In: Drugs and Lactation Database (LactMed®) [Internet]. Bethesda (MD): National Institute of Child Health and Human Development; 2006.


Because of the low levels of isoniazid in breastmilk and safe administration directly to infants, it is unlikely to cause adverse reactions in infants, but infants should be monitored for rare instances of jaundice. Giving the maternal once-daily dose before the infant's longest sleep period will decrease the dose the infant receives. The amount of isoniazid in milk is insufficient to treat tuberculosis in the breastfed infant. If breastfed infants are treated with isoniazid, they should also receive pyridoxine 1 mg/kg daily.[1] The Centers for Disease Control and Prevention and other professional organizations state that breastfeeding should not be discouraged in women taking isoniazid.[2]

All nursing mothers who are taking isoniazid should take 25 mg of oral pyridoxine daily.[2] A study of nursing African mothers with concurrent HIV and tuberculosis infections found that those receiving isoniazid had an increased risk of niacin deficiency (pellagra). The authors suggested that a multivitamin supplement might be advisable during isoniazid therapy in populations with undernutrition.[3]

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