The New Migraine Prevention Guideline: What's Actually Changed

Migraine prevention guidance in the US has received its first comprehensive update since 2012. In the fourteen years between guidelines, an entirely new generation of migraine-specific treatments has arrived — but one of the most interesting conclusions from the new evidence review is that there still isn't one preventive medication that clearly wins.

Published on 31 August 2026 by the American Academy of Neurology (AAN) and American Headache Society (AHS), the guideline draws on a systematic review of 217 studies and sets out when prevention should be considered, which treatments have the strongest evidence, and how long they should be tried before deciding they haven't worked.

This is US guidance, not a change to NHS or NICE recommendations. But the underlying evidence is relevant well beyond America, particularly because the review incorporates both established preventive drugs and newer CGRP-targeting treatments.

TL;DR

• Preventive treatment should be offered from four migraine days per month, four moderate-to-severe headache days per month, or when migraine causes substantial disability.
• There is no clearly superior preventive medication. Choice depends on the evidence alongside tolerability, safety, cost and practical considerations such as dosing.
• CGRP-targeting treatments are now firmly incorporated into the evidence base, alongside established options such as propranolol and topiramate.
• Galcanezumab and erenumab have high-confidence evidence for episodic migraine. Fremanezumab, galcanezumab and onabotulinumtoxinA have high-confidence evidence for chronic migraine.
• Most preventives need a proper trial: generally at least 8–12 weeks at the recommended tolerated dose. OnabotulinumtoxinA is an important exception, with 24 weeks recommended before assessing efficacy.
• The guideline gives particular attention to medication overuse, pregnancy and reproductive planning, older adults and people with other health conditions.

Why This Guideline Matters

The previous comprehensive AAN guidance on pharmacological migraine prevention dates from 2012. Since then, migraine treatment has changed substantially.

For decades, prevention relied heavily on medicines originally developed for other conditions: beta blockers such as propranolol, antiseizure medicines such as topiramate and valproate, and certain antidepressants. Then came treatments targeting calcitonin gene-related peptide, or CGRP — a signalling molecule closely involved in migraine biology. CGRP monoclonal antibodies began arriving from 2018, followed by oral CGRP receptor antagonists known as gepants.

The new guideline brings those newer options into the same evidence assessment as established treatments. Its companion systematic review considered 217 studies identified through searches extending to 6 June 2024. Rather than producing a simple league table of drugs, however, the resulting guidance emphasises something more useful: choosing a preventive depends on the individual.

When Should Migraine Prevention Be Offered?

One of the clearest recommendations concerns when preventive treatment should enter the conversation. The guideline says clinicians should offer prevention to adults experiencing:

• Four or more migraine days per month
• Four or more moderate-to-severe headache days per month
• Substantial migraine-related disability

That last category matters. Someone doesn't necessarily need to reach a particular number of attacks if migraine is already significantly interfering with work, daily activities or quality of life.

The guideline also recommends that people with migraine should be told that effective preventive treatments exist for frequent attacks. That's an important distinction from treating migraine only when it happens. Acute treatments aim to stop or reduce an individual attack. Preventive treatment tries to reduce how frequently attacks occur, their severity or their impact over time.

For context, chronic migraine is defined as at least 15 headache days per month for more than three months, with migraine features on at least eight days per month.

There Still Isn't One "Best" Migraine Preventive

Perhaps the most interesting finding from 217 studies is what the evidence doesn't establish. There isn't sufficient high-quality comparative evidence to say that one preventive medication is clearly superior to all the others.

That matters because newer treatments can easily be interpreted as automatically better treatments. The guideline doesn't support such a simple hierarchy. Instead, treatment choice should take account of the strength of evidence alongside adverse effects and tolerability, longer-term safety, cost and practical considerations such as how the medication is taken and how frequently it needs to be used.

Personal circumstances matter too. A medication's other effects can sometimes be useful — someone who also has hypertension, for example, may have different considerations from someone with obesity or another condition that could be affected by a preventive's side-effect profile.

The result is less satisfying than a ranked list of the "best" migraine drugs, but considerably more useful clinically.

Where Is the Evidence Strongest?

Although there is no overall winner, the review found stronger evidence for certain treatments in particular forms of migraine.

For episodic migraine, high-confidence evidence supports galcanezumab and erenumab. Other treatments have moderate-confidence evidence, including atogepant, eptinezumab, fremanezumab, propranolol, topiramate and valproate.

For chronic migraine, high-confidence evidence supports fremanezumab, galcanezumab and onabotulinumtoxinA (Botox). Moderate-confidence evidence also supports several other options, including atogepant, eptinezumab, erenumab, topiramate and valproate.

This doesn't mean everyone with migraine should start with one of the high-confidence treatments. Evidence quality is one part of the decision rather than an automatic prescribing order.

Access matters too. For UK patients, which treatments are available through the NHS and when they can be prescribed are governed by NICE recommendations and NHS eligibility criteria, not this American guideline.

Give Preventive Treatment Enough Time

One of the most practically useful recommendations concerns something that can easily undermine treatment: deciding too quickly that it hasn't worked.

For most migraine preventives, the guideline recommends giving treatment at least 8–12 weeks at the recommended tolerated dose before assessing efficacy. The wording matters. It isn't simply 8–12 weeks from swallowing the first tablet. Some treatments require gradual dose adjustment, so reaching a dose that can reasonably test the medication may itself take time.

