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In only a minority of cases, national guidelines on tablet strength designed to avoid accidental methotrexate overdose are breached.

High doses of methotrexate increase the risk of toxicity and 21 deaths have been attributed to methotrexate (1993-2017). 

Doctors are advised to prescribe only 2.5mg tablets, and avoid 10mg tablets, to minimise the risk of accidental overdose.

This group of researchers from Oxford analysed data from 7349 practices in England and found that 1689 (23%) prescribed both 2.5mg and 10mg tablets to the same patient.

However the prescribing of 10mg tablets has fallen over the preceding seven years,with 10mg tablets as a proportion of all methotrexate falling from 9.1% to 3.4%.

Dr Ben Goldacre, Director of the DataLab in the Nuffield Department of Primary Care Health Sciences at the University of Oxford, NHS doctor, and co-lead on the study, says:

‘Unsafe methotrexate prescribing remains common, with substantial variation between GP practices. We recognise that clinicians are often overwhelmed with guidance. We have therefore produced a free, publicly funded, openly accessible audit tool at This allows any clinician to easily review their own practice’s compliance. Our data updates every month So clinicians can track improvements over time.’

Read more

Trends and variation in unsafe prescribing of methotrexate: a cohort study in English NHS primary care
Brian MacKenna, Helen J Curtis, Alex J Walker, Richard Croker, Seb Bacon, Ben Goldacre.


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