Yes, human breast milk naturally contains cannabinoids. Your body produces its own cannabis-like compounds called endocannabinoids, and these are present in breast milk at meaningful levels. This is separate from the question of whether THC or CBD from cannabis use transfers into milk, which also happens and is a different concern entirely.
Natural Cannabinoids in Breast Milk
Your body makes its own cannabinoid compounds that interact with the same receptors as THC and CBD. The most abundant one in breast milk is called 2-AG, found at concentrations around 59 nanograms per milliliter in women with a normal BMI. A second compound, anandamide, is also present but at levels 100 to 1,000 times lower than 2-AG, often too low to measure reliably.
These naturally occurring cannabinoids appear to play an important role in newborn feeding. Research in mice has shown that activating cannabinoid receptors is critical for initiating the suckling reflex, essentially helping the muscles around the mouth coordinate to latch and nurse. Without this signaling system functioning properly, newborns in animal studies failed to feed. The endocannabinoids in breast milk likely serve as one of the signals that encourage a baby to eat during those critical first days of life.
Body weight may influence how much 2-AG ends up in milk. Women with overweight or obesity had slightly higher average levels (around 65 to 66 ng/mL), though with much wider variation from person to person. This suggests that maternal fat tissue, which stores and releases these compounds, plays a role in determining the concentration.
How THC and CBD Transfer Into Milk
When a breastfeeding parent uses cannabis, THC and CBD also end up in breast milk, and they concentrate there at surprisingly high levels. THC accumulates to about seven times the concentration found in blood plasma. CBD shows a similar pattern, reaching roughly 2.6 times the plasma level. This happens because both compounds are highly fat-soluble, and breast milk is rich in fat, essentially acting as a reservoir.
The active breakdown product of THC (the metabolite that also produces psychoactive effects) does not accumulate in the same way. Its milk-to-plasma ratio is only 0.07, meaning very little of it transfers. But the THC itself is the primary concern, and it concentrates efficiently.
CBD data is more limited. In a study of 50 mothers who used cannabis and donated milk samples, the median CBD concentration was 5 micrograms per liter, with a range of 1.3 to 8.6. Notably, 42% of samples had CBD levels too low to measure. Mothers who used oil or smoked from a pipe tended to have higher CBD levels in their milk compared to those using joints, blunts, or edibles.
THC Stays in Milk for Weeks
One of the most important things to understand is how long THC persists in breast milk. A study from Children’s Hospital Colorado found that THC was still detectable in breast milk six weeks after mothers stopped using cannabis. Every woman in the study still had measurable THC at the end of the observation period, meaning the true clearance time could be even longer.
This persistence comes down to biology. THC dissolves readily into fat, and breast milk contains significant fat. In animal studies, daily THC use resulted in concentrations in fat tissue ten times higher than in any other part of the body, and the drug persisted in fat for two weeks even in rats, which metabolize substances faster than humans. The estimated half-life of THC in human breast milk is about 11 to 12 hours, but other models predict it could be as long as 39 hours. That translates to a full clearance window of roughly 2.5 to 8 days after a single use, longer with repeated use as THC builds up in body fat and releases slowly.
The amount that ends up in milk varies from person to person based on how much and how often they used, their metabolism, and their body composition. Heavier use and higher body fat both extend the timeline.
Why Pumping and Dumping Doesn’t Work
Unlike alcohol, which clears from milk as it clears from blood, THC cannot be effectively removed by expressing and discarding breast milk. Because THC is stored in fat tissue throughout the body and slowly released back into the bloodstream over days or weeks, new milk produced after pumping will still contain THC. The compound is continuously resupplied from the mother’s fat stores, not sitting in a fixed pool of milk waiting to be discarded. Pumping and dumping is only useful for substances that clear from the blood quickly.
What This Means for Infant Development
Research on how cannabinoid exposure through breast milk affects babies is still limited, and most studies have difficulty separating the effects of breastfeeding exposure from prenatal exposure during pregnancy. That said, the broader evidence on early-life cannabis exposure raises some concerns.
Children exposed to cannabis during pregnancy scored lower on cognitive development tests at 36 months, averaging 97.5 compared to 105 in unexposed children. They also showed lower composite motor skills scores. By age five, children with early cannabis exposure demonstrated measurably lower cognitive flexibility, scoring about 15 points below unexposed peers on that measure. These findings reflect prenatal exposure rather than breastfeeding exposure specifically, but they establish that cannabinoids during early development can influence brain function.
Some findings are contradictory. One study at 12 months found that exposed infants actually scored higher on gross motor skills and language measures. The picture is far from clear, and the quality of evidence varies significantly across studies.
What Medical Organizations Recommend
Both the American College of Obstetricians and Gynecologists and the American Academy of Pediatrics advise against cannabis use during breastfeeding, citing the limited safety data available. ACOG’s position, updated in 2025, states that there are no medical reasons to use cannabis during the postpartum period and that cessation should be encouraged.
However, both organizations also make an important distinction: continued cannabis use is not a reason to stop breastfeeding. The benefits of breast milk are well established, and the guidance is that breastfeeding should be encouraged regardless of cannabis use. The recommendation is to stop using cannabis if possible, not to stop nursing.
So breast milk contains two types of cannabinoids: the ones your body makes naturally, which appear to serve a biological purpose in infant feeding, and any THC or CBD introduced through cannabis use, which accumulate in milk at high concentrations and linger for weeks. The natural endocannabinoids are a normal part of human milk. The concern centers entirely on exogenous cannabinoids from cannabis products, which expose infants to compounds whose long-term developmental effects remain poorly understood.