Using acid suppressive medications, such as proton pump inhibitors and histamine2 receptor antagonists, may increase the risk of developing pneumonia, states an article in CMAJ.

Acid suppressive drugs are the second leading medication worldwide, totaling over US$26 billion in sales in 2005. Recently, medical literature has looked at unrecognized side effects in popular medications and their impact on public health.

This systematic review, which incorporated all relevant studies on the association of acid suppressive medications and pneumonia that could be identified to August 2009, showed that out of every 200 inpatients being treated with acid suppressive medication one will develop pneumonia.

"Several previous studies have shown that treatment with acid-suppressive drugs might be associated with an increased risk of respiratory tract infections and community-acquired pneumonia in adults and children. However, the association between use of acid-suppressive drugs and risk of pneumonia has been inconsistent, writes Dr. Chun-Sick Eom and Dr. Sang Min Park, Department of Family Medicine, Seoul National University Hospital, Seoul, Korea with coauthors. "Given the widespread use of proton pump inhibitors and histamine2-receptor antagonists, clarifying the potential impact of acid-suppressive therapy on the risk of pneumonia is of great importance to public health."

Since 40-70% of hospitalized patients receive these drugs it may mean that deaths from hospital-acquired pneumonia could be caused by acid suppressive medications. The impact of acid suppressive medication on community-acquired pneumonia could be much greater.

The authors conclude that physicians should use caution when prescribing acid suppressive medication, especially in patients with a high risk of developing pneumonia.