A nursing mother who takes codeine could be placing her infant at raised risk of morphine overdose if she is an ultra-rapid metabolizer of codeine, warns the US Food and Drugs Administration (FDA). The FDA says it has examined all available data since The Lancet reported that a 13-day old breastfed baby died from morphine overdose. Levels of morphine in the breast milk had been abnormally high after the mother took small doses of codeine. The codeine had been taken to treat episiotomy pain. Tests revealed the mother was an ultra-rapid codeine metabolizer.
Sandra Kweder, M.D., Deputy Director, Office of New Drugs in FDA’s Center for Drug Evaluation and Research, said “Our best advice to physicians prescribing codeine-containing products to nursing mothers is to prescribe the lowest dose needed for the shortest amount of time. And nursing mothers should always consult their physicians before taking any codeine containing products.”
Codeine can be found in pain relief medicines and drugs to treat cough – it exists in both prescription and OTC drugs. After it is consumed some of it is metabolized to morphine. Depending on their genetic makeup, some people metabolize codeine to morphine at a much faster rate, they are known as ultra-rapid metabolizers. After taking codeine, these people often have much higher-than-normal levels of morphine in their blood. Lactating mothers who are ultra-fast metabolizers have significantly higher levels of morphine in their milk.
The FDA states that nursing mothers have been using codeine safely for many years – it is considered as the safest option among narcotic pain relievers among nursing mothers and their infants by the medical profession. Nevertheless, the FDA is requiring makers of prescription codeine drugs to include data about codeine ultra-metabolism in drug package inserts. The FDA has also included
It is important that mothers who are taking narcotic pain relievers can identify signs of overdose in infants. A breast fed baby, who normally drinks his/her mother’s milk every 2 to 3 hours should not be sleeping for over four hours non-stop. A baby who is experiencing morphine overdose may be sleeping more and more, have difficulty breastfeeding, have breathing difficulties and appear limp.
About 1 to 28 people per hundred are ultra-rapid metabolizers. It is not known what the risk is of an adverse event for an ultra-rapid metabolizer who takes codeine. The only way an individual can find out is by doing a genetic test. An FDA-approved test does exist. However, it cannot, by itself, predict whether a mother’s milk will contain too much morphine if she is receiving treatment with codeine. Along with the test a doctor’s judgment is required, says the FDA.
— For more information, go to
“Pharmacogenetics of morphine poisoning in a breastfed neonate of a codeine-prescribed mother”
Gideon Koren, James Cairns, David Chitayat, Andrea Gaedigk, Steven J Leeder
The Lancet – Vol. 368, Issue 9536, 19 August 2006, Page 704
Written by: Christian Nordqvist