Strict guidelines for treating paracetamol overdoses - introduced 18 months ago - are costing the NHS millions of pounds a year, researchers claim.
The number of patients receiving hospital treatment for paracetamol poisoning in the UK each year has risen by almost 50 per cent since the guidelines were updated by the Medicines and Health Regulatory Authority, a study estimates.
Researchers have assessed the impact of the MHRA decision to revise the guidelines, which was taken following the death of a young girl from a paracetamol overdose.
Patients with a life-threatening level of paracetamol in their blood are treated with the common antidote - acetylcysteine - given by intravenous drip. By lowering the treatment threshold to include patients with relatively low paracetamol levels, the MHRA predicted it would save one additional life around every two years.
According to the study, more than 31,000 extra patients would need to be treated to achieve this target at an approximate cost of £17.4 million to the NHS.
The researchers say that treatment could also be placing patients at unnecessary risk of unwanted side effects from the antidote, such as severe allergic reactions.
The team, led by the University of Edinburgh, estimated the impact of the revised guidelines by looking at the numbers of patients treated for paracetamol poisoning at large hospitals in Edinburgh, London and Newcastle upon Tyne.
By applying their findings to the rest of the UK, they estimated that the number of patients receiving hospital treatment for paracetamol poisoning increased from around 33,000 to 49,000 a year after the changes were introduced.
The study is published in the British Journal of Clinical Pharmacology.
Paracetamol is the most common cause of overdose in the UK but deaths are rare - between 150 and 250 people a year. Some people overdose mistakenly owing to confusion over which over the counter medicines contain paracetamol.
Professor Nick Bateman, of the University of Edinburgh's British Heart Foundation Centre for Cardiovascular Science, said: "Changes to the treatment guidelines for paracetamol overdoses are increasing the pressure on hard-pressed emergency departments and hospitals. A full review of present UK approaches to managing this common poisoning is required."