If you stop taking Emgality, your migraines will likely increase gradually over the following months, but they probably won’t snap back to where they were before treatment. The drug has a 27-day half-life, meaning it lingers in your body for several months after your last injection and continues providing some protection during that time. No tapering is needed, and clinical trials show no evidence of withdrawal symptoms or rebound headaches.
How Quickly Migraines Return
Emgality doesn’t leave your system overnight. With a half-life of 27 days, it takes roughly five half-lives (about five months) for the drug to fully clear. During that window, you’ll still have some migraine protection, though it fades gradually.
In the EVOLVE-1 and EVOLVE-2 clinical trials, patients who stopped Emgality after six months of treatment were tracked for four additional months. Their monthly migraine days crept upward during that period but remained significantly lower than their pre-treatment levels. For example, in a Japanese study of episodic migraine patients treated for six months, average monthly migraine days rose from about 5.7 at the end of treatment to 6.2 four months later, compared to 8.8 before starting Emgality. Chronic migraine patients showed a similar pattern: monthly migraine days went from about 10.7 at the end of treatment to 11.2 during follow-up, versus 20.2 before treatment.
The longer you’ve been on Emgality, the more durable this carryover effect appears to be. Among patients treated for 18 months, only 47% experienced worsening after stopping, compared to 58% of those who stopped after just six months.
No Withdrawal or Rebound Effects
One of the biggest concerns people have about stopping a migraine preventive is rebound: a surge of headaches worse than what you started with. That doesn’t happen with Emgality. Across multiple randomized trials, researchers specifically looked for signs of withdrawal or rebound headaches and found none. The pattern was consistently a slow, gradual loss of benefit rather than any sudden worsening.
This is different from some older migraine preventives (certain antidepressants and blood pressure medications used off-label for migraine) that do require careful tapering. Because Emgality and other CGRP antibodies have such long half-lives, stopping abruptly is the standard approach. There’s no taper schedule and no need to wean off slowly.
What the Timeline Looks Like
Here’s roughly what to expect after your last injection:
- Weeks 1 through 4: You’ll likely feel little or no change. The drug is still at near-therapeutic levels.
- Months 2 and 3: Some people begin noticing a gradual uptick in migraine frequency or intensity as drug levels decline.
- Months 4 and 5: The drug is mostly cleared. By this point, you’ll have a clearer picture of your migraine pattern without treatment. Most people settle at a frequency somewhere between their on-treatment low and their original baseline.
Your individual timeline depends on how long you were on Emgality, how well it worked for you, and your underlying migraine biology. Some people find their migraines stay relatively well-controlled for months. Others notice a return sooner.
Why Some People Stay Better After Stopping
The fact that migraine days don’t fully return to pre-treatment levels is one of the more interesting findings from the clinical data. Researchers aren’t entirely sure why, but one theory is that sustained CGRP blockade may interrupt the cycle of chronic sensitization that drives frequent migraines. In other words, giving your nervous system a long break from repeated migraine attacks may reset some of the underlying processes that were making attacks more frequent.
This residual benefit was more pronounced in people who had been on treatment longer. Patients treated for 12 or 18 months retained more improvement after stopping than those treated for only 6 months, which supports the idea that a longer treatment course provides more lasting changes.
Switching to a Different Treatment
If you’re stopping Emgality because it isn’t working well enough or because of side effects, switching to a different CGRP antibody (such as erenumab or fremanezumab) is a reasonable option. In a real-world study of 54 patients who switched between CGRP antibodies, those who switched specifically because Emgality wasn’t effective enough saw significant reductions in headache days on the new medication. Side effects also shifted: in 12 cases, side effects from the first medication improved or resolved after switching, though 8 people developed new side effects on the replacement.
You don’t need a washout period between CGRP antibodies. Your doctor can start the new one at whatever point makes sense based on your injection schedule.
Planning for Pregnancy
Many people stop Emgality because they’re planning to become pregnant. There isn’t enough human data to know whether the drug is safe during pregnancy, so stopping before conception is the general recommendation. Given the 27-day half-life, it takes about five months for the drug to fully clear your system. If you’re planning ahead, that timeline is worth factoring in, though there’s no official FDA-specified washout period. A pregnancy exposure registry exists for people who were taking Emgality around the time of conception or during pregnancy.
Restarting Emgality Later
If your migraines return to a level that significantly affects your life, restarting Emgality is straightforward. The standard protocol is the same as when you first started: a loading dose of two injections, followed by one injection monthly. Most people who responded well the first time respond again upon restarting, though clinical trial data on restarting specifically is limited. Some insurers require documentation of migraine worsening before re-approving the medication, so keeping a headache diary after stopping can be useful if you think you might want to go back on it.