Audit Scotland said though progress had been made in the past seven years, greater efficiency would provide the NHS with a valuable cash injection.
Its report highlighted the waste of unnecessary repeat prescriptions issued by GPs, over-ordering and giving patients multiple drugs they did not need. But it praised GPs for cutting their prescription spend despite a rise of almost a third on the number given out since 2004.
Auditor General for Scotland Caroline Gardner said: “The volume of drugs prescribed has continued to rise but the NHS has significantly improved how it manages spending.
“Demand for prescriptions is likely to increase further and it’s important the NHS continues to work with GPs to make sure patients get the drugs they need and spending is well managed.”
The report revealed prescribing costs Scotland’s NHS around £1 billion a year and that, on average, a GP practice in Scotland hands out 70 prescriptions a day.
It also highlighted how a quarter of people in Scotland were now prescribed four or more different drugs and that heart conditions, diabetes and respiratory illnesses were among the most common conditions treated with drugs.
The biggest factors affecting prescribing were patient age and levels of deprivation. More than 900,000 people in Scotland over the age of 50 are taking four or more different drugs while GP practices serving the most deprived areas prescribe on average 46 per cent more drugs per head of population than those in the least deprived areas.
The report urges Scotland’s health boards to target areas for further savings without affecting the level of care patients received. These include turning to generic drugs and reviewing the needs of patients receiving many different medicines.
The Prescribing in General Practice in Scotland report said while it was too early to judge the impact of prescriptions charges being scrapped in 2011, there was a risk more people were seeking prescriptions and this could cost the public purse more than the £57m the SNP estimated for 2011-12.
In 2011/12 there were 91 million prescriptions issued by around 1,000 GP practices in Scotland, costing £974m, the report said.
Scottish Conservative spokesman Jackson Carlaw said: “We already know there has been an increase in frivolous prescriptions as a result of them being made free. This money could be better spent elsewhere.”