Cannabis Harms, Benefits Described In New Public Health Statements - 11/05/26

Cannabis harms, benefits described in new public health statements

OHA revises, expands statements published after Measure 91 passage in 2014

PORTLAND, Ore.—Oregon Health Authority has published updated public health statements offering guidance to clinicians, local public health agencies, legislators and the public on the potential harms and benefits of cannabis use.

Based on extensive review of scientific literature and key reports from around the world, the 2026 Cannabis Public Health Statements expand and revise previous statements an OHA-convened Retail Marijuana Scientific Advisory Committee developed in 2015. The earlier statements, which were updated in 2017, were created following the 2014 passage of Measure 91, which legalized recreational marijuana use, sale, and possession.

Cannabis policy and science has changed considerably since 2017. “We set out to capture as much recent data and evidence as possible, from hundreds of studies and reports, to provide a comprehensive picture of the potential health harms and health benefits of cannabis use,” said Tom Jeanne, M.D., M.P.H., deputy state health officer and epidemiologist at the OHA Public Health Division.

The statements are for educational purposes and are not a substitute for medical care or consultation with a health care professional. 

The summary accompanying the statements describes cannabis terminology, cannabis products and potency, how cannabis is consumed, and recommendations for individuals considering cannabis use. The summary also offers guidance on interpreting the public health statements, including cautioning that health outcomes described as “linked to” or having an association with cannabis use or exposure do not prove causation.

The statements’ findings include moderate or strong evidence linking cannabis use and health harms. Those include:

• Respiratory health—Respiratory diseases and symptoms related to particulate matter in smoke; chronic bronchitis from heavy smoking; e-cigarette or vaping product use-related lung injury.
• Cardiovascular and metabolic health—Heart attack and stroke; cancer; pre-cancerous changes in the lungs, related to cancer-causing chemicals present in cannabis smoke (both firsthand and secondhand smoke); testicular cancer.
• Injuries—Motor vehicle crashes when driving after cannabis use; severe burn injuries from vaporizing device failures and home butane extraction of hash oil; toxicity and poisoning, sometimes requiring emergency department visits or hospitalization.
• Neurological health—Impairments in memory, attention, decision making, and learning; up to a month after use for frequent cannabis use.
• Mental health and substance use—Suicide; psychosis, including schizophrenia, especially people with long-term use, adolescents, and people using high-THC products; cannabis use disorder from frequent cannabis use and use of high-THC products; worsening of bipolar disorder.
• Reproductive health and early child development—Fetal health effects from maternal use during pregnancy, including infants being born small for gestational age or with low birthweight; attention problems, reduced cognitive function, and decreased academic ability and IQ scores in children after maternal use during pregnancy.
• Cannabis use in childhood and young adulthood—Low academic achievement, such as not graduating from high school; developing cannabis use dependence or disorder as an adult; high-risk use of alcohol, tobacco, and other drugs as an adult; increased psychotic symptoms and disorders such as schizophrenia in adulthood, from regular use; depression, suicidal thoughts, and suicide attempts; poisoning of children consuming cannabis edibles, causing severe health effects that may require hospitalization.
• Other health topics—Gastrointestinal effects, including nausea, vomiting, and diarrhea; long-term use is associated with cannabis hyperemesis disorder (severe, re-occurring vomiting).

Findings of moderate or strong evidence linking cannabis use and health benefits included:

• Respiratory conditions—Short-term improvement of airflow in the lungs.
• Cancer—Treatment for chemotherapy-induced nausea and vomiting with pharmaceutical THC (dronabinol).
• Neurological health—Treatment for specific types of seizure disorders or epilepsy (pediatric Dravet syndrome, Lennox-Gastaut syndrome, and tuberous sclerosis complex) with pharmaceutical CBD (Epidiolex); treatment for multiple sclerosis (MS) spasticity symptoms with pharmaceutical nabiximols; improvements in chronic pain in adults, especially with oral or sublingual cannabinoids (nabiximols, nabilone, dronabinol)

The summary describes limitations with some of the Cannabis Public Health Statements, noting that “A few health statements are listed that have ‘insufficient evidence’ because they were included in other major reviews or prior Oregon health statements.” The summary also points out that “Due to the evolution of cannabis products, and lack of clarity in the research, actual risks could vary by product type (for example, smoked, edible, or vaporized), and by the amount of THC, CBD, and other ingredients or additives in products.”

In addition, according to summary authors, the review was conducted with a small team of OHA staff with limited resources, and as such, “our approach was not as in depth as a very large review, such as reviews by the Cochrane Collaboration or the National Academies of Sciences, Engineering, and Medicine.”

“Although we aimed to conduct a comprehensive review, these findings should not be taken to be exhaustive and representative of the entire body of cannabis health effects research, which is constantly expanding,” summary authors wrote.

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