Decoding Cannabis: what the first placebo-controlled cannabis migraine trial means for patients in 2026
8 min read
Sam North
In late 2024, researchers from the University of California, San Diego conducted the first ever randomised, placebo-controlled trial of vaporised cannabis flower for acute migraine treatment. Of the four medical cannabis options tested, a balanced combination of 6% THC and 11% CBD flower delivered pain relief to 67.2% of patients at 2 hours, compared to 46.6% with placebo. ‘Pain freedom’ at 2 hours more than doubled with this combination, and the benefits held at both 24 and 48 hours.
For more than 130 years, since Sir William Osler (one of the four founding professors of Johns Hopkins Hospital) described cannabis as “probably the most satisfactory remedy for migraines” all the way back in 1892, debate has raged. But with the release of the results from this trial (with more trails planned in the coming years), along with the ever-growing base of patient reported data, the conversation is shifting from anecdotal to evidential.
In today's edition of Decoding Cannabis, we pick apart what the trial actually tested, what it found, and how those results compare to what UK patients prescribed medical cannabis treatment for migraines recently reported in the largest survey of active UK medical cannabis patients ever conducted.
Contents
What did the first cannabis migraine trial actually test?
More than 1 billion people globally are affected by migraines each year. It is the second leading cause of ‘years lived with disability’ worldwide (and the main cause in women aged 15 to 49 years), which only goes to show just how crucial it is for effective treatment options to be developed, tested, proven, and offered to patients.
Yet acute treatment options, ones that offer pain relief without heavy side effects, remain frustratingly limited. A more than meaningful proportion of patients report discontinuing pharmaceutical treatment due to finding inadequate relief from standard treatment options.
And this is precisely what makes the trial in question (along with the patient reported data from the 2025 UK medical cannabis survey) so significant, and exciting.
Randomised, double-blind, placebo controlled, and using a cross-over design. Truly the ‘gold-standard’ of clinical research methodology, and exactly the kind of rigour that cannabis as a medicine needs to be accepted as a legitimate treatment option.
So, what was actually tested?
The 92 enrolled participants were treated for up to four separate migraine attacks, each time with a different treatment option, with a total of 247 migraine attack being treated across the study. For an attack to be included in the study, there needed to be a minimum of one week break between attacks, to ensure that any residual effects from previous treatments time to fully clear the patients' system. Outcomes were recorded at four different times across the next two day at the 1, 2, 24, and 48 hour mark).
The four cannabis treatment options tested
|
Treatment |
THC content |
CBD content |
Notes |
|
THC-dominant |
~6% |
<0.05% |
Below typical recreational potency |
|
CBD-dominant |
<0.5% |
~11% |
Non-intoxicating |
|
THC + CBD combination |
~6% |
~11% |
Balanced ratio |
|
Placebo |
<0.025% |
0.14% |
Cannabinoids chemically extracted |
What did the cannabis for migraine trial results show?
The findings were what can only be described as very clear. The THC + CBD combination option outperformed all other options across almost all metrics. That’s not all, though. Both the THC-dominant and the CBD-dominant option offered better pain relief, pain freedom, and ‘most bothersome symptom’ freedom than the placebo.
Pain relief at the 2-hour mark hit 67.2% with the THC + CBD combination, compared to 46/% with the placebo. Pain freedom, or the complete absence of pain, reached 34.5% with the combo cannabinoid option, compared to the placebo’s 15.5%. And the ‘most bothersome symptom’ freedom (which could refer to nausea, heavy light sensitivity, sound sensitivity, etc.) was at 60.3%, compared to 34.5% with the placebo alone.
