Botulinum Toxins, Therapeutic and Breastfeeding

Summary of use during lactation

Of the therapeutically used botulinum toxins, only onabotulinumtoxinA has been studied during breastfeeding and only in cosmetic doses. It was not detectable in the milk of two women and detectable in only minute amounts in 5 others after 40 to 92 units injected into the face. Many mothers have breastfed their infants after injection of onabotulinumtoxinA for migraine. International guidelines considers onabotulinumtoxinA acceptable in breastfeeding women with chronic migraine, and it is often used in nursing mothers by dermatologists.[1-3] High doses for other conditions have not been studied.

Drug levels in milk and infant serum

Maternal Levels. Four women undergoing cosmetic procedures were injected with doses ranging from 40 to 92 units of onabotulinumtoxinA. Milk samples were taken at baseline and 1, 3 and 5 hours after the injections. Two women had undetectable (<46 ng/L) levels in all samples after receiving 54 and 92 units. Two other women who received 40 and 46 units had peak milk levels of 422 ng/L and 747 ng/L, respectively.[4] Three women were reported who received onabotulinumtoxinA at 3 sites for facial cosmetic procedures for a total dose of 64 units each. They were instructed to express 200 mL of breastmilk before treatment and 1, 6, 24, 36, 48, and 72 hours after treatment using a manual pump. In addition, milk samples were collected at 5, 6, 7, 10, and 11 days, 2 months, 4 months, 5 months and up to 1+ year after the injections. The highest concentration observed of 167 ng/L was in a sample from one woman 4 days after the injection. Levels were highest overall in the first week (82.45 to167 ng/L). After the first week, circulating BoNT/A concentrations decreased before another peak of 132.7 ng/L occurred at 2 months after the dose.[5] If the highest concentration and a dose of 150 mL/kg daily breastmilk intake are used, a breastfed infant would receive a maximum of 5 ng/kg of botulinum toxin A orally per day. Infant Levels. Type A botulinum toxin was detected in the blood and stools of a nursing mother after ingesting fermented salmon eggs. No botulinum toxin was detected in the breastfed infant's blood or stool on the day the mother was admitted to the hospital (3 days after the onset of illness) and no botulism organisms were detected in the infant's stools.[6]

Effects in breastfed infants

One mother breastfed her infant while she was experiencing toxicity from botulism poisoning. She breastfed her 2-month-old infant. Although the mother died, the infant had no symptoms.[7] A woman developed botulism after ingesting fermented salmon eggs while breastfeeding her 8-month-old breastfed (extent not stated) infant. The infant developed no signs or symptoms of botulism even though she continued to nurse throughout the mother's hospitalization.[6] A single-center study reported 94 women who received onabotulinumtoxinA injections for chronic migraine while breastfeeding their infants. No adverse reactions were reported in the breastfed infants over the first year postpartum.[8] A mother who was nursing a 2.5-year-old toddler received a treatment for facial wrinkles consisting of an injection of a single vial containing 85 units of “Botox” (onabotulinumtoxinA, manufacturer unknown) from a Chinese product that apparently is not sold in the United States. Two days later, her daughter experienced swelling in her mouth with prominent swelling of the upper lip. The article’s authors felt that the swelling was caused by the botulinum toxin in milk, but no specific evidence linked the swelling to the botulinum toxin other than the time course.[9]

Effects on lactation and breastmilk

Relevant published information was not found as of the revision date.

Alternative drugs to consider

(Migraine Prophylaxis) Divalproex, Erenumab, Metoprolol, Nortriptyline, Propranolol, Rimegepant, Topiramate, Valproic Acid

References

1. Puledda F, Sacco S, Diener HC, et al. International Headache Society Global Practice Recommendations for Preventive Pharmacological Treatment of Migraine. Cephalalgia 2024;44:333102424126973539262214 PubMed
2. Ornello R, Maassen van den Brink A, Puledda F, et al. Migraine management during pregnancy, breastfeeding and in women planning pregnancy. Cephalalgia 2025;45:333102425139394541263702 PubMed
3. Cucalon J, Taylor D, Tolkachjov SN, et al. Practice versus protocol: A survey of current botulinum toxin use during lactation and pregnancy in dermatology. Dermatol Surg 2025.1076-051240366010 PubMed
4. Hudson C, Wilson P, Lieberman D, et al. Analysis of breast milk samples in lactating women after undergoing botulinum toxin injections for facial rejuvenation: A pilot study. Facial Plast Surg Aesthet Med 2024;26:523-638306172 PubMed
5. Gu H, Xu Z, Koviazina R, et al. Detection of nontoxic BoNT/A levels in post-facial botox injection breastmilk. Front Drug Saf Regul 2025;4:1480515.doi:10.3389/fdsfr.2024.148051540979397 PubMed
6. Middaugh J. Botulism and breast milk. N Engl J Med 1978;298:343622098 PubMed
7. Douthirt C. An outbreak of botulism in Tucumcari, New Mexico. Southwest Med 1938:51-3
8. Wong HT, Khan R, Buture A, et al. OnabotulinumtoxinA treatment for chronic migraine in pregnancy: An updated report of real-world headache and pregnancy outcomes over 14 years in Hull. Cephalalgia 2025;45:333102425132738740326040 PubMed
9. Qin M, Liang Y, Yao J, et al. Swollen lips in young toddler during breastfeeding following a woman's botulinum toxin injection. J Craniofac Surg 2025;36:e1197-e940900164 PubMed