Around one in 20 prescriptions written by family doctors contains an error, according to a newly published study.

Most mistakes were classed as mild or moderate, but around one in every 550 items was judged to contain a serious error, the research commissioned by the General Medical Council found.

The most common of the prescribing or monitoring errors were lack of information on dosage, prescribing an incorrect dosage, and failing to ensure that patients were properly checked with blood tests.

One in eight of all patients had a prescription item with an error - this rose to four in 10 patients aged 75 years and older.

A number of factors were found to be associated with increased risk of prescribing or monitoring errors and these included the number of medicines a patient was taking (there was a 16 per cent increased risk of error for each additional medicine) and the age of the patient (children and those aged 75 years and older were almost twice as likely to have an error as those aged 15-64).

Researchers concluded that causes included deficiencies in the training of GPs regarding safe prescribing, time pressure, and lack of robust systems for ensuring that patients receive necessary blood tests.

Despite these concerns, they found that GPs took prescribing very seriously and used a range of strategies to try to avoid serious errors.

The researchers recommended a greater role for pharmacists in supporting GPs, better use of computer systems and extra emphasis on prescribing in GP training.

Sir Peter Rubin, chairman of the GMC, said: “GPs are typically very busy, so we have to ensure they can give prescribing the priority it needs.

“Using effective computer systems to ensure potential errors are flagged and patients are monitored correctly is a very important way to minimise errors.

“Doctors and patients could also benefit from greater involvement from pharmacists in supporting prescribing and monitoring.

“We will be leading discussions with relevant organisations, including the Royal College of General Practitioners and the Care Quality Commission, and the chief pharmacist in the Department of Health, to ensure that our findings are translated into actions that help protect patients.”

Tony Avery of the University of Nottingham’s medical school, who led the research, said: “Few prescriptions were associated with significant risks to patients but it’s important that we do everything we can to avoid all errors.

“GPs must ensure they have ongoing training in prescribing, and practices should ensure they have safe and effective systems in place for repeat prescribing and monitoring.

“I’d also encourage doctors to share their experiences of prescribing issues both informally within their practices, and also formally where appropriate through local or national reporting systems. Prescribing is a skill, and it is one that all doctors should take time to develop and keep up-to-date.”

The study took place in 15 general practices from three areas of England, regarded as reasonably representative of other general practices in England.

A total of 1,777 patients were included in the study. Their medical records were investigated to identify potential prescribing or monitoring errors associated with 6,048 prescription items issued in the previous 12 months.

The potential errors were considered by researchers to decide whether or not they were errors.