Can Medical Cannabis Help Reduce Opioid Use?: Lessons from the U.S.

Researchers from the University of Georgia and the University of Colorado examined opioid prescription patterns for 15-20 million Americans from 2007 to 2020.

Published in the American Journal of Health Economics, their comparative analysis of states with and without medical cannabis laws offers one of the most robust evaluations yet of how regulatory frameworks affect patient safety and risk reduction.

The results are striking:

• Average 16% reduction in opioid prescriptions: States that legalised medical cannabis recorded a 16% reduction in the number of patients receiving opioid prescriptions compared to previous levels. In some cases, such as Minnesota and New York, the decline was even more pronounced, exceeding 20%.
• Decrease in the amount prescribed: Not only did the number of patients receiving opioids decline, but also the number of prescriptions per patient and the total daily amount prescribed.
• Shift toward safer alternatives: Following the introduction of medical cannabis programmes, researchers observed an increase in the use of non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen and naproxen. This suggests that patients and doctors are more inclined to choose less addictive alternatives when therapeutic cannabis becomes legally available - often combining cannabis treatments with milder, safer medications.
• Broad reductions across patient populations: The decline was consistent among men and women of varying ages and racial backgrounds, with the most significant reductions seen among cancer patients and Black non-cancer patients - with both groups experiencing decreases of more than 20%.

Overall, the study concludes that providing safe and legal access to medical cannabis is associated with a significant reduction in opioid prescriptions - and may represent an effective tool in efforts to mitigate the ongoing opioid crisis.

Opioid Use in Spain

Although Spain's situation differs significantly from that of the United States, certain warning signs are emerging. The EDADES 2024 Report, published by the Spanish Observatory on Drugs and Addictions (OEDA), examined drug use among people aged 15 to 64.

Its infographic on opioid analgesics highlights the following findings:

• Consumer profile: Regular use is most common among women between the ages of 35 and 64. Prevalence and trends: From 2018 to 2024, the use of opioid painkillers in the general population increased by one percentage point. In 2024, approximately 4% of women and 3% of men reported use within the previous month, with the highest rates observed among women over 35.
• Age of onset and misuse: The average age of first use is 35.3 years. In many cases, consumption occurs outside medical recommendations, particularly with respect to dosage and treatment length.
• Addiction risk: Opioids such as morphine, oxycodone, or fentanyl carry a high risk of dependence and have already prompted public health alerts in countries like the United States.
• Additional sources reinforce these findings: A 2022 RTVE report noted that opioid use in Spain rose by nearly 54% over seven years, positioning the country as Europe's third largest consumer of fentanyl after Germany and the United Kingdom.

A 2024 article by the Spanish Society of Primary Care Pharmacists (SEFAP) reported that Spain ranks fourth among OECD countries in fentanyl consumption, with overall opioid use rising by 0.6% in the past year.

The analysis also warned that fentanyl - once marginal - now accounts for 14% of use, making it the third most common opioid after codeine and tramadol. These data suggest that, while the overall prevalence of opioid use in Spain remains relatively low, the steady rise in recent years - particularly the sharp rise in fentanyl consumption - highlights the need to develop alternative strategies for pain management.

Regulating Medical Cannabis in Spain: Potential Effects on Opioid Prescription

Practices On 7 October, 2025, the Spanish government approved Royal Decree 903/2025, establishing the first national framework for medical cannabis. The decree introduces a narrowly defined framework limited to standardized pharmaceutical formulations.

Key points:

• Hospital use only: Cannabis-based magistral formulations may be prepared and dispensed exclusively by the pharmacy departments of authorised hospitals.
• Limited indications: The decree authorises medical cannabis only when conventional treatments have proven ineffective. Approved uses include certain types of chronic pain, spasticity associated with multiple sclerosis, and chemotherapy-induced nausea.

Despite these restrictions, evidence from North America suggests that legal access to cannabis-based medicines could help reduce reliance on opioids for pain management - and, in turn, lower the risks of dependence and misuse.

The substitution effect observed in the U.S., where patients turn to cannabis for pain relief and reduce their opioid intake, could also occur in Spain, even if only to a limited extent.

An Alternative for Chronic Pain Management

Medical cannabis can provide relief for neuropathic or chronic pain conditions, where opioids often show limited efficacy and a high risk of dependence. Access to controlled THC and CBD formulations could enable specialists to reduce reliance on high‑potency opioids.

In addition, cannabis-based treatments may reduce adverse effects, given that cannabinoid formulations typically exhibit a more favourable safety and dependency profile compared with opioids.

However, Spain's approach has its own particularities: access is restricted to hospital use, with no provision for community pharmacy sales or home cultivation. Therefore, its impact on medical practice will likely be more limited than in the United States.

Even so, the decree marks an important first step in integrating medical cannabis into clinical practice - and provides an opportunity to investigate its potential role in reducing opioid use in Spain.

The U.S. experience demonstrates that medical cannabis legalisation is linked to a significant reduction in opioid prescriptions - both in the number of patients receiving them and in the doses prescribed. In Spain, however, available data reveal a steady increase in opioid use among adults, with a particularly sharp rise in fentanyl use over the past decade.

The recent regulation of medical cannabis in Spain could provide a way to reduce dependence on opioids in pain treatment. By joining the growing group of European countries that have regulated medical cannabis, Spain opens the door for patients to benefit from international experience and to address an emerging public health challenge.