Last update: Nov. 3, 2018
Not risky for breastfeeding or infant.
An antiinfective from the imidazole family indicated in the treatment of giardiasis, amebiasis, trichomoniasis and anaerobic infections (bacteroides and clostridium).
Oral administration one to three times a day. Intravenous use in severe cases.
Authorized and widely used in pediatrics. The dose for babies under two months is 15 mg/kg/day and for those older than two months it is 30 mg/kg/day (AEMPS 2018).
There are old studies that showed carcinogenic effects in rats receiving high doses. This has not been demonstrated in humans (Falagas 1998, Fahrig 1997, Beard 1988, Roe 1985), there still being a great deal of controversy (Adil 2018, Friedman 2009) and metronidazole is one of the most used antibiotics in vaginal, intestinal and other infections and whose use in humans is spreading (Adil 2018, Sobel 2015).
It is excreted in breastmilk in moderate but clinically insignificant amounts (Zhang 1997, Passmore 1988, Heisterberg 1983, Erickson 1981, Gray 1961).
No problems have been observed in infants whose mothers were taking it (Passmore 1988, Gray 1961), except for a possible case of diarrhea (Clements 1980). Plasma levels in these infants are undetectable or very low (Passmore 1988, Gray 1961).
Metronidazole can turn body fluids red and give a bitter or metallic taste to milk (Chin 2001, Andersson 1981), without this being detrimental. Although opinions are divided (Huang 2016), being contraindicated for some (van der Woude 2015 and 2010, Nielsen 2014, Yarur 2013), various medical associations, experts and expert consensus consider its use to be safe during breastfeeding ( Hale 2017 p 647, Schulze 2014, Kong 2013, Rowe 2013, Bar-Oz 2003, Einarson 2000, Rubin 1986). When the dose is large, some authors recommend waiting 12 to 24 hours after administration before breastfeeding in order to minimize exposure (Damas 2015, Huang 2014, Rowe 2013, CDC 2010, WHO 2002).
When it comes to mothers of premature or newborn babies, who are unable to metabolize metronidazole well, it may be prudent either to use the minimum effective dose or to seek an alternative.
Suggestions made at e-lactancia are done by APILAM´s pediatricians and pharmacists, and are based on updated scientific publications.
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