The THC-dominant treatment option did score highest for pain relief, with 68.9%, but the THC + CBD combination option came in a very close second with 67.2%
2-hour results versus placebo
|
Outcome at 2 hours |
Placebo |
CBD only |
THC only |
THC + CBD |
|
Pain relief |
46.6% |
52.6% |
68.9% ✓ |
67.2% ✓ |
|
Pain freedom |
15.5% |
22.8% |
27.9% ✓ |
34.5% ✓ |
|
MBS freedom |
34.5% |
42.1% |
47.5% |
60.3% ✓ |
✓ = statistically significant versus placebo
Sustained relief at 24 and 48 hours across all four treatment options
|
Outcome |
Placebo |
CBD only |
THC only |
THC + CBD |
|
Sustained pain freedom (24h) |
10.7% |
16.0% |
19.6% |
28.0% ✓ |
|
Sustained pain freedom (48h) |
10.2% |
13.0% |
13.5% |
22.9% ✓ |
|
Sustained MBS freedom (24h) |
25.0% |
30.0% |
37.5% |
46.0% ✓ |
|
Sustained MBS freedom (48h) |
18.4% |
28.3% |
26.9% |
39.6% ✓ |
✓ = statistically significant versus placebo
What are the limitations of this migraine trial?
No single trial should ever be taken as gospel, and this one is no exception. There are a few limitations that should be discussed.
-
This paper has not yet been peer-reviewed.
-
It was conducted at a single treatment centre with a cohort of under 100 participants. Larger studies will need to be conducted to properly confirm these findings, but they do seem to be mirrored somewhat by the emerging anecdotal evidence (more on this in the next section).
-
The trial only looked at acute treatment within the first 48 hours. It did not assess or examine repeated, long-term medical cannabis treatment for migraine, and whether it can help reduce the frequency or severity of attacks over time.
What do UK patients have to say about medical cannabis treatment for migraines?
In November 2025, Releaf ran the largest survey of active UK medical cannabis patients ever conducted. Of the 1,669 respondents, 43 were prescribed legal medical cannabis as part of their migraine treatment plan.
The findings sit very much in line with the UC San Diego trial we have just discussed, and went a little further in terms of capturing the longer term, real-world impact that medical cannabis for migraine treatment can have on not only symptom control, but also quality of life.
With this migraine cohort of 4 patients, every single one reported that the treatment was effective to a certain degree, with 83.7% rating it very effective or extremely effective. The onset of effect pattern is worth noting in light of the trial's acute findings, with 39.5% reporting relief from the first dose, 46.5% within the first 24 hours, and 72.1% within the first week.
Quality of life improved for 97.7% of respondents, only 3 respondents reported any side effects at all, and 100% reported that they would recommend Releaf medical cannabis treatment to someone else with a qualifying condition.
Releaf UK migraine patient survey snapshot (n=43)
|
Patient-reported outcome |
Figure |
|
Treatment effective (any level) |
100% |
|
Very or extremely effective |
83.7% |
|
Relief within the first day |
46.5% |
|
Relief within the first week |
72.1% |
|
Relief within the first month |
90.7% |
|
Quality of life improved |
97.7% |
|
No side effects reported |
93.0% |
|
Would recommend to others |
100% |
The normal caveats apply to this data: It is quite a small sample group, there was no placebo, and the patients reported the results themselves, but the patterns are very promising and align quite closely with the UC San Diego trial measured under controlled conditions.
How to access medical cannabis for migraine in the UK
Simple.
Head to our cost and obligation free medical cannabis eligibility checker. It takes just 20 to 30 seconds to compete, and will give you a clear idea of your next steps As the most trusted UK medical cannabis clinic with a world-class clinical team of more than 50+ specialists covering every single qualifying condition for medical cannabis treatment in the UK, Releaf is here to help you take back control of your health.
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Further reading
Decoding Cannabis: what the first placebo-controlled cannabis migraine trial means for patients in 2026
The first randomised, placebo-controlled trial of vaporised cannabis for migraine attacks has finally been published. Researchers at UC San Diego compared THC, CBD, a balanced combination, and placebo across 247 treated migraines. The balanced ratio came out clearly ahead, with sustained benefit at 24 and 48 hours and no serious adverse events. We unpack what the trial proves, where it falls short, and how the results sit alongside Releaf's UK patient survey data on medical cannabis for migraine.
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