How much pain relief can you realistically expect?
The honest answer is: modest relief, not a cure. A major 2022 review of 18 randomized trials (1,740 participants) found that synthetic cannabis products with high THC (over 98% THC) may produce a moderate improvement in pain severity and a 30% or greater reduction in pain for some people [1]. But the same review found that balanced THC:CBD sprays (like nabiximols) probably only give a small improvement in pain and function [1]. Another 2025 review of the broader literature puts the average pain reduction at about 0.4 to 0.7 points on a 0–10 scale [6] — a change that many patients would describe as noticeable but not life-changing. For context, a 1-point drop is often considered the minimum that patients can feel as meaningful. So while some people do get real relief, it is not a powerful or consistent effect across the board.
Can medical cannabis help you cut down on opioids?
The evidence here is mixed but promising for some. A large 2026 cohort study of 204 adults in New York State found that over 18 months, people who used medical cannabis reduced their daily opioid dose by about 3.5 morphine milligram equivalents (MME) per day for each month they had a full 30-day supply of cannabis [2]. That is a small but statistically significant reduction. However, a 2021 systematic review of randomized trials found that when patients were told to keep their opioid dose steady, adding cannabis did not lead to any meaningful opioid reduction (only about 3.4 MME less, which was not statistically significant) [4]. The same review noted that observational studies (where people chose their own doses) showed a much larger reduction of about 22.5 MME per day, but those results are considered very low certainty because people who choose to use cannabis may also be more motivated to reduce opioids [4]. So the bottom line: medical cannabis may help some people lower their opioid use, especially in real-world settings, but the effect is small and the evidence is not strong enough to guarantee it.
What are the downsides and risks?
Side effects are common and can be significant. The 2022 review found that high-THC products increase the risk of sedation and dizziness — for example, sublingual sprays with balanced THC:CBD probably cause a large increase in dizziness and sedation, and a moderate increase in nausea [1]. A 2025 review adds that common side effects include dry mouth, diarrhea, constipation, and euphoria, and that about 29% of users may develop cannabis use disorder (addiction) according to DSM-V criteria [6]. Withdrawal symptoms are also real: a 2021 study of 527 medical cannabis users with chronic pain found that 25% experienced severe withdrawal symptoms, and these symptoms tended to be stable over two years [3]. Younger age was a risk factor for worse withdrawal [3]. There are also absolute contraindications: unstable heart disease, psychotic symptoms, bipolar disorder, and pregnancy or breastfeeding [6]. So while cannabis is not as dangerous as opioids in terms of overdose risk, it is not a harmless substance either.
About These Sources
This answer is built on 6 peer-reviewed studies — published from 2021 to 2026, 2 from 2024 or later, 2 in Q1 journals, collectively cited 139 times — selected as the most relevant from 9 studies that passed quality screening, drawn from 68 papers retrieved from a database of over 500 million.
Sources used in this answer
Cannabis-Based Products for Chronic Pain
In a systematic review of 18 RCTs (n=1,740) and 7 cohort studies (n=13,095), synthetic high-THC products and balanced THC:CBD sprays showed modest short-term pain improvements but increased risks of dizziness, sedation, and nausea.
Medical Cannabis and Opioid Receipt Among Adults With Chronic Pain.
In a cohort study of 204 adults with chronic pain in New York State, each month of medical cannabis use was associated with a small reduction in opioid dose (3.53 fewer MME per day) over 18 months.
Progression of cannabis withdrawal symptoms in people using medical cannabis for chronic pain
Among 527 adults using medical cannabis for chronic pain, withdrawal symptoms were common (25% severe) and stable over 2 years; younger age predicted worse withdrawal.
Opioid-sparing effects of medical cannabis or cannabinoids for chronic pain: a systematic review and meta-analysis of randomised and observational studies.
A systematic review of 5 RCTs and 12 observational studies found very low certainty evidence that adding cannabis reduces opioid use; RCTs showed no significant opioid reduction, while observational studies showed a larger reduction (22.5 MME/day).
Comparing the effects of medical cannabis for chronic pain patients with and without co-morbid anxiety: A cohort study.
In a prospective cohort of 1,254 chronic pain patients, cannabis-based medicinal products improved pain and quality of life at 1, 3, and 6 months; those with co-morbid anxiety had greater improvements in quality of life.
Medical cannabis for chronic pain management: questions and answers between clinical and medico-legal issues.
A 2025 review reports that medical cannabis reduces pain by 0.4–0.7 on a 0–10 scale, with rare serious adverse events but common side effects (dizziness, drowsiness, nausea); risk of cannabis use disorder is about 29%.