Codeine and Breastfeeding: In 2026, a challenge to the landmark 2006 publication that advised against its use

Fraudulent publications leading to a breastfeeding ban, retraction of the pivotal study underway…

A fascinating investigation into codeine and breastfeeding published in the New Yorker — presented here!

For nearly two decades, codeine was contraindicated by the FDA for breastfeeding women, following a 2006 case report published in The Lancet describing the death of an infant. This case, attributed to ultra-rapid metabolism of codeine into morphine in the mother (hyper-metabolism via CYP2D6), shaped global recommendations.

However, an investigation published in 2026 calls this case into question : it may in fact be a case of poisoning, presented with falsified toxicological results. The New Yorker details the twists and turns surrounding the publication of this case.

In April 2005, infant Tariq Jamieson died from opioid poisoning while his mother, Rani, was taking codeine (Tylenol No. 3) for postpartum pain (the "Toronto Case"). Dr. Gideon Koren, a renowned expert pharmacologist, published a study in The Lancet in 2006 concluding that this was a unique case of death through transmission via breast milk, due to the mother's ultra-rapid metabolism — which led to a worldwide ban on codeine for breastfeeding women.

However, the investigation, drawing on explanations from toxicologist David Juurlink, reveals major flaws. These were raised repeatedly over the years by other toxicologists, but without any correction to the publication.

The morphine and acetaminophen levels found in Tariq's blood are biologically impossible to achieve through breast milk alone, and the presence of unmetabolized codeine in the baby's stomach suggests direct administration. The presence of codeine was never mentioned in the 2006 study: critical toxicological data had been concealed.

The investigation also demonstrates that Koren published a second fictitious case ("Baby Boy Blue") to support his theory; this publication was retracted by the Canadian journal that had published it.

The toxicology laboratory he directed was shut down due to errors in drug analyses of mothers' hair samples. These analyses, used in court proceedings, led to children being placed in foster care.

In light of this data and the retraction by two Canadian journals, The Lancet has issued an "expression of concern" regarding the original publication. The clinical recommendations that led many mothers to avoid breastfeeding, or to receive insufficiently effective medications (and to suffer), or more potent opioids, should therefore be reviewed.

Hale's online resource "Medications and Mothers' Milk" notes that cases of adverse effects through breast milk exposure have been reported with the use of codeine in breastfeeding mothers. These include bradycardia, apnea, and cyanosis. Most cases occur in the first week of life, when the infant's elimination mechanisms (renal and hepatic) are immature.

It cites a cohort study of 85,000 breastfeeding dyads in Ontario, which found no association between opioid prescriptions in the mother (including codeine) and deaths or serious adverse effects in the infant.

In conclusion

In breastfeeding mothers, non-opioid analgesics (paracetamol, ibuprofen) are recommended as first-line treatment.

Codeine is probably not as dangerous as has been suggested over the past 20 years, as recommendations were based on a single case report whose scientific integrity is now in question.

Its use at low doses and for a short duration is possible (though Hale notes it is certainly not an opioid of choice, as 10% of people metabolize it slowly and the analgesic effect will be insufficient).

The primary area of clinical vigilance remains the mother's condition: maternal drowsiness is correlated with the risk of adverse effects in the infant.

Bibliography

Springer Publishing. Codeine and Breastfeeding: What Women's Health Clinicians Need to Know Now

The New Yorker. (2026). Did a Celebrated Researcher Obscure a Baby's Poisoning?

Retraction Watch. (2026). Lancet flags long-scrutinized report of infant poisoned by opioids in breast milk.

The Lancet. (2026). Expression of Concern: Pharmacogenetics of morphine poisoning in a breastfed neonate of a codeine-prescribed mother.

Halesmed.com. Medications and Mothers' Milk. Codeine monograph.

Breastfeeding and codeine guidance in doubt after calls for retraction of pivotal Lancet study. BMJ 2026;392:s498 http://doi.org/10.1136/bmj.s498