There are more than 230 million errors in administering medication in the NHS each year, new figures show.
The research, commissioned by the Department of Health and Social Care, also shows medication errors may be responsible for around 1,700 deaths a year.
It's a problem which costs the NHS an estimated £1.6bn.
Despite the high numbers, those behind the study say the vast majority of errors do not affect the patient and are spotted beforehand.
Rachel Elliott, Professor of Health Economics from The University of Manchester, is one of the study's authors.
She said: "In a perfect system there would be no errors. But there are no systems, particularly those involving humans, where there are no errors.
"As far as we're concerned this information is actually very useful. I would say people shouldn't be worried, most prescribers, and pharmacists and nurses are aware of the risks associated with medicines and are very vigilant at all stages.
"Unfortunately, systems are not perfect and therefore errors do occur. Most of the errors we've picked up in this 237 million are not going to affect the patient – are not going to even reach the patient."
The Health Secretary Jeremy Hunt will today announce plans to reduce patient harm and improve safety relating to medication errors.
In a speech at the Global Patient Safety summit in London, Mr Hunt will say: "My mission has always been to make the NHS one of the safest healthcare systems and although we do well in international comparisons this new study shows medication error in the NHS and globally is a far bigger problem than generally recognised, causing appalling levels of harm and death that are totally preventable.
"We are taking a number of steps today, but part of the change needs also to be cultural: moving from a blame culture to a learning culture so doctors and nurses are supported to be open about mistakes rather than cover them up for fear of losing their job."
The Government's plans include accelerating the introduction of electronic-prescribing systems across the NHS – essentially robots replacing humans when selecting medication – to cut down on errors.
New systems will also be introduced linking prescribing data in primary care to hospital admissions to allow the NHS to see if a prescription was the likely cause of a patient being admitted to hospital.
There will also be new defences for pharmacists if they make accidental mistakes when administering medication, rather than being prosecuted, to ensure the NHS can learn from errors.
Andrew Iddles' mother Mabel was rushed to hospital in 2014 at the age of 102 after falling at home.
During her time in hospital she was mistakenly given medication meant for a patient in the bed next door – including an insulin injection.
Mr Iddles said, fortunately, the nurse responsible raised the issue quickly.
He said: "It is not easy to detect and, if a patient is not diabetic, a hefty dose of insulin could lower the blood sugar to a fatal level… thus it was very important that the nurse had the courage to admit her mistake straight away so no harm came to my mother."
Many aren't so lucky – with the report finding medication errors may contribute to up to 22,000 deaths a year.
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The British Medical Association has welcomed the plans outlined by the Government, but says more help for GP practices is also needed.
A BMA spokesperson said: "GP practices are facing increasing demand on their services, with patients presenting with increasingly complex health problems, so the Government needs to continue to work with us to establish a workforce strategy including enabling practices to expand their multi-disciplinary team to help meet patients' needs."