A long-awaited change in drug policy could pave the way for scientists to explore the benefits and risks of marijuana, the most widely used federally prohibited substance.

On Thursday, President Donald Trump signed an executive order aimed at reclassifying marijuana from a Schedule I substance to a Schedule III substance, a move initiated during the Biden administration.

“Decades of federal drug control policy have overlooked the medical applications of marijuana,” states the order. “This oversight hampers scientists and manufacturers in conducting essential safety and efficacy studies to inform healthcare providers and patients.”

This reclassification is expected to enhance research into medical marijuana, without federally legalizing the substance. However, marijuana use in the U.S. is rising significantly. Gallup data suggests that 15% of adults may smoke marijuana in 2023 and 2024, an increase from 7% in 2013.

The poll did not differentiate between medical and recreational use, revealing the highest usage (19%) among 18- to 34-year-olds—an age group that has exhibited concerning psychological side effects from cannabis use. A recent study published in the journal Pediatrics indicated that even infrequent use was linked to increased psychological distress and lower academic performance in teens.

Medical marijuana is often prescribed for chronic pain relief, to manage nausea and vomiting in cancer patients undergoing chemotherapy, and to stimulate appetite in individuals with specific medical conditions. It remains uncertain how rescheduling cannabis will impact funding for recreational cannabis research.

Scientists like Ziva Cooper are hopeful that reclassification will transform public health through in-depth marijuana research.

“Studying cannabis, also known as marijuana, for both its therapeutic and side effects has been very challenging,” said Cooper, director of the Center for Cannabis and Cannabinoids at UCLA. “The rapid evolution of this industry often outpaces consumer behavior and research developments.”

“It’s challenging to study, and as a scientist committed to public health, it’s tough to keep up with the shifting landscape.”

Schedule I is the most restrictive category within U.S. drug scheduling recognized by the Drug Enforcement Agency (DEA), applying to substances with “no currently accepted medical use and high abuse potential,” such as ecstasy and heroin. Schedule III substances, which include ketamine and anabolic steroids, are classified as having a “moderate to low potential for physical and psychological dependence.”

Even in cannabis-friendly regions, Cooper acknowledges that he faces similar research obstacles as those in states like Idaho, where cannabis use is prohibited.

“Researchers are unable to test readily available products; they can only inquire about basic characteristics of the cannabis available at compounding pharmacies visible from their lab,” Cooper said. “This creates limitations on sourcing the cannabis for research.”

Need for Thorough Research on Marijuana’s Benefits and Risks

Last year, the National Institutes of Health allocated $75 million for cannabinoid research, a slight increase from $70 million in 2023. Moreover, $217 million was directed towards cannabinoid studies, with $53 million specifically for cannabidiol (CBD), a non-psychoactive cannabinoid.

Dr. Brooke Wurster, medical director of the master’s in medical cannabis science and business program at Thomas Jefferson University, pointed out that bureaucratic challenges often confine cannabis research to observational studies rather than the rigorous clinical trials required for pharmaceuticals, resulting in mixed findings.

For instance, a study published in 2024 in the journal Current Alzheimer’s Research found a 96% reduced risk of subjective cognitive decline among recreational cannabis users aged 45 and older compared to non-users. In contrast, 2025 research in the JAMA Network Open indicated that heavy cannabis users aged 22-36 exhibited memory impairments.

A recent study in Biomedicine suggested cannabinoids as a “promising” alternative for opioid use in chronic pain management, emphasizing an urgent need for large-scale randomized controlled trials. Meanwhile, a study last year found that JAMA Network Open reported increased medical visits for cannabis-related disorders among older Medicare beneficiaries from 2017 to 2022.

The reclassification will enable researchers to examine and prepare specific marijuana formulations, Wurster noted. Even in states with medical cannabis programs, cannabis quality and potency can vary significantly across dispensaries.

“We can comprehensively monitor immediate symptoms, blood levels, and long-term effects,” she explained. “All the essential elements required for drug research mandated by the federal government.”

While cannabis has medical benefits for some individuals, Jonathan Caulkins, H. Guyford Steever Professor of Operations Research and Public Policy at Carnegie Mellon University, cautioned that administrative barriers alone do not account for cannabis not being a “miracle cure” for conditions like cancer and Alzheimer’s.

“Studies conducted in countries like Canada, France, and Israel are not under the same restrictions,” Caulkins stated. “We should not assume U.S. law is the sole reason cannabis hasn’t emerged as a definitive treatment option.”

Wurster emphasized that these changes bring new responsibilities for the medical community, as smoked and inhaled products may not be safe for all individuals.

“We still need to comprehend the best methods for delivering appropriate medications and guidance to the right patients,” she cautioned. “Available products are frequently unregulated and present significant mental health risks, particularly among young users, as well as cardiovascular concerns, necessitating greater caution.”

A Major Shift in Cannabis Policy After 55 Years

The regulatory barriers that researchers face have roots extending back over fifty years. Under the Nixon administration, the Controlled Substances Act of 1970 categorized marijuana as a Schedule I drug.

Almost six decades later, much regarding marijuana’s medicinal potential remains undiscovered. Currently, from a legal standpoint, it is viewed merely as a substance of abuse, Wurster noted.

Susan Ferguson, director of the Institute on Addiction, Drugs and Alcohol at the University of Washington School of Medicine, anticipates that obtaining cannabis research licenses will soon become easier for scientists. Presently, researchers can broadly license drugs classified from Schedule II to V, while those exploring Schedule I substances must secure individual licenses for each.

“This necessitates a detailed written protocol,” she explained. “It involves DEA personnel visiting to review research and experimental strategies, which complicates the process considerably.”

Ferguson believes that reclassifying marijuana would “open the floodgates” for clinical research. Participants may be more willing to engage in Schedule III studies than in those involving Schedule I drugs.

Ferguson compared cannabis to alcohol and tobacco, which, although common, are not benign. Due to medical research, their risks are well documented.

“We have yet to conduct that level of research on cannabis,” Ferguson concluded. “Ultimately, we aim to inform people more comprehensively about the risks and benefits associated with its use.”