Over 10 million people in Japan suffer from migraines, and for many, traditional preventive medications simply didn't work. Now a monthly injection that can cut migraine attacks in half is changing lives, and 94% of patients say they're satisfied. Here's how Japan's latest research is reshaping migraine treatment.

Migraine: Far More Than "Just a Headache"

Migraine affects more than one billion people worldwide and ranks as the second-most burdensome neurological disorder after stroke. In Japan, the prevalence stands at 8.4%, disproportionately affecting women aged 20–40: while 3.6% of men experience migraines, the rate among women is 12.9%, more than three times higher.

The hallmark throbbing pain of a migraine attack can persist for 4 to 72 hours and is frequently accompanied by sensitivity to light and sound, nausea, and vomiting. About one in four patients also experience "aura" before an attack, visual disturbances such as shimmering zigzag lines spreading across the visual field, a phenomenon known in Japanese as senki-anten (閃輝暗点).

What makes migraine particularly devastating is its impact beyond pain itself. Sufferers are forced to miss work or school, and their productivity plummets during attacks. The constant anxiety of not knowing when the next episode will strike makes planning daily life difficult. Migraine is recognized as one of the leading causes of productivity loss among people under 50, carrying immense social and economic costs.

The CGRP Discovery That Changed Everything

For decades, the mechanism behind migraines remained a mystery. Recent research has pointed to the "trigeminovascular theory" as the leading explanation. The trigeminal nerve, which extends across the membrane covering the brain, releases a substance called CGRP (Calcitonin Gene-Related Peptide) from its terminals. CGRP acts on blood vessels surrounding the brain, causing them to rapidly dilate and triggering inflammatory responses, producing that characteristic throbbing pain.

Understanding this mechanism sparked a revolution in migraine treatment. In 2021, antibody drugs that directly target CGRP or its receptor became available in Japan.

Three types of CGRP-related antibody drugs are currently approved in the country. Galcanezumab (brand name: Emgality) and fremanezumab (brand name: Ajovy) are "anti-CGRP antibodies" that neutralize the CGRP molecule itself. Erenumab (brand name: Aimovig) takes a different approach, it's an "anti-CGRP receptor antibody" that blocks the receptor, preventing CGRP from binding to it.

Think of it as a lock-and-key system. CGRP is the "key" and the CGRP receptor is the "lock." When the key enters the lock, the migraine "door" opens. CGRP antibody drugs work by either destroying the key or blocking the lock, ensuring the door never opens in the first place.

These drugs are administered as subcutaneous injections, typically once a month, with some formulations allowing quarterly dosing. Compared to traditional oral preventive medications (such as valproate or propranolol), they offer stronger efficacy with fewer side effects.

Keio University's Study Proves Real-World Effectiveness

A research team led by Dr. Tsubasa Takizawa, a senior lecturer at Keio University School of Medicine, analyzed data from 150 migraine patients who began CGRP antibody treatment at Keio University Hospital between August 2021 and February 2023. The study included patients with both episodic migraine (attacks occurring several times per month) and chronic migraine (headaches on 15 or more days per month), evaluating long-term efficacy, safety, and patient satisfaction.

The results were striking.

Among patients who continued treatment, monthly migraine days steadily declined after the start of therapy. At six months, 54% of patients had their migraine frequency reduced by half or more. At one year, 52% maintained this level of improvement. In practical terms, someone who previously suffered ten migraine days per month would now experience five or fewer.

Importantly, the benefits extended beyond headache frequency. Improvements were observed in aura symptoms, sensitivity to light and sound, and accompanying nausea and vomiting.

Side effects were relatively mild. Injection site reactions (such as pain or redness) were observed in 25% of patients at six months, declining to 11% at one year. Serious adverse events were rare.

The most remarkable finding, however, was patient satisfaction. At six months, 92% of patients reported being satisfied with treatment. At one year, that figure rose to 94%. For people who had struggled with migraines for years, often without adequate relief, these numbers speak volumes about how profoundly this treatment can improve quality of life.

The study was published on January 15, 2026, in the Journal of the Neurological Sciences.

Cost and Access in Japan

CGRP antibody drugs are covered by Japan's national health insurance system. Under the standard 30% copayment, patients pay approximately $80–90 per injection, with insurance covering the remaining 70%.

However, access comes with conditions. Japanese Headache Society guidelines require that patients experience at least four migraine days per month and have failed at least one conventional preventive medication before being eligible for CGRP therapy. Additionally, only medical facilities with physicians who have five or more years of headache treatment experience can prescribe these drugs.

This approach contrasts with guidelines in Europe and the United States, where CGRP antibody drugs are increasingly positioned as first-line preventive treatments. Some in Japan advocate for earlier access, arguing that patients shouldn't have to endure months of inadequate treatment before qualifying.

For comparison, South Korea also has CGRP antibody drugs available but enforces even stricter criteria, requiring failure of three or more preventive medications. Insurance covers only an estimated 5–15% of migraine patients, highlighting a significant access gap.

The Future of Migraine Treatment Keeps Expanding

Building on the success of CGRP antibody injections, the migraine treatment landscape continues to evolve rapidly.

In September 2025, Pfizer's oral CGRP receptor antagonist rimegepant (brand name: Nurtec in many markets) was approved in Japan under the brand name Nurtec OD. This marked a historic first in Japan, an oral medication effective for both acute migraine treatment and prevention. For patients who dislike injections, this represents a significant new option.

Additionally, AbbVie's oral CGRP receptor antagonist atogepant, submitted for approval in Japan in March 2025 for migraine prevention, received approval in February 2026 under the brand name Aquipta, adding another once-daily pill-based preventive option.

Beyond medications, CGRP antibody intravenous formulations and neuromodulation therapies, which use electrical stimulation to regulate nerve activity, are also under development.

For too long, migraine sufferers were told their condition was simply "something to live with" or "manageable with painkillers." Today, advances in science are ushering in an era where migraine attacks can be prevented before they start. The Keio University study offers compelling real-world evidence that these treatments deliver on their promise, bringing hope to millions of migraine patients in Japan and beyond.

What's the migraine treatment situation like in your country? Are CGRP-based therapies available to patients? We'd love to hear about your country's approach to tackling migraines.

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