Fentanyl

It is a potent opioid analgesic chemically related to pethidine that is used in anesthesia and for the control of pain (cancer and chronic intractable). Several ways of administration: epidural, intravenous, intramuscular, intranasal, sublingual (transmucosal) or transdermal (patches). 

It is excreted into breast milk in undetectable or non-significant amount ^{(Cohen 2009, Goma 2008, Nitsun 2006, Steer 1992, Leuschen 1990, Madej 1987)}

Overall no problems have been observed among infants from treated mothers ^{(Cohen 2009)}. A 17-month-old infant whose mother received fentanyl, morphine, oxycodone, and benzodiazepines had lethargy/irritability, cyanosis, tachycardia, and respiratory depression that were reversed by naloxone. ^{(Beauchamp 2019)}

Plasma levels in one infant were undetectable. ^{(Cohen 2009)}

It has been authorized for treatment of small infants and neonates.

Fentanyl has a very low oral availability. After a mother has underwent anesthesia by the use of Fentanyl, she may breastfeed her baby as soon as her recovery and general conditions may permit it. ^{(Reece 2017, ASGE 2012)}

Fentany has lesser effect than Pethidine (Demerol) on initiation of breastfeeding. ^{(Fleet 2015)}

Fentanyl stimulates secretion of Prolactin, however, after Lactation has been established, Prolactin level has a poor relationship with production of mother's milk.

There is controversy ^{(Szabo 2013, Reynolds 2011, Camann 2007, Halpern 2005)} about the effect of analgesic medication used for labor management (Epidural anesthesia with Fentanyl added or not ) on the initiation and/or the duration of breastfeeding:

• A delay in the initiation of Lactogenesis II (milk coming in), delayed initiation of lactation, lower frequency and shorter duration of lactation have been found, particularly in mothers who had received high doses (>150-200 micrograms) of epidural fentanyl and in primiparous. ^{(Oommen 2021, Orbach 2019, Herrera 2015, Brimdyr 2015, Lind 2014, Beilin 2005, Jordan 2005)}
• Other studies have found no statistically or clinically significant differences. ^{(Fan 2020, Mahomed 2019, Fleet 2014, Zuppa 2014, Shrestha 2014, ​​​Gizzo 2012, Wieczorek 2010, Wilson 2010, Cohen 2009, Goma 2008, Chang 2005, Wang 2005, Radzyminski 2003)}

It appears to be of more paramount importance the women's support for the establishment and continuation of breastfeeding, than the negative effect that would be exerted by administration of analgesia or anesthesia during labor.
 ^{(Zuppa 2014, Torvaldsen 2006)}

It occurs a higher milk production and weight increase of the infant if there is an adequate pharmacological control of the pain that appears after vaginal birth or C-section. ^{(Wang 2005)}

Several medical societies and expert authors consider the use of this medication possible during breastfeeding. ^{(Hale, Briggs 2015, Schaefer 2015, AGA 2012, ASGE 2012, Howie 2006, Mahadevan 2006, Nice 2004, Lee 1993)}

The American Academy of Pediatrics says that is usually compatible with breastfeeding. ^{(AAP 2001)}