Is Aimovig working? Judge it at month three, against your own baseline.
Aimovig can help within weeks, but the fair verdict comes at month three. Here's the timeline, the baseline method, and what to ask if it hasn't helped.
Is Aimovig working? The short answer
Aimovig (erenumab) often shows some effect in the first month, but the fair verdict comes at month three. That's the checkpoint the American Headache Society's consensus statement (2018, updated 2021) uses for monthly-dosed CGRP antibodies. The bar it sets: at least a 50% drop in headache days per month, or a clinically meaningful improvement on a migraine disability measure such as MIDAS or HIT-6.
So if you're three weeks in and unsure, you're early. Keep going.
And if you're at month three and still can't tell? The usual culprit is a missing baseline. Without a count of your migraine days before the first injection, there's nothing honest to hold month three up against, and memory after a hard quarter is a bad witness.
When does Aimovig start working?
Response to erenumab arrives along a curve, and the curve varies a lot from person to person. Some people feel a shift within days. A post hoc analysis of the pivotal trials (Schwedt and colleagues, The Journal of Headache and Pain, 2018) found erenumab pulling away from placebo as early as the first week of treatment.
Others get a slow build that only becomes obvious when three months sit side by side on a page. Neither pattern means the drug is or isn't for you. Here's how to read each stretch, and what to do with your log during it.
Where you are
What the evidence says
What to do with your log
Weeks 1 to 4
Some patients improve early; trial analyses found separation from placebo as early as week 1
Log every day, including good ones. Don't judge yet.
Months 1 to 2
Benefit often builds across monthly windows rather than all at once
Compare each month to your baseline, not to last month.
Month 3
AHS checkpoint for monthly CGRP antibodies: 50% or more fewer headache days, or meaningful MIDAS / HIT-6 improvement
Calculate your percent change and bring it to your neurologist.
Months 4 to 6
STRIVE measured its primary result over months 4 to 6, after the three-month mark
A partial response is a reason to discuss continuing or the 140 mg dose.
Sources: AHS consensus statement (Ailani et al., Headache 2021); Schwedt et al., J Headache Pain 2018; STRIVE (Goadsby et al., NEJM 2017).
What the Aimovig trials actually showed
In STRIVE, the six-month trial in episodic migraine (Goadsby et al., NEJM 2017), participants started at about 8.3 migraine days a month. Over months four to six, the 70 mg group dropped 3.2 days and the 140 mg group dropped 3.7. Placebo dropped 1.8.
That placebo number matters more than it looks. People on placebo improved too, partly because migraine frequency drifts on its own and people tend to enroll during a bad stretch. The chronic migraine trial (Tepper et al., Lancet Neurology 2017) showed the same effect louder: from a baseline around 18 days a month, both doses cut 6.6 days and placebo cut 4.2.
Your own month three carries that same noise. One quiet month proves very little. Several weeks of baseline compared against several weeks on treatment proves a lot more.
Episodic migraine. Goadsby et al., NEJM 2017.
How to track your baseline before month three
Count before you start. Ideally that's four weeks of daily logging before the first injection. Already mid-course? Reconstruct what you can from your calendar, pharmacy refill dates and missed workdays, and mark it as an estimate.
Define a migraine day once and never change it. Something like: any day with a migraine attack, or any day you took a migraine-specific acute medication. Write the definition down so month three uses the same rule as month zero.
Log the good days too. A blank day in a tracker is ambiguous. A logged headache-free day isn't.
Track acute medication days on their own line. Triptan and painkiller days are a second signal, and frequent use can feed medication-overuse headache, which muddies any preventive.
Note the after-phase. How long the fog, fatigue and light sensitivity hang on after the pain lifts changes how many usable days you actually get, even when the attack count barely moves.
At month three, do the math: baseline days minus month-three days, divided by baseline days. A hypothetical 10 days down to 5 is a 50% reduction.
One rule that makes the comparison honest
Use the same definition of a migraine day for your baseline and every month after. Changing the rule mid-course can manufacture or erase a 50% drop on paper.
Aimovig not working after three months: what to ask
"Not working" usually means one of three things, and each leads to a different conversation.
Partial response. Fewer days, but short of 50%. Ask whether to continue to month six, and whether moving from 70 mg to 140 mg makes sense. The US label starts at 70 mg monthly and notes some patients may benefit from 140 mg.
Little or no change. Ask about switching. Aimovig blocks the CGRP receptor, while fremanezumab, galcanezumab and eptinezumab bind the CGRP molecule itself, and the oral gepants atogepant and rimegepant both carry preventive approvals. Older preventives and, for chronic migraine, onabotulinumtoxinA remain options too. Which one fits is your neurologist's call, but it's a fair question to bring.
Something else is driving the days. Medication overuse, poor sleep, hormonal shifts or a new medication can all hold frequency up. Your log is how you spot it.
One practical note: insurers often want documented improvement before renewing prior authorization, so the same numbers do double duty.
Side effects and red flags
Aimovig's US label carries warnings for constipation with serious complications, new or worsening high blood pressure, and hypersensitivity reactions. Call your prescriber about severe or persistent constipation or a rise in blood pressure. Seek urgent care for a sudden worst-ever headache, weakness or numbness on one side, confusion, or trouble speaking.
A record beats a memory at month three
The month-three appointment goes better with a record than with recall. After a rough quarter, bad weeks blur together, and the after-phase almost never makes it into anyone's count.
Postdrome logs each attack as a continuous timeline, from the first warning sign through the fog and fatigue that follow, and keeps that data on your phone. When the appointment comes, you can export it and show your neurologist the number that matters: days lost, before and after.
A month where attacks drop but each one drags two days of fog behind it is a different month from one where both shrink. Only a log can tell them apart.
Start before your next injection, even mid-course. Four weeks of honest data beats three months of guessing.
Start your baseline before the next injection
Postdrome records each migraine on a continuous timeline, from the first warning through the after-phase most trackers skip, keeps the data on your phone, and lets you export it for your neurologist. Lifetime pricing, stated up front. That's what a month-three Aimovig check needs: a real baseline and a real comparison.
