More than 200 of the most commonly prescribed drugs—ranging from heart medications, painkillers, and indigestion pills—are linked to depression and suicidal ideation (thoughts) as side effects.

This means that one in three people are unwittingly taking a prescription drug that can cause these mental health problems, say researchers from the University of Illinois.

The risk could be greater still as many older people are taking more than one of the drugs at the same time. Depression has affected around 15 per cent of people who were taking three or more of the drugs, 9 per cent of those taking two drugs, and 7 per cent of those taking just one of the drugs.