Is melatonin safe while breastfeeding?

What does the evidence say about melatonin while breastfeeding?

1. Short-term use of usual melatonin doses in the evening by a nursing parent is unlikely to adversely affect a breastfed infant, though some authors advise against it given the lack of data and a relatively long half-life in preterm newborns. 1
2. Melatonin occurs naturally in human milk on a daily rhythm, averaging about 23 ng/L between 2 and 4 am and dropping to undetectable in daytime milk. 1
3. One 18-month-old with bleeding episodes since birth and abnormal platelet aggregation improved after the nursing parent stopped taking a melatonin supplement. 1
4. Melatonin supplements are regulated differently from prescription medicines and have not been well studied for use while breastfeeding. 2
5. Federal supplement guidance advises caution about taking dietary supplements beyond a standard prenatal supplement while pregnant or nursing, because many have not been well tested for safety in this group. 3

How melatonin changes by nursing stage

• Early weeks. Sleep is at its worst and the temptation is highest, but this is also the stage with the least margin. Newborns, and preterm babies especially, clear melatonin slowly.
• Established nursing. Occasional evening use is the scenario the references describe as unlikely to cause trouble. Regular nightly use is a different question and belongs with your provider.
• Weaning. Exposure through milk falls as sessions drop. If sleep is still broken at this point, the underlying cause is worth looking at rather than the dose.