Cannabis, Pregnancy, Breastfeeding, Teens and Driving

Urgent first: a child has eaten cannabis

If a child may have eaten a cannabis edible, such as a gummy, call US Poison Help at 1-800-222-1222 right away. For severe symptoms or immediate danger, call 911. [1] Outside the US see poison help by country. NIDA says children eating edibles is a growing concern that usually happens by accident and can lead to hospitalization and serious illness. [1] A clinical review found that many young children admitted to hospital had been exposed to high-concentration products such as edibles, resins or vaping liquid, with sedation and slowed breathing among the effects. [2] Unintentional edible ingestions rise where cannabis is legalized and sold at retail. [3] Products containing delta-8 THC have also caused medical emergencies in children. [1]

How to read this page

This is education, not medical or legal advice. Evidence labels: approved medicine, established, mixed, insufficient evidence, evidence of harm. "Association" means two things were seen together, not that one proved to cause the other.

Pregnancy

What the largest review found. A 2025 systematic review of 51 studies (about 21 million participants) looked at cannabis use in pregnancy after adjusting for tobacco use. It found moderate-certainty evidence of higher odds of low birth weight (odds ratio 1.75), preterm birth (1.52) and being small for gestational age (1.57), and low-certainty evidence of higher perinatal mortality (1.29). [4] Label: evidence of harm (association).

What health agencies say. Health Canada says there is not enough research to identify a safe amount, that the safest choice is not to use cannabis when pregnant, and that edibles and vaping are not safer than smoking. It also says cannabis is not recommended to treat morning sickness. [5] NIDA reports that the American College of Obstetricians and Gynecologists recommends counseling women against using cannabis while trying to get pregnant, during pregnancy and while breastfeeding. [1]

CBD specifically. The FDA lists effects of CBD on the developing fetus and on breastfed newborns as unanswered questions. [6] The approved CBD medicine's label says that, based on animal data, it may cause fetal harm. [7] Label: insufficient evidence in people.

Breastfeeding

Health Canada says THC and CBD pass into breast milk, that THC can make a baby drowsy or have trouble latching and sucking, and that cannabis can remain in breast milk for days to weeks. It adds that expressing and discarding milk ("pumping and dumping") does not reduce cannabis in the milk. [5] The CBD medicine's label states that there are no data on whether CBD or its breakdown products are present in human milk. [7] The two sources differ on CBD, which shows how limited the research is. See also pregnancy and breastfeeding safety. Anyone who is pregnant or nursing should talk with a health care provider about any cannabis use, and no one should be judged for asking.

Teens and young adults

NIDA says adolescence is an important time for brain development. Regular, heavy use in adolescence has been associated with weaker working memory, processing speed, verbal memory and school performance. [1] Some evidence links cannabis use to earlier onset of psychosis in people with genetic risk. [1] NCCIH reports that adolescents who use cannabis are four to seven times more likely than adults to develop cannabis use disorder. [8] Label: evidence of harm (association) for regular heavy use. Minimum legal ages differ by place. In Canada, for example, the legal age is 18 in Alberta, 21 in Quebec and 19 in several others, such as British Columbia and Manitoba. [9] See children and teens safety for general guidance, and cannabis adverse effects for help-seeking.

Driving

Crash risk. A 2012 meta-analysis of nine studies found driving after cannabis was associated with higher odds of a crash (odds ratio 1.92), higher for fatal crashes, with large differences between studies. [10] A 2022 review of experimental driving studies found cannabis alone was associated with poorer lane control, and cannabis plus alcohol with greater impairment than either alone. [11] NIDA notes that cannabis is the drug most often found in drivers in crashes, but that a National Highway Traffic Safety Administration study found no significant added crash risk attributable to cannabis. [1] Label: mixed on size of risk; impairment of driving skills is established in experimental studies.

How long to wait. Justice Canada says the evidence does not yet allow general guidance on how much cannabis is unsafe before driving or how long to wait. [12] Eaten cannabis can take up to two hours to start and up to four hours for full effects. [13]

Law. In Canada it is an offence to have 2 ng or more of THC per ml of blood within two hours of driving, with a more serious offence at 5 ng or more, and no medical exemption. [12] Other places set their own rules; see cannabis laws by country.

CBD medicines. The approved CBD medicine's label advises patients not to drive or operate machinery until they know how it affects them. [7]