Is Tacrolimus safe while breastfeeding?
Here is what NIH LactMed, the U.S. National Library of Medicine's authority on medicines and breastfeeding, reports about Tacrolimus. This is a summary of that source — not our own verdict.
Effects on the breastfed infant
One infant was exclusively breastfed during maternal tacrolimus therapy throughout gestation to at least 2.5 months of age at which time the infant was developing normally physically and neurologically. An ultrasound examination of the infant's thymus was normal.[ 7 ] The National Transplantation Pregnancy Registry reported data gathered from 1991 to 2011 on mothers who breastfed their infants following organ transplantation. A total of 68 mothers with transplants (mostly kidney or liver) used tacrolimus while breastfeeding a total of 83 infants. Duration of nursing ranged from 1 week to 1.5 years and follow-up of the children ranged from weeks to 16 years. There were no reports of problems in any of the infants or children.[ 19 ] A review of the Transplant Pregnancy Registry International database from 1999 to 2024 found that 516 mothers with transplants had breastfed their infants for at least 4 weeks while taking tacrolimus.[ 20 ] The breastfed infants of six women who took tacrolimus during pregnancy for organ transplantation were breastfed (4 exclusive, 2 partial) for 45 to 180 days and followed for periods of 2 to 30 months. The mothers' mean daily tacrolimus dosage during breastfeeding was 9.6 mg daily (range 4.5 to 15 mg daily). Four mothers were also taking azathioprine 100 to 150 mg daily, one was taking diltiazem, and one was taking prednisolone 15 mg and aspirin 75 mg daily. None of the infants had any clear tacrolimus-related side effects, although one had transient thrombocytosis that resolved despite continued breastfeeding. Developmental milestones were normal and no pattern of infections was noted.[ 16 ] Two mothers with systemic lupus erythematosus were reported who took tacrolimus 3 mg daily during pregnancy and lactation as well as prednisolone 30 or 40 mg daily. Three years after birth, both children were healthy. The durations of lactation were not stated.[ 18 ] In a case series of women who had liver transplants over a 25-year period, one woma
Effects on milk supply
A study in renal transplant patients who were on a tacrolimus-based immunosuppression regimen found that women s median serum prolactin levels were 14.4 mcg/L compared with women who were not taking tacrolimus (17.6 mcg/L). The difference was statistically significant. Median serum testosterone levels (0.121 vs 0.137 mcg/L) and serum cortisol levels (82.5 vs 105 mg/L) were also significantly lower in the tacrolimus group.[ 27 ] The reduced prolactin may be caused by inhibition of the transcription of the human prolactin gene.[ 28 ] Not all studies have found a reduction in serum prolactin with tacrolimus.[ 29 ] The prolactin level in a mother with established lactation may not affect her ability to breastfeed.
Levels in milk
Maternal Levels. Random tacrolimus colostrum levels in 10 samples from 6 mothers averaged 1.7 mcg/L (range 0.3 to 1.9 mcg/L) which was about 50% of maternal serum levels. Tacrolimus dosages in these mothers were not reported.[ 6 ] One mother taking 3 mg twice daily (0.1 mg/kg per day), had a peak milk level of 0.57 mcg/L one hour after the dose. The half-life in milk was estimated to be 12.85 hours. The authors estimated that her breastfed infant would receive 0.06% of the maternal weight-adjusted dosage or 0.06 mcg/kg daily, which is 0.03 to 0.04% of the oral starting dosage for pediatric patients.[ 7 ] One mother who had been taking tacrolimus for a kidney transplant 5 years earlier was 3 months postpartum and exclusively breastfeeding her infant. She had been taking a dosage of 2 mg orally twice daily (0.05 mg/kg per day) for at least 2 months. She was also taking atenolol 100 mg, azathioprine 100 mg, diltiazem 180 mg, furosemide 20 mg, and prednisone 5 mg daily. Milk samples obtained over a 12-hour dosage interval found little change throughout the day, with the highest levels of 2.1 mcg/L at 4 and 8.5 hours after the dose. The average milk concentration was 1.8 mcg/L. The authors calculated that an exclusively breastfed infant would receive a daily dosage of 0.27 mcg/kg which is about 0.5% of the maternal weight-adjusted dosage and less than 0.2% of the pediatric dosage for organ transplant rejection.[ 8 ] Eleven women who took tacrolimus (exact dosages not specified but assumed to be 6 mg daily) during pregnancy and postpartum donated 22 breastmilk samples (times unspecified) for analysis. The median breastmilk concentration was 0.8 mcg/L (range 0.1 to 1.6 mcg/L). Two women took samples before and 4 or more hours after a dose; no difference in milk levels was seen. The authors estimated that the maximum dosage that an exclusively breastfed infant would receive would be 0.56 mcg daily, equivalent to 0.23% of the maternal weight-adjusted dosage. Additionally, co
Source: NIH LactMed (National Library of Medicine).
Educational summary of an authoritative source — not medical advice. Never start, stop, or change a medicine while breastfeeding without confirming with your doctor.