Medical Cannabis for Migraines in the UK: Evidence and Access

Introduction

Migraine is one of the most prevalent and debilitating neurological conditions in the world, affecting an estimated 10 million people in the UK. It is the second leading cause of disability globally, according to the Global Burden of Disease study. Despite this, a significant proportion of migraine patients — particularly those with chronic migraine (15 or more headache days per month) — do not achieve adequate relief from conventional preventive and acute treatments.

Since 2018, medical cannabis has been legally prescribable in the UK for conditions where conventional treatments have failed. A growing body of evidence suggests that cannabinoids may have a role in migraine management, both as a preventive treatment and for acute relief. This guide explains the evidence, who may be eligible, and how to access a prescription.

The Evidence for Cannabis and Migraine

The evidence base for medical cannabis in migraine has grown substantially in recent years. Key findings include:

• A 2019 study published in the Journal of Pain found that inhaled cannabis reduced migraine severity by 47.3% on average, with a reduction in migraine frequency from 10.4 to 4.6 headaches per month.

• A 2020 retrospective study found that medical cannabis use was associated with a significant reduction in migraine and headache frequency, with 39.7% of patients reporting a greater than 50% reduction in headache days.

• Data from the UK Medical Cannabis Registry shows that patients prescribed CBMPs for headache disorders reported significant improvements in pain scores and quality of life at three and six months.

The proposed mechanisms are multiple. The endocannabinoid system is involved in pain modulation, neuroinflammation, and serotonin signalling — all of which are implicated in migraine pathophysiology. Cannabinoids may reduce the release of calcitonin gene-related peptide (CGRP), a key mediator of migraine pain, and may modulate the trigeminovascular system that is central to migraine generation.

Who May Be Eligible?

Medical cannabis for migraine is typically considered in the UK when:

• The patient has a confirmed migraine diagnosis (episodic or chronic)

• At least two preventive treatments (such as topiramate, amitriptyline, propranolol, or CGRP monoclonal antibodies) have been tried and have either failed or caused intolerable side effects

• Acute treatments (triptans, NSAIDs) are providing inadequate relief or are overused

Patients with chronic migraine (15+ headache days per month) are generally more likely to be considered eligible than those with episodic migraine.

What Products Are Typically Prescribed?

For migraine, UK clinicians may prescribe:

• CBD-dominant oils — for preventive use, taken daily to reduce migraine frequency

• Balanced THC:CBD products — for patients where sleep disturbance and anxiety are contributing to migraine frequency

• THC-dominant products for acute use — for relief during a migraine attack, typically via vaporisation for rapid onset

How to Access a Prescription

CPGUK can provide free, confidential guidance on whether medical cannabis may be appropriate for your migraines and how to access a specialist consultation. The process involves an initial consultation with a specialist clinician, an eligibility assessment, and — if approved — a prescription dispensed by a licensed pharmacy.

Important Considerations

• Medication overuse headache — patients who are already overusing acute migraine medications should discuss this with the prescribing clinician, as cannabis use could potentially contribute to medication overuse headache if used too frequently for acute relief

• THC and driving — driving after consuming THC-containing products is illegal in the UK

• Cost — private medical cannabis prescriptions typically range from £150 to £350 per month

Conclusion

Medical cannabis represents a promising option for UK migraine patients who have not found adequate relief from conventional preventive and acute treatments. The evidence base is growing, prescribing is legal and accessible, and patient-reported outcomes are broadly positive. CPGUK is here to help you understand your options.