Vitamin B6

The approved indications for vitamin B6 are exclusively related to vitamin B6 deficiency due to inadequate diet, drug-induced deficiency, such as isoniazid (INH) and oral contraceptives, and due to inborn errors of metabolism, such as seizures or vitamin B6-dependent anemia.
Off-label indications to treat neuropathies and radicular, back, sciatic and carpal tunnel pain (Geller 2016, Mibielli 2009) lack sufficient scientific evidence (Ang 2008, O'Connor 2003).

Daily requirements of Vitamin B6 are between 2 to 3 mg per day (Sauberan 2019, Ares 2015, Hall 2010, Chang 2002, Bender 1989). With a varied and balanced diet you do not need supplements containing this vitamin. Its deficiency is very rare because it is widely found in food.

Excessive doses (more than 50-100 mg/day) and doses taken over prolonged periods (months versus years), such as those used in off-label indications, can cause neuropathies and other neurological problems in people who take them (van Hunsel 2018 , ADRAC 2008, Bender 1989, Waterston 1987, Dalton 1987, Schaumburg 1983).

Vitamin B6 is found in breastmilk at a concentration of between 0.005 to 0.25 mg/L (Sauberan 2019, Hampel 2017, Lawrence 2016 p299, Ren 2015, Roepke 1979) and is higher in mature milk (0.1 to 0.25 mg/L ) than in transitional milk and in colostrum (0.01 to 0.02 mg/L).

The concentration of vitamin B6 in breastmilk increases with supplements in the diet or from treatments with Vitamin B6 (Sauberan 2019, Hampel 2017, Chang 2002, Ooylan 2002, Chang 1990, Styslinger 1985, Thomas 1980 and 1979, Roepke1979, West 1976).
The high plasma protein binding of vitamin B6 hinders excretion in breastmilk, so it is very unlikely that supplementation will reach therapeutic levels that may affect the infant (milk levels would need to be 200 times higher than usual).
Problems have never been reported in infants breastfed by mothers taking Vitamin B6.

If supplements are needed due to deficiency or inadequate diet, it is not advisable to exceed 40-100 mg daily during breastfeeding (Sauberan 2019, van Hunsel 2018, Hale 2017 p.817, Ares 2015).

There is insufficient evidence and contradictory reports on the ability of pyridoxine in high doses to inhibit prolactin secretion and nullify milk production (AlSaad 2017, Anderson 2017, Oladapo 2012, Pepperell 1986, Andon 1985, Scaglione 1982, Vecchione 1980, Greentree 1979, de Waal 1978, Lehtovirta 1978, Macdonald 1976, Canales 1976, McIntosh 1976, Marcus 1975, Foukas 1973).
Milk production shoud therefore be monitored if Vitamin B6 is administered at higher doses than required daily.

Various medical associations, experts and expert consensus consider the use of this medication to be safe during breastfeeding (Hale 2017 p 817, Briggs 2017).
American Academy of Pediatrics: medication usually compatible with breastfeeding (AAP 2001).
List of essential medicines WHO: compatible with breastfeeding (WHO 2002).