Drug errors cause harm and deaths.

Drug errors in England cause appalling levels of harm and deaths, the then health secretary, Jeremy Hunt warned as research suggested that mistakes are common.

GPs, pharmacists, hospitals and care homes may be responsible for 237 million errors a year, the equivalent of one for every five drugs prescribed.

The study by UK university researchers said most errors caused no problems but more than a quarter could be a factor in thousands of deaths each year.

Among the identified mistakes are the wrong medications being given, incorrect doses dispensed and delays in medication being administered.

The researchers, from Manchester, Sheffield and York universities, acknowledge a lack of available data and the figures are best estimates based on previous research, some of it years old.

They estimate that drug errors cause 700 deaths a year and could also be a factor in between 1,700 and 22,300 others. A total of 1.15 billion drug prescriptions are made each year.

A fifth of the errors related to hospital care, including doctors administering anaesthetic before surgery. The remainder were divided between drugs given in the community by GPs and pharmacists, and those dispensed in care homes.

Royal College of Nursing chief executive, Janet Davies, said the study was deeply concerning.

She added: "There are real problems in preserving patient safety when you haven't got enough staff and there are financial pressures."

She said human error was one of the biggest risks and that overstretched nursing staff and agency workers added to this.

Mr Hunt, who has since become foreign secretary, said he was concerned by the findings, which are global and not confined to the NHS.

He said: "It is a far bigger problem than generally recognised, causing appalling levels of totally preventable harm and death."

He outlined steps the NHS was taking to reduce mistakes, including the adoption of much-delayed electronic prescribing as only a third of hospitals had an effective system in place. The Department of Health and Social Care believes this could cut errors by half.

Chair of the Royal College of General Practitioners, Prof Helen Stokes-Lampard,  said doctors worked hard to avoid making mistakes but were only human. The intense pressures GPs worked under would also be contributing to the problem.