💊 Over 10 million people in Japan suffer from migraines. 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 (闪輝暗点).
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 was submitted for manufacturing approval in Japan in March 2025, potentially adding another pill-based preventive option to the arsenal.
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.
References
- https://www.keio.ac.jp/ja/press-releases/2026/1/29/28-172358/
- https://www.sciencedirect.com/science/article/pii/S0022510X26000328
- https://www.jhsnet.net/guideline_CGRP.html
- https://www.pfizer.co.jp/pfizer/company/press/2025/2025-09-19
- https://www.abbvie.co.jp/content/dam/abbvie-com2/japan/documents/press-release/2025_0314.pdf
Reactions in Japan
Been on CGRP antibody injections for six months. My migraines went from 10 days a month to 2-3. No exaggeration—it changed my life. Just not waking up dreading another headache day makes me tear up.
The 90% satisfaction rate makes total sense as a migraine sufferer. After years of being told 'it's just in your head' or 'it's probably just tension,' the relief of finally having an effective treatment is indescribable.
The problem is the ongoing cost of about ¥12,000 ($80-90) every month. I know it works, but spending nearly ¥150,000 a year on migraine prevention is honestly tough. I wish the drug price would come down.
I'm a neurologist. CGRP antibody drugs are indeed groundbreaking, but media should emphasize more that they don't work for everyone. How to treat the other 50% of patients is the next challenge.
My husband's migraines used to ruin our weekends, but since starting the injections, we can go out as a family again. It doesn't just improve the patient's quality of life—it improves the whole family's.
Some people go Emgality → no effect → switch to Ajovy → dramatic improvement. Having three options is really valuable. Compatibility varies from person to person.
As someone who had to quit my job because of migraines, this feels bittersweet. If this drug had existed ten years ago, my life could have been so different. That thought is hard to shake.
Got my second CGRP shot—the injection itself is just a slight sting. Totally bearable if it means fewer migraines. Being able to self-inject at home is also a huge plus.
It's frustrating that you have to try existing preventive drugs first to qualify for insurance coverage. In the West it's a first-line treatment—why does Japan make patients take the long way around?
I'm a guy with migraines. It's often seen as a 'women's condition,' so having solid research data like this might make it easier for male patients to seek treatment too.
Rimegepant getting approved is also big news. For those who hate injections, having more oral options is genuinely exciting. A drug that works for both prevention AND acute treatment? That's a game-changer.
Migraine-related economic losses are said to be hundreds of billions of yen annually, yet public understanding is still lacking. Too many workplaces treat 'it's just a headache, don't take the day off' as normal.
From a pharmacist's perspective, it's reassuring that long-term safety data for CGRP antibody drugs is accumulating. It's only been about 5 years, but no serious issues have been reported so far.
I was honestly exhausted from just surviving each attack with triptans. The mental relief of actual prevention is incredible. So glad I went to a headache clinic.
I live in a rural area and there are only a few facilities in my prefecture that can prescribe CGRP antibody drugs. Having the medication means nothing if you can't access it. Please address this regional disparity.
I've been on Ajovy in the US for two years. Monthly out-of-pocket costs vary wildly by insurance plan—mine is $30 copay, but without insurance it's over $600/month. Japan's $80-90 copay seems quite reasonable.
India has an estimated 150 million migraine sufferers, yet CGRP antibody drugs aren't approved here yet. I hope Japan's real-world data like this contributes to faster approval in India.
In Sweden these are prescribed through public healthcare, but you need to meet strict criteria regarding migraine frequency and treatment history. The 52% response rate is encouraging, but finding solutions for the other half matters too.
Emgality is available in Brazil but not through public healthcare. At around 800 reais (~$150) per month, it's unrealistic for most people. The treatment gap between developed and developing countries is just too wide.
I'm three months into CGRP therapy in the UAE. Migraines are often dismissed as 'not serious' in the Middle East, especially when women report them—it gets brushed off as 'just stress.' I hope studies like this help shift medical professionals' attitudes too.
I'm a migraine patient in Korea. I'm envious that Japan covers these drugs after just one preventive failure. In Korea you need three or more failures, and so many patients suffer throughout that process. We need insurance reform.
German neurologist here. The 94% satisfaction rate aligns with our clinical experience. However, as an observational study of patients who continued treatment, we should also consider dropout data for a complete picture.
France has had CGRP antibody drugs since 2019, but wait times are the real problem. Neurology appointments take 3-6 months, and you just endure attacks in the meantime. Having the drug available doesn't solve everything.
CGRP antibody drugs are available on the NHS in the UK, but NICE guidelines require failure of at least three preventive treatments for chronic migraine. Surprised that Japan actually has easier access than us.
In Mexico there's almost no social understanding of migraines, and accessing treatment itself is difficult. CGRP antibody drugs are only available at some private hospitals, and most patients rely on over-the-counter painkillers.
I'm Japanese living in the US, currently on Aimovig. I needed prior authorization before insurance kicked in, and it took two months to get approved. Japan's clear insurance coverage framework is something I envy.
I'm a GP in Ireland. Migraine is an 'invisible disability' and patients' suffering is routinely underestimated. It's great that the Japanese study measured satisfaction—treatment outcomes can't be captured by numbers alone.
In Poland, the concept of migraine preventive treatment isn't widely understood yet. Many patients cycle through 'take a painkiller when it hurts,' leading to medication overuse headache. Raising awareness about prevention is urgent.
In Australia, CGRP antibody drugs have been covered under the PBS since 2020, but only for chronic migraine with 15+ headache days per month. Having 10 days of severe migraines and still not qualifying doesn't sit right.
Taiwan recently gained access to CGRP antibody drugs, but insurance criteria are very strict. The Keio study is extremely valuable as Asian real-world evidence. Data from Western populations alone isn't sufficient.