Cannabis and Breastfeeding: What Research Says About THC

A Growing Question in an Era of Expanding Legalization

As cannabis legalization spreads across the United States, a growing number of nursing parents find themselves asking a question that medical guidelines have historically answered with a blanket prohibition: is it safe to use cannabis while breastfeeding?

The answer, according to the latest body of research, is more nuanced than a simple yes or no — and the science is still catching up to the reality of how many parents are making these decisions right now.

What the Research Shows About THC in Breastmilk

The primary psychoactive component of cannabis, tetrahydrocannabinol (THC), does pass into breastmilk. That much is well established. What's less clear is how much reaches the infant and what effects, if any, it produces.

Studies have found that detectable amounts of THC can persist in breastmilk for anywhere from six days to more than six weeks, depending on the frequency and method of consumption. Notably, research conducted at Washington State University found that THC was detectable in breastmilk even when mothers abstained for 12 hours before nursing, suggesting that timing consumption around feeding schedules offers limited protection.

However, the actual amount transferred to infants appears to be quite small. Research published in clinical journals found that infants received an average of 0.07 milligrams of THC per day through breastmilk — for context, a common low-dose edible contains approximately 2 milligrams. The infant dose represents a tiny fraction of what the mother consumed.

The 2026 Developmental Outcomes Study

A particularly relevant piece of research published in 2026 examined developmental outcomes in infants with prenatal cannabis exposure and found that outcomes did not significantly differ based on whether the infant was breastfed. This study adds to a limited but growing body of evidence suggesting that the benefits of breastfeeding itself may offset potential risks from trace THC exposure.

That said, researchers are quick to emphasize what they don't know. Long-term neurodevelopmental effects of chronic low-level THC exposure through breastmilk remain poorly studied. The endocannabinoid system plays important roles in brain development, and how exogenous cannabinoids might influence those processes during infancy is an area where data remains sparse.

Why Parents Are Using Cannabis While Nursing

The Lactation and Cannabis (LAC) Study revealed that the vast majority of nursing mothers who use cannabis — 89 percent — do so for mental or physical health symptoms rather than recreation. The most commonly cited reasons include anxiety, depression, gastrointestinal symptoms, chronic pain, and post-traumatic stress disorder.

This finding complicates the conversation considerably. Many of these conditions are inadequately managed by medications considered safe during lactation, and some parents view cannabis as a less harmful alternative to prescription pharmaceuticals that carry their own risks of passing into breastmilk.

The LAC Study also found that many nursing parents make decisions about cannabis use with minimal input from their healthcare providers. Instead, they rely on friends, online communities, and product marketing — sources that may or may not reflect current scientific understanding.

What Professional Guidelines Currently Recommend

Medical organizations including the American Academy of Pediatrics, the American College of Obstetricians and Gynecologists, and the Academy of Breastfeeding Medicine uniformly recommend that nursing parents avoid cannabis. Their positions are grounded in the precautionary principle: because long-term data on infant outcomes is insufficient, abstinence is the safest course.

The disconnect between official guidelines and actual behavior is significant. Survey data consistently shows that a meaningful percentage of nursing parents use cannabis despite these recommendations, creating a gap between clinical advice and lived experience.

CBD: A Different Equation?

While THC receives the most attention, many nursing parents are interested in CBD products, which don't produce intoxication. The research landscape for CBD and lactation is even thinner than for THC, with very few studies examining CBD transfer through breastmilk or its effects on nursing infants.

What is known is that CBD products vary enormously in quality and may contain undisclosed THC, heavy metals, or pesticides. For nursing parents considering CBD, third-party tested products from reputable manufacturers represent the minimum standard for risk reduction.

The Harm Reduction Conversation

Some clinicians are beginning to shift toward a harm-reduction framework rather than an abstinence-only message. This approach acknowledges that some parents will use cannabis regardless of guidelines and focuses on strategies to minimize potential risks: using lower-potency products, avoiding smoking (which introduces combustion byproducts), spacing consumption as far from nursing as possible, and maintaining open communication with pediatricians.

This perspective remains controversial within the medical community. Critics argue that harm-reduction messaging may be interpreted as implicit approval, while proponents counter that shaming parents into silence about their cannabis use leads to worse outcomes than honest, informed dialogue.

What We Still Don't Know

The most honest assessment of the current evidence is that significant gaps remain. Large-scale, long-term studies tracking developmental outcomes in breastfed infants whose mothers used cannabis are essentially nonexistent. The ethical challenges of conducting such research — you can't randomly assign nursing parents to use cannabis — mean that the evidence base will likely rely on observational studies for the foreseeable future.

Additionally, the rapidly evolving cannabis product landscape complicates research. Concentrates and high-potency edibles deliver dramatically different THC loads than the cannabis flower studied in earlier research, and findings from one era may not apply to products available today.

The Bottom Line for Nursing Parents

The current state of evidence doesn't support declaring cannabis use during breastfeeding safe, but it also doesn't conclusively demonstrate harm at the exposure levels documented in studies. Parents making these decisions deserve access to accurate, non-judgmental information rather than reflexive prohibition.

Having an honest conversation with a healthcare provider about cannabis use during lactation is arguably the single most important step a nursing parent can take. The quality of that conversation depends on providers who are informed about the current evidence and willing to engage without stigma — and on parents who feel safe enough to disclose their use.

As Schedule III reclassification opens doors to more cannabis research, studies specifically examining lactation and infant outcomes should be a priority for investigators. Until that data exists, uncertainty will remain the defining feature of this conversation.