The Scientific Evidence Behind Botox for Chronic Migraine Prevention

A Well-Tolerated, Safe Treatment for Chronic Migraine

Woman getting Botox injection
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Treatment of chronic migraines focuses on a combination of behavioral interventions, such as trigger avoidance, and pharmacological or drug treatments. While these measures work for some individuals, others are resistant or intolerant to these conventional methods of care. In these instances, one may consider more non-traditional therapies, like Botox.​

What Is Botox?

OnabotulinumtoxinA, known by the trade name Botox, is a toxin produced by the bacteria Clostridium botulinum and works by blocking nerve connections, which decreases muscle activity. Botox was approved by the FDA in 2010 for the prevention of chronic migraine.

Botox injection for your chronic migraine is a fast procedure, usually lasting 10 to 15 minutes, with numerous sites around the head and neck being injected. While there may be a small burning sensation associated with each injection, the discomfort is short-lived, and most people tolerate it just fine.

Does Botox Work?

The science behind Botox is promising, although not earth-shattering—studies suggest a small to moderate positive effect.

One study in Headache analyzed nearly 1300 patients with chronic migraine from the PREEMPT program. The PREEMPT program is a 56-week clinical trial investigating the use of Onabotulinumtoxin A as a preventive chronic migraine treatment.

In the PREEMPT study, participants were randomized to receive either injections in the head and neck muscles of Onabotulinumtoxin A versus a placebo injection every 12 weeks for 5 cycles (31 injections total). Of the participants, 35 percent had failed 3 oral preventive migraine therapies, whereas 65 percent had failed one.

They all had a diagnosis of chronic migraine. The participants and the Botox injectors were all blind to the treatment, meaning they did not know which injections they received (Botox versus placebo).

Results revealed that those who received the Onabotulinumtoxin A injections were more likely to have a reduction in the number of their headaches by the end of the study period (56 weeks). They were also more likely to report less "headache hours" on the days they had headaches.

In a separate study in The Journal of Headache and Pain, 254 patients with chronic migraine were injected with Onabotulinumtoxin A at the Hill Migraine Clinic in England. Over 90 percent of these participants had tried 3 preventive migraine treatments in the past and failed to respond. They underwent Botox injections in a similar protocol, as that accomplished in the PREEMPT study. Participants maintained a diary for at least thirty days prior to and after receiving the injections.

Results revealed that OnabotulinumtoxinA effectively reduced headache days and migraine days by at least 50 percent, and increased ​headache free days from baseline. The percentage of patients who achieved at least a 75 percent reduction in headache days and migraine days was 14 percent and 24 percent, respectively.

OnabotulinumtoxinA use also resulted in increased work productivity.​

Lastly, a study in JAMA, which was a large analysis on multiple randomized controlled trials that compared botulinum toxin A with placebo, also suggested a small migraine-Botox benefit. In this analysis, participants included those with different types of headaches like: episodic migraine, chronic tension-type headache, and chronic migraine headache.

Results suggested that Botox is beneficial in preventing chronic migraine, but not in episodic migraine or chronic tension-type headaches. It's important to know that the absolute reduction in the number of headaches per month in this study was found to be 2 to 3 days — so small, but significant for many.

 It's like having one weekend a month free of headaches.

What are the Downsides of Botox?:

For one, like any medication, there is the potential for side effects. In the JAMA study, these side effects were seen in more participants undergoing Botox injections than in the placebo group—that being said, they are still quite rare, but worth mentioning. 

A headache too may result from Botox injections—quite a paradox—but don't worry, this is usually short-lived. 

Another downside is that Botox can be quite expensive. Many insurance companies require extensive documentation that you have failed other preventive migraine therapies before covering Botox, and sometimes, even this does not work.

The Bottom Line

More scientific investigation into Botox would be useful. That being said, Botox appears to provide some benefit in preventing chronic migraines. It's good to note too that you can use Botox along with your other migraine medications—so it may give you that extra burst of relief you were not quite getting with your medication alone. 


Aurora SK, Winner P, Freeman MC, Spierings EL, Heiring JO, DeGryse RE et al. OnabotulinumtoxinA fHeadache Toolbox: Botox-A for Suppression of Chronic Migraine: Commonly Asked Questionsor Treatment of Chronic Migