46% of cannabis users reported replacing their prescription medications — mostly opioids, anxiety meds, and antidepressants

The Survey

Corroon's team recruited participants through a mix of channels — social media, cannabis dispensary flyers in Washington State, public lectures, the website of Bastyr University's research institute, and even a community website for mothers with multiple sclerosis. Between December 2013 and January 2016, 2,774 eligible respondents completed an anonymous 44-item online questionnaire about their cannabis use patterns, including whether they had ever intentionally substituted cannabis for prescription medications.

The sample was predominantly white (86%), slightly more male than female (56% vs 44%), and young — nearly half were between 22 and 35. About 60% identified as medical cannabis users; the remaining 40% called themselves recreational users. Eighty-three percent lived in the United States, with smaller groups from Europe (10%) and Canada (4%).

The single most important question was straightforward: Have you ever used cannabis as a substitute for prescription drugs?

Across all respondents who reported substituting, a total of 2,473 individual substitutions were recorded — roughly two medications per person. Opioid substitution was 2.6 times more frequent than benzodiazepine substitution, making it by far the dominant pattern.

Who Substitutes — and Who Doesn't

Not everyone in the survey was equally likely to replace their medications with cannabis. The differences revealed something important about who is driving this behavior.

Medical cannabis users were nearly five times more likely to report substituting than recreational users. But the most striking finding was the gender gap: female medical users were six times more likely to substitute than female recreational users — a stronger effect than seen in men. Women managing chronic conditions with cannabis appear to be especially motivated to reduce their pharmaceutical burden.

People managing the triad of pain, anxiety, and depression simultaneously were 1.66 times more likely to substitute (95% CI 1.27-2.16). This matters because it's precisely the patient population most likely to be on multiple prescription medications — opioids for pain, benzodiazepines for anxiety, SSRIs for depression — and most vulnerable to polypharmacy side effects and drug interactions.

The Surprising Finding: Legal Status Doesn't Matter

If cannabis substitution were driven primarily by access and legal protection, you'd expect higher substitution rates in states with medical cannabis laws. Corroon tested this directly.

This is the finding that should make both cannabis advocates and prohibitionists uncomfortable. Legalization didn't significantly increase substitution behavior — but neither did prohibition prevent it. People are making these decisions on their own, in their own homes, based on their own experience. The legal framework is largely irrelevant to the individual calculus of "does this work better for me than what my doctor prescribed?"

A Growing Body of Evidence

Corroon's 2017 survey wasn't the first to document substitution behavior, and it wasn't the last. It sits within a remarkably consistent evidence base.

The convergence is striking. Whether researchers look at population-level death rates, state-level prescribing data, dispensary surveys, or prospective clinical cohorts, the same pattern emerges: when people have access to cannabis, a substantial proportion use less of their prescription medications. The effect is especially pronounced for opioids.

But convergence is not causation. The studies all have different limitations — and Corroon's has some significant ones.

The Credibility Question

The central weakness is the one that plagues all cannabis survey research: the people who respond to surveys distributed through cannabis dispensaries and social media are overwhelmingly people who like cannabis. The 54% who didn't report substituting are almost invisible in the discussion — and the unknown number of people who tried cannabis, hated it, and went back to their prescriptions aren't in the data at all.

The PROMIS Global Health scores reveal this bias. The sample scored about one standard deviation below the general population on both mental health (T-score 39.34, population mean 50) and physical health (T-score 40.26). These are people who are sick, actively managing their health, and already engaged with cannabis — not a random cross-section of Americans.

But here's the thing: that doesn't make the finding wrong. It makes it specific. Among people who use cannabis and are willing to tell you about it, nearly half are replacing prescription drugs. That's a real behavior happening at real scale, and the healthcare system needs to know about it — even if the precise percentage would be different in the general population.

What This Means for Patients

If you're considering using cannabis to replace a prescription medication, this study tells you that you wouldn't be alone — but it doesn't tell you that it's a good idea for your specific situation.

The medications most commonly substituted — opioids, benzodiazepines, and antidepressants — all have significant withdrawal risks. Stopping opioids abruptly can cause severe withdrawal syndrome. Stopping benzodiazepines abruptly can cause seizures. Stopping SSRIs abruptly can cause discontinuation syndrome. Cannabis doesn't prevent any of these withdrawal effects.

What the study does suggest is that cannabis may function as a harm reduction tool — not necessarily by being a better medicine than what it replaces, but by being a good-enough alternative with a less dangerous side effect profile. Corroon himself has emphasized that this process should involve medical supervision, noting that CBD can inhibit cytochrome P450 enzymes and amplify the effects of drugs like benzodiazepines, creating dangerous interactions if not managed carefully.

The finding that almost a quarter of even recreational users report substitution is particularly concerning from a safety perspective. These are people making unmonitored medication changes without the framework of a medical cannabis recommendation, let alone physician oversight.

What the researchers found

Of 2,774 cannabis users surveyed, 1,248 (46%) reported using cannabis as a substitute for prescription drugs. The most commonly replaced drug classes were opioids/narcotics (35.8%), anxiolytics/benzodiazepines (13.6%), and antidepressants (12.7%). A total of 2,473 substitutions were reported — approximately two medications per person who substituted. Medical cannabis users were 4.59 times more likely to substitute (95% CI 3.87-5.43). Female medical users showed the strongest signal at OR 6.09 (95% CI 4.65-7.80). State legal status had no significant effect on substitution behavior (47% vs 45%, p=0.58).

Why it matters

This study quantified a phenomenon that healthcare systems were largely ignoring: widespread, patient-driven substitution of cannabis for prescription medications. The finding that nearly half of cannabis users replace prescription drugs — particularly opioids during the peak of the opioid epidemic — has implications for harm reduction, clinical practice, and drug policy. The legal status finding is equally important: substitution happens regardless of the law, suggesting healthcare systems need to engage with this behavior rather than pretend it depends on policy.

The numbers in context

2,774 cannabis users surveyed. 1,248 (46%) substituted. Substituted drugs: opioids 35.8%, benzodiazepines 13.6%, antidepressants 12.7%. 2,473 total substitutions (~2 per person). Medical users: 4.59x more likely to substitute. Pain/anxiety/depression: 1.66x more likely.

How the study worked

Anonymous online 44-item questionnaire using REDCap, with PROMIS Global Health 10-item short form. Self-selected convenience sample of 2,774 cannabis users who had used at least once in the past 90 days. Recruited through social media, cannabis dispensary flyers in Washington State, Bastyr University website, public lectures, and online cannabis magazine. Data collected December 2013 to January 2016. Bastyr University IRB approved.

What this study cannot tell us

Self-selected convenience sample recruited through cannabis-friendly channels, likely overrepresenting cannabis enthusiasts. Self-reported substitution with no clinical verification of medication changes or outcomes. Open-ended drug names created coding challenges. Some substituted drugs may have been OTC rather than prescription. PROMIS health scores show the sample was significantly less healthy than the general population. Timeline mismatch between data collection period (2013-2016) and legal status analysis date (2016). No information on whether substitution was medically supervised.

How to read the evidence

Large survey providing important descriptive data on real-world behavior, but self-selected convenience sample with no clinical outcome data. Captures what patients do, not whether it improves their health.

When this study was published

Published in 2017 with data collected 2013-2016. The substitution pattern has been replicated in multiple subsequent studies through 2021, including prospective data.

The bigger picture

Corroon's study is part of a convergent evidence base — from population-level mortality data (Bachhuber 2014) to prescribing records (Bradford 2016) to dispensary surveys (Boehnke 2016) to prospective cohorts (Lucas 2021) — all pointing in the same direction: when people have access to cannabis, many reduce their use of prescription medications. The question is no longer whether this happens, but whether it leads to better or worse health outcomes.

Questions still open

• Do patients who substitute cannabis for opioids experience better or worse pain outcomes? Is substitution happening with physician knowledge, or are patients making unilateral medication changes? Does unsupervised substitution lead to undertreated conditions or dangerous withdrawal? Would the substitution rate differ in a representative sample rather than a cannabis-using convenience sample?

Common questions

Read the original research

Cannabis as a substitute for prescription drugs - a cross-sectional study.

Journal of pain research, 10, 989-998

Citation

Corroon, James M; Mischley, Laurie K; Sexton, Michelle. (2017). Cannabis as a substitute for prescription drugs - a cross-sectional study.. Journal of pain research, 10, 989-998. https://doi.org/10.2147/JPR.S134330

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