OnabotulinumtoxinA is different. For this treatment, the guideline recommends 24 weeks before efficacy is assessed.

Migraine prevention therefore requires a different mindset from acute treatment. A painkiller can often be judged within hours. A preventive is trying to alter the pattern of migraine over weeks or months. Stopping too early can make an effective treatment look ineffective. Equally, continuing indefinitely without properly assessing whether migraine frequency or disability has improved isn't useful either.

What If Medication Overuse Is Part of the Problem?

Frequent use of acute headache medication can itself contribute to worsening headache patterns — known as medication-overuse headache.

Importantly, the new guideline doesn't suggest that preventive treatment should simply be withheld until medication overuse has been completely resolved. Instead, prevention should still be offered where appropriate. The guideline identifies evidence of benefit in people with medication overuse for treatments including CGRP monoclonal antibodies, atogepant, onabotulinumtoxinA and topiramate.

That doesn't make these a universal preferred list. Rather, it means there is specific evidence supporting their use in this population. Medication use, headache frequency and response to prevention still need to be monitored as part of the overall treatment plan.

Pregnancy and Reproductive Planning Matter

Preventive migraine treatment becomes more complicated for anyone who could become pregnant.

The guideline gives reproductive counselling its strongest level of recommendation and emphasises discussing potential pregnancy when choosing treatment. This is particularly important for drugs with known risks during pregnancy. Valproate and topiramate require particular caution and should be avoided where possible in people who could become pregnant, with treatment decisions made with an appropriate clinician.

During pregnancy itself, medication choices narrow considerably. The guideline emphasises non-drug approaches where possible and careful consideration of the potential benefits and risks of any preventive treatment.

The broader point is simple: pregnancy shouldn't be an afterthought in choosing a migraine preventive. It can materially change which treatment is appropriate.

What This Means If You Get Migraine

The first takeaway is that four migraine days a month is enough for prevention to be a legitimate conversation. You don't need to wait until migraine has become chronic. And if attacks are substantially affecting your ability to work or function, disability itself can justify considering prevention even without reaching a particular monthly count.

Second, don't assume the newest drug must be the best one. CGRP-targeting medicines have transformed the treatment landscape and several have strong evidence behind them. But the new review doesn't establish that one medication is universally superior.

Third, give treatment a fair trial. For most preventives, that means 8–12 weeks at an appropriate tolerated dose. Migraine patterns fluctuate naturally, so judging a preventive from a handful of good or bad weeks can be misleading.

And finally, treatment should fit the person rather than simply the migraine diagnosis. Other health conditions, potential side effects, reproductive plans, cost, availability and how a medicine is taken can all change the calculation. Everyday factors matter alongside medication: sleep quality, regular movement and underlying inflammation all sit around the same picture.

Frequently Asked Questions

When should preventive migraine treatment be considered?

The new AAN/AHS guideline recommends offering prevention from four migraine days per month, four moderate-to-severe headache days per month, or when migraine causes substantial disability.

What is the best medication for preventing migraine?

There isn't one clearly established best treatment. Comparative evidence is insufficient to declare a universal winner, so treatment choice should consider evidence, tolerability, safety, cost and individual circumstances.

Which migraine preventives have the strongest evidence?

For episodic migraine, the review found high-confidence evidence for galcanezumab and erenumab. For chronic migraine, high-confidence evidence supports fremanezumab, galcanezumab and onabotulinumtoxinA.

How long should a migraine preventive take to work?

For most preventive medicines, the guideline recommends at least 8–12 weeks at the recommended tolerated dose before assessing efficacy. OnabotulinumtoxinA should generally be assessed after 24 weeks.

What is chronic migraine?

Chronic migraine means at least 15 headache days per month for more than three months, with at least eight days per month having migraine features.

Does this change migraine treatment in the UK?

No. This is guidance from US medical organisations rather than NICE. UK prescribing and NHS access continue to follow NICE guidance and relevant NHS criteria. The guideline is nevertheless significant because it draws together a large body of contemporary evidence on preventive migraine treatments.

The Bottom Line

After reviewing 217 studies, the new migraine guideline doesn't produce a single winning drug. That's arguably its most useful conclusion.

Migraine prevention should be considered earlier than some people may realise: from four migraine days a month, four moderate-to-severe headache days, or when migraine is causing substantial disability. But what happens next depends on the individual.

New CGRP-targeting medicines now sit firmly within the preventive landscape, while older treatments remain relevant. Most medications need weeks at an appropriate dose before they can fairly be judged, and factors such as side effects, other health conditions, pregnancy, cost and access can matter as much as headline efficacy.

Fourteen years after the previous comprehensive AAN guidance, migraine prevention has far more options. The new guideline's message isn't that everyone should use the newest one. It's that there are now enough effective options to make choosing the right one a genuinely individual decision.

This article is for general information and does not constitute medical advice. If migraine is frequent or affecting your daily life, speak to your GP or another qualified healthcare professional about whether preventive treatment may be appropriate.

For the daily habits that sit around all of this, The Sleep Reset covers light, timing and wind-down routines, and the Reset Companion can help you apply them.

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