Breastfeeding and codeine guidance in doubt after calls for retraction of pivotal Lancet study

A pivotal Lancet case report suggesting that codeine given to breastfeeding mothers could trigger opioid overdoses in babies is facing demands for investigation.The 2006 report came under scrutiny after a member of the original research team wrote to the journal on 20 January 2026 alleging misconduct by the team’s leader.The Lancet has now issued an expression of concern over the paper1 and requested an investigation by Toronto’s Hospital for Sick Children, widely known as SickKids, where the paper was written under the leadership of the pharmacologist Gideon Koren.Koren’s work has come under intense focus in recent weeks after it emerged that a separate case report describing an overdose in another baby that appeared to support the Lancet paper’s hypothesis was entirely fictitious.2 That report was written by Koren in Paediatrics & Child Health, the journal of the Canadian Paediatric Society, but no mention was made of its fictitious nature and...