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

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Drugs and Lactation Database (LactMed®) [Internet].

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Last Revision: December 21, 2020.

Estimated reading time: 1 minute

CASRN: 18652-93-2

Drug Levels and Effects

Summary of Use during Lactation

Amounts of methohexital in milk are very small. Existing data indicate that no waiting period is required before resuming breastfeeding after a single dose of methohexital. Breastfeeding can be resumed as soon as the mother has recovered sufficiently to nurse. When a combination of anesthetic agents is used for a procedure, follow the recommendations for the most problematic medication used during the procedure.

Drug Levels

Maternal Levels. Nine women who were at least 1 month postpartum received between 120 and 150 mg of methohexital intravenously for induction of general anesthesia for bilateral tubal ligation. Milk samples were obtained in the recovery room after surgery, the evening of surgery and on the day after surgery. The highest milk level was found at 63 minutes after the dose in one woman. Milk levels 1 to 2 hours after the dose ranged from 100 to 407 mcg/L (n = 5); levels 2 to 4 hours after the dose ranged from 39 to 199 mcg/L (n = 4); levels 8 to 10 hours after the dose ranged from undetectable (<20 mcg/L) to 65 mcg/L (n = 9). Methohexital was not detectable in the breastmilk of any woman 24 to 48 hours after the dose. The authors estimated that the typical breastfed infant would receive a maximum single dose of 0.04 mg of methohexital in a 100 mL feeding 1 hour after the dose or between 0.1 to 0.8% of the maternal weight-adjusted dosage.[1]

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

Effects in Breastfed Infants

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

Effects on Lactation and Breastmilk

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

Alternate Drugs to Consider

Dexmedetomidine, Etomidate, Propofol, Thiopental


Borgatta L, Jenny RW, Gruss L, et al. Clinical significance of methohexital, meperidine, and diazepam in breast milk. J Clin Pharmacol. 1997;37:186–92. [PubMed: 9089420]

Substance Identification

Substance Name


CAS Registry Number


Drug Class

Breast Feeding


Anesthetics, Intravenous

Disclaimer: Information presented in this database is not meant as a substitute for professional judgment. You should consult your healthcare provider for breastfeeding advice related to your particular situation. The U.S. government does not warrant or assume any liability or responsibility for the accuracy or completeness of the information on this Site.

Copyright Notice

Attribution Statement: LactMed is a registered trademark of the U.S. Department of Health and Human Services.

Bookshelf ID: NBK501299PMID: 30000358


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