Docs Who Lift GLP-1s and Breast Milk: What the New Research Actually Found
Nov 19, 2025
Dr. Caitlin Crutch, a PharmD and PhD researcher specializing in lactation pharmacology, shares fascinating insights on drug transfer into breast milk. She reveals that semaglutide was undetectable in lactating women, while tirzepatide showed only trace amounts linked to lactation challenges. The complexity of drug transfer is underscored by tissue damage and the impact of GLP-1 medications on milk supply. Dr. Crutch emphasizes the importance of understanding these dynamics for the health of breastfeeding mothers and their infants.
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Large Molecules Hardly Enter Milk
- Large peptide drugs like GLP-1s rarely transfer into breast milk because the molecule is huge compared with milk barriers.
- Tissue damage, engorgement, or mastitis can allow small amounts to slip through but still usually remain negligible.
Measuring Drugs In Milk Is Technically Tough
- Human milk is a complex analytical matrix containing varied dietary components that complicate detecting tiny drug levels.
- High-resolution mass spectrometry and cross-disciplinary labs (e.g., veterinary dairy labs) can be essential for accurate measurement.
Call Volume Triggered GLP‑1 Research
- The Infant Risk Center runs a nurse phone line and apps and logs hundreds of thousands of queries about medications in pregnancy and lactation.
- Large spikes in calls about GLP-1s drove the center to start specific milk-transfer studies.