A major study of GP prescribing has found that, while the vast majority of prescriptions written by family doctors are appropriate and effectively monitored, around one in 20 contain an error.

Researchers looking at a sample of GP practices in England found that where there were errors, most were classed as mild or moderate, but around 1 in every 550 prescription items was judged to contain a serious error. The most common errors were missing information on dosage, prescribing an incorrect dosage, and failing to ensure that patients got necessary monitoring through blood tests.

The research, commissioned by the General Medical Council, is the largest-scale study of its kind. The report recommends a greater role for pharmacists in supporting GPs, better use of computer systems and extra emphasis on prescribing in GP training.

GMC chair Professor Sir Peter Rubin 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...to ensure that our findings are translated into actions that help protect patients."

Professor 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 on-going 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."

A senior medical adviser to the UK-wide medical defence organisation MDDUS is Dr John Holden, an expert in medico-legal issues. Dr Holden commented: "This study underlines the fact that, while prescribing errors are rare, they can have serious consequences for patient care. MDDUS supports the GMC's move to improve prescribing standards and we hope this study will alert doctors to the prescribing pitfalls and encourage them to take extra care.

"MDDUS has dealt with a number of cases where doctors have faced fitness-to-practise proceedings regarding prescribing errors, many of which could have been easily avoided. In one case a doctor prescribed methotrexate daily instead of weekly to an arthritis patient who became seriously unwell and required hospital treatment.

"Other complaints relate to drugs that require close monitoring, such as anti-depressants, being issued as repeat prescriptions without sufficient patient follow-up and monitoring.

"These errors could have been avoided if robust prescribing systems had been in place to monitor patients and ensure dosage information is accurate."