People who take commonly prescribed sedatives may be at an increased risk of developing and dying from pneumonia, the results of a new study suggest.

Benzodiazepines, also known as sedatives or tranquillisers, are a group of medications that help to regulate sleep, ease agitation and reduce anxiety. They include diazepam (Valium).

According to UK scientists, these drugs have previously been linked to an increased risk of infections and death from sepsis (blood poisoning) in seriously ill patients. They set out to investigate whether a similar link with pneumonia existed.

They looked at almost 5,000 patients who had first been diagnosed with pneumonia between 2001 and 2002. Each was compared with six patients, adding up to almost 30,000 people - these acted as the control group. The use of benzodiazepines was analysed in both groups.

The study showed that people who used the drugs had a 54% increased risk of contracting pneumonia.

Furthermore, users who contracted pneumonia had a 22% increased risk of dying within 30 days. They also had a 32% increased risk of dying within three years of the diagnosis.

The scientists from University College London said the results do not ‘definitively prove cause and effect', but they called for more research into this area.

"Benzodiazepines are commonly prescribed medications that have significant immune effects. Given the widespread use of these drugs, further studies are required to evaluate their safety in the context of infection," they concluded.

Details of these findings are published in the journal, Thorax.