Legal Doesn’t Mean Harmless: What Long-Term Cannabis Users Wish They Knew

As cannabis becomes legal and easier to buy in more parts of the world, a growing body of research is drawing attention to a key difference that can get lost in the legalization debate: A drug being legal does not automatically make it harmless. A major global review has found that health risks may depend not only on whether cannabis is legal, but also on how governments allow it to be sold.

The University of Bath-led analysis, published in The Lancet Psychiatry, examined changes in cannabis policies around the world between 2000 and 2025. Researchers found little evidence that simply removing criminal penalties for possession, or allowing cannabis under tightly controlled systems, increased overall use.

However, commercial markets where companies sell cannabis for profit, including those in parts of the United States and Canada, were linked to increased consumption, stronger products, and higher rates of cannabis addiction.

The findings add a wider public health perspective to the experiences of people who began using cannabis when they were young and later struggled with its effects. Their stories raise a question that becomes more important as cannabis use becomes more socially accepted: Are people receiving enough information about the risks before they start?

One User’s Experience Shows the Personal Side

In a recent first-person account published by The Washington Post, writer Monica Romano described starting cannabis at age 13 and continuing to use it regularly for nearly two decades.

For Romano, cannabis initially offered relief from anxiety and problems at home. But over time, she said, what began as a way of coping became difficult to leave behind.

“The drug didn’t give me a voice. It just quieted the one telling me I didn’t deserve to be heard,” Romano wrote.

Her experience does not mean that everyone who uses cannabis will develop the same problems. However, experts have raised particular concerns about frequent use that begins during adolescence, when the brain is still developing.

Riley Guinan, a physician assistant and adolescent substance use specialist at Zellig Psychiatry, told The Washington Post that the effects of long-term use can go beyond the direct impact of a drug on the brain.

“Sometimes the most durable consequence of heavy adolescent cannabis use is not a persistent direct neurochemical injury but the way it shaped development, opportunities, coping style, and identity,” Guinan said.

Romano’s account also points to an issue that can be overlooked as cannabis becomes more accepted: Some people may use it to manage anxiety, stress, or other problems without addressing the reasons behind those feelings.

That concern becomes especially important for young users, who may develop habits around cannabis before learning other ways to manage stress.

Not All Legal Cannabis Systems Have the Same Results

The new global analysis suggests that the debate cannot be reduced to a simple choice between prohibition and legalization.

Uruguay, for example, has a tightly controlled legal system. Adults can obtain a limited selection of cannabis products through pharmacies, cannabis clubs, or home growing, while restrictions are placed on factors such as product strength.

Researchers found little evidence of significant increases in cannabis use following tightly regulated legalization in such settings.

The picture was different in commercial markets.

In Canada and many U.S. states, cannabis is sold through large legal markets where companies compete for customers. Researchers found that cannabis use increased following commercial legalization, while products also became more potent. Adult cannabis addiction increased as well.

“In a rapidly changing global cannabis policy landscape, it is increasingly important to ask how policy will change, rather than if it will change at all,” said Tom Freeman, a professor at the University of Bath and co-author of the analysis. “The type of policy change is critical.”

The comparison suggests that legal access alone may not be the main issue. How widely cannabis is available, how strongly products are marketed, and how much THC they contain may also shape the risks.

“The emergence of a for-profit cannabis industry can result in commercial interests being prioritized over public health, just as we have seen with the alcohol and tobacco industries,” Freeman said.

That comparison is important because alcohol and cigarettes are both legal for adults, but neither is considered risk-free. Public health warnings, age restrictions, and other controls exist because legal status is not the same as medical safety.

Cannabis may require a similar distinction.

Dependence and Mental Health Risks Remain Concerns

The University of Bath-led review also found that commercial legalization was followed by increases in cannabis addiction and hospital admissions involving psychosis, including cases where psychotic disorders occurred alongside cannabis addiction.

A separate review in the same collection of research found evidence that daily cannabis use can combine with other risk factors to increase the likelihood of psychosis. However, researchers said the evidence connecting cannabis with depression, anxiety, and suicidal thoughts or suicide was less clear.

This distinction is important. Research does not show that every person who uses cannabis will develop a mental health condition. Individual risk can depend on factors including frequency of use, age, product strength, and a person’s existing vulnerabilities.

Young users may face additional concerns.

Annina Beus, a pediatrician writing for the Connecticut Mirror, warned that regular adolescent cannabis use has been linked with problems involving attention, memory, learning, and executive functioning. She also highlighted cannabinoid hyperemesis syndrome, a condition that can cause repeated episodes of severe vomiting and abdominal pain among some regular users.

“Legal does not mean risk-free, particularly for developing adolescents,” Beus wrote.

Cannabis can also lead to dependence. People who begin using during their teenage years may face a greater risk of increasing their use or developing dependence later in life, according to Beus.

Medical Cannabis Is a Separate Question

The growing use of cannabis for medical purposes adds another layer to the discussion.

Medical cannabis used under professional supervision is different from recreational use, particularly when doctors control the dose and monitor a patient’s response. But the University of Bath researchers warned that poorly regulated medical cannabis systems could also carry risks when products are made widely available without strong evidence of their safety and effectiveness for particular conditions.

Another review of 54 clinical trials found limited benefits from cannabinoids for some conditions. Researchers reported modest benefits for cannabis withdrawal and use, insomnia, tics, and some autism traits. However, they found no meaningful benefit in the available trials for anxiety, post-traumatic stress disorder, psychosis, or opioid dependence. No trials examining cannabinoids as a treatment for depression were identified.

The findings do not mean cannabis has no medical value. Instead, they underline the need to examine specific treatments and conditions rather than treating “medical cannabis” as a single medicine with proven benefits for every health problem.

The Question Is Not Simply Legal or Illegal

The emerging evidence points toward a more complex discussion about cannabis.

The University of Bath analysis found that decriminalization, which removes or reduces criminal penalties without creating a large commercial market, showed little evidence of increasing cannabis use. Tightly regulated legalization produced similar findings. The clearest increases in use and addiction appeared in commercial systems where cannabis was widely available for profit.

“Alternative policies, such as decriminalisation or strictly regulated legalisation, can remove the harms of criminalizing people who use cannabis, while limiting changes in use,” Freeman said.
For long-term users such as Romano, however, the policy debate is only one part of the story. Her experience raises a more personal question about what people know when they first encounter cannabis, particularly at a young age.

As cannabis becomes more widely available and socially accepted, public health experts say the conversation does not need to return to fear or stigma. But greater acceptance should not replace clear information about dependence, product strength, and possible mental and physical health effects.

The experience of alcohol and tobacco offers a familiar comparison. Both are legal, yet decades of research have shown that legal products can still carry serious risks. The growing evidence around cannabis suggests that legalization and health safety should also be treated as two separate questions.