Milk concentrations following self directed cannabis use

Methods: The Lactation and Cannabis study observed 20 breastfeeding participants using cannabis at least weekly. Serial milk samples were collected around self-directed use to examine variation after single and repeated instances of consumption.

Findings: Milk THC concentrations varied markedly, and repeated use increased exposure. In the nine-participant single-use subset, the median time to the measured peak concentration was about two hours.

Limitations: Products and use patterns were not standardized. This small exposure study did not establish infant health effects or a reliable waiting interval that makes milk free of THC.