off to treat a specific problem, say researchers from the Group Health Research Institute. Either way, the risk is "significantly high".
The researchers studied a group of 1,000 older patients, aged between 65 and 94 years, who had developed pneumonia, and were compared to 2,000 healthy people. The use of anticholinergic medication was a significant factor among those who had pneumonia.
Anticholinergic properties-which block the acetylcholine neurotransmitter in the brain-are found in many medications, ranging from antihistamines to treat allergies such as hay fever to antidepressants and insomnia remedies.
Older people are often taking more than one anticholinergic at the same time, and the researchers were also concerned about a cumulative effect.
Last month, researchers discovered the drugs also increase the risk of dementia. Common side effects include sedation, confusion, constipation, vision changes, and dry mouth and eyes.
(Source: Journal of the American Geriatrics Society, 2015: doi: 10.1111/jgs.13327)