Last verified: March 2026

What Changed

The December 12, 2024 amendment to the Cannabis Control Act included a provision allowing cannabis-derived substances to be developed as medicines through Japan's existing pharmaceutical regulatory framework. Specifically:

• Licensed pharmaceutical companies can apply to research, develop, and conduct clinical trials on cannabis-derived medicines
• The Pharmaceuticals and Medical Devices Agency (PMDA) can review and approve cannabis-based drugs through the standard new drug application process
• Approved cannabis-derived medicines can be prescribed by physicians and dispensed through licensed pharmacies
• THC-containing medicines are permitted under the pharmaceutical pathway, provided they receive full PMDA approval

This represents a genuine reversal of Japan's longstanding position that cannabis has no medical value. For decades, Japan's official stance was that cannabis was simply a dangerous drug with no therapeutic application.

What Has NOT Changed

It is critical to understand what the reform did not do:

Clinical Trials: Epidiolex

The most advanced cannabis-derived medicine in Japan's approval pipeline is Epidiolex (cannabidiol oral solution), manufactured by Jazz Pharmaceuticals (formerly GW Pharmaceuticals). Epidiolex is already approved in the United States, the EU, and several other countries for the treatment of severe epilepsy syndromes.

Timeline in Japan

• April 2024: The MHLW granted Epidiolex orphan drug designation for the treatment of Dravet syndrome and Lennox-Gastaut syndrome. Orphan drug designation provides regulatory incentives including expedited review, reduced fees, and potential market exclusivity.
• 2024-2025: Phase 3 clinical trials are underway in Japan. These trials are required even though Epidiolex has extensive clinical data from international trials, because Japan typically requires domestic clinical evidence.
• Expected approval: If trials proceed smoothly, Epidiolex could receive PMDA approval within 2-3 years. However, regulatory timelines in Japan are notoriously unpredictable.

Epidiolex (cannabidiol) was designated as an orphan drug by the Ministry of Health, Labour and Welfare in April 2024 for the treatment of seizures associated with Dravet syndrome and Lennox-Gastaut syndrome.

MHLW Orphan Drug Designation Notice, April 2024

Why Epidiolex Matters

While Epidiolex contains CBD (not THC) and treats a relatively rare condition, its significance extends far beyond epilepsy. If approved, it would be the first cannabis-derived pharmaceutical ever legally available in Japan, potentially opening the door for future cannabis-based medicines addressing a wider range of conditions.

Patient Story: Karen Miyabe

The push for medical cannabis in Japan has been driven in part by courageous patient advocates. Karen Miyabe, who suffered from severe epilepsy, became one of Japan's most visible advocates for cannabis-based medicine after experiencing dramatic improvement with cannabidiol treatment obtained outside Japan.

Miyabe's case highlighted the cruel paradox of Japanese law: a medicine legally prescribed in dozens of countries that could transform her quality of life was classified as a dangerous drug in Japan. Her advocacy helped shift public opinion and gave Japanese lawmakers a human face for the medical cannabis debate.

Patient advocates like Miyabe, alongside organizations such as Green Zone Japan, have been instrumental in achieving the 2024 reform. While the pharmaceutical pathway falls far short of what advocates hoped for, it represents progress that seemed impossible just a decade ago.

Looking Ahead

Japan's medical cannabis framework is in its earliest stages. Several factors will determine how quickly — or slowly — it develops:

• Epidiolex approval: A successful approval would validate the pathway and encourage other pharmaceutical companies to pursue cannabis-derived medicines in Japan.
• Political will: Japan's conservative political establishment remains deeply skeptical of cannabis. Expansion beyond narrow pharmaceutical use is unlikely in the near term.
• Public opinion: While younger Japanese increasingly support medical cannabis (60%+ in some surveys), broader public support remains limited. Cultural attitudes toward drugs continue to be a powerful barrier.
• International pressure: As more countries adopt medical cannabis, Japan may face increasing pressure from the international medical community to expand patient access.