New Dangers in Breastfeeding & Codeine Discovered

Breastfeeding new mothers (and those caring for them) who are taking a codeine-based pain relievers should take special note of this post.

Codeine is a strong pain reliever that is often prescribed to new mothers after an episiotomy or cesarian section. According to a scientific study to be released to the Canadian Therapeutic Congress in Toronto today, the Globe and Mail reported, some women carry multiple copies of a gene that causes them to rapidly metabolize the Codeine into morphine, that can be passed to infants through breast milk. In at least one case, an infant has died of morphine overdose.

Over 150,000 prescriptions for codeine are written to new Canadian mothers every year, and most of those prescriptions result in more relief than harm. But, if you carry multiple copies of the 2D6 gene, you liver enzymes rapidly change codeine into morphine.

The report states that about 1% of caucasions, 10% of Southern Europeans, and 30% of Eithiopians are suspected to carry duplicate copies of 2D6 gene. Signs that you may carry duplicates of the gene include severe drowsiness and constipation after taking Codeine. Unfortunately, these are also experiences most new mothers have as a result of giving birth. This is not a reason to stop nursing. This is a reason to stop taking codeine.

If you’re a nursing mother taking codeine for pain relief, watch your baby carefully. If s/he becomes more and more lethargic, seems to tired to be able to latch onto the breast, ask your doctor to test your milk and the baby’s blood for Morphine. If high levels are present, the baby may need an antidote called naloxone. The results of this study are so new that your doctor may not even know that the this problem has been discovered so be persistent. Also, if morphine is present in your milk, throw out any pumped milk you may have saved from when you were taking codeine. The good thing about metabolizing drugs quickly is that it should leave your milk quickly too. Just pump and toss the affected milk after you stop the drug.

I am forwarding this post to Dr. Hsein-Hsien Lei, B5 Media’s resident geneticist at the Genetics and Health blog. I hope she can tell us more about the duplicate 2D6 gene. (Edit note: see the comments to this post to review what Hsein had to say).

The problem with blogging this article is that the Globe and Mail puts new articles into its fee-for-use archive after a week. If you need more information and can’t access the article ten days or more from now, here is some more information to help you find it.The study was conducted by Dr. Gideon Koren at the Hospital for Sick Children as part of its Motherisk project. I’ll keep an eye on the press releases issued by the hospital and Motherisk to see if the study results will be available online in a more permanent, freely-accessed archive.