.svg)
What was once considered the discreet and "safer" alternative to smoking cannabis – the innocent-looking edible – is now at the centre of a burgeoning health crisis, with new research suggesting its risks may be far more insidious than previously understood. Despite their growing popularity, particularly in the UK where roughly one in 14 adults has tried them, experts warn that these seemingly harmless gummies and baked goods are presenting a "dark side" to cannabis consumption.
The UK's black market for cannabis, including edibles, continues to thrive, valued at an estimated ÂŁ2.6 billion annually. Meanwhile, the legal medical cannabis market in the UK is projected to reach ÂŁ300 million by 2025, with user numbers expected to surge to approximately 337,900 by 2024 from fewer than 250 in late 2019. This rapid expansion, however, is shadowed by alarming new findings.
Edibles: A Hidden Threat to Heart Health?
A groundbreaking study from the University of California, San Francisco (UCSF), published in May 2025, has sent shockwaves through the cannabis community. For the first time, researchers found that regular consumption of THC-containing edibles (three times a week) leads to a reduction in vascular function comparable to that seen in cigarette smokers – a decline of around half. Worryingly, this impact on blood vessel health was found to be worse than that observed in individuals who smoked cannabis regularly. The study, conducted between October 2021 and August 2024 on outwardly healthy individuals, highlights a significant increase in the risk of premature heart disease for edible users.
"The assumption that edibles are inherently safer than smoking cannabis doesn't always hold up," explains Dr. Deepali Misra-Sharp, a GP who has observed a notable increase in edible use among her patients, including older adults seeking relief for chronic pain, insomnia, and anxiety. Other cardiac concerns repeatedly linked to regular marijuana use, whether smoked, vaped, or eaten, include a 25% higher risk of heart attack and a 42% greater likelihood of stroke for daily users, according to a large 2024 study of over 430,000 adults.
The Problem of Dosing and Delayed Effects
One of the most critical dangers of edibles lies in their consumption method. Unlike smoking, the effects of edibles can take hours to manifest, leading many users to "stack" doses in impatience. "Many have displayed no real understanding of the dosing or onset time," notes Dr. Misra-Sharp. This often results in severe over-consumption, leading to "quite unpleasant episodes" such as intense anxiety, disorientation, vomiting, a racing heart, and in some cases, temporary psychosis or paranoia. The fat-soluble nature of THC also means its absorption is increased when consumed with fatty foods, such as the sweets and cakes commonly used in edibles, exacerbating these effects.
A Cocktail of Complications: Drug Interactions and Child Safety
Beyond immediate adverse reactions, edibles pose significant risks due to potential interactions with prescription medications. THC has been found to interact with nearly 400 drugs, including antidepressants and blood-thinners. Even CBD, often lauded for its non-psychoactive properties, can affect over 540 medications – a fact largely unknown to consumers. This oversight is particularly concerning for vulnerable groups like older adults or those managing pre-existing conditions.
Adding to the growing alarm, UK police forces have issued warnings about edibles being disguised as ordinary sweets and distributed to young people. Research published in Pediatrics indicates a "significant increase" in hospitalisations for children under six who inadvertently consume their parents' supply, mistaking them for candy, with almost 90% of these cases occurring within the home.
The Brain's Battle: Long-Term Mental Health Impacts
While the initial "dopamine high" is a draw, long-term THC consumption can blunt the brain's natural reward system, significantly increasing the likelihood of depression, mood swings, and suicidal thoughts. It also impairs memory formation and information processing.
Adolescents are particularly susceptible to the detrimental neurological effects of edible overconsumption, as their brains continue to develop until their mid-20s. Dr. Campbell, a mental health expert, reports a rising tide of cannabis-induced mental health issues. UK health services have linked the surge in psychosis patients to cannabis use, accounting for approximately a quarter of all admissions. A Canadian study earlier this year further demonstrated that the increasing potency of cannabis has directly contributed to a rise in schizophrenia cases.
Recent research, published in March 2025, has further illuminated how cannabis aggravates decreasing nerve connectivity in young adults at risk of psychosis. This study revealed a marked decrease in synaptic density, which was exacerbated by cannabis addiction, offering a crucial insight into why some users develop psychosis. Another study from May 2024 by the University of Bath highlighted that young people using high-potency cannabis between ages 16 and 18 were twice as likely to experience psychotic episodes between ages 19 and 24 compared to those using lower-potency varieties. Experts estimate that one in five new cases of psychosis across 11 European sites may be linked to daily cannabis use.
"The only real way to prevent it taking a serious toll is stopping it, if it’s not too late," Dr. Campbell urges. The consequences can be devastating, leading to an inability to work, sustain relationships, and in severe cases, trigger violent behaviour or dangerous delusions. Even with medication, the long-term damage of cannabis-induced paranoia can leave sufferers with a "sad, isolated kind of life."
The Promise of CBD: A Different Story
While THC-laden edibles pose significant threats, CBD (cannabidiol) products offer a different perspective. CBD, a non-psychoactive compound, is legal in the UK provided it contains less than 0.2% THC.
Research into CBD continues to expand. A 2021 review of 32 randomised controlled trials on medicinal cannabis and cannabinoids for chronic pain found small improvements in pain and physical functioning. It also noted small improvements in sleep but no consistent benefits for other quality-of-life measures. However, a 2025 report highlights that CBD is stepping into a new role "grounded in science, research, and therapeutic validation." Clinical trials are ongoing, with promising results for seizure reduction (e.g., a 41.1% average reduction in seizures in one trial) and even new FDA-approved Phase 2 clinical trials for a CBD-based drug to treat autism spectrum disorder. Health Canada is also proposing reclassifying CBD as a natural health product, which could significantly increase its accessibility over-the-counter.
While side effects like drowsiness and dry mouth are possible, they are generally mild. Yet, the warning about drug interactions remains pertinent, as CBD can affect numerous medications.
A Call for Greater Awareness
The escalating popularity of cannabis edibles, coupled with new scientific evidence, demands greater public awareness and more proactive conversations between healthcare professionals and patients. GPs are urged to routinely inquire about cannabis use, including edibles, to facilitate "honest, harm-reduction based conversations" and mitigate the growing health risks. The seemingly innocent sweet may be a bitterpill for public health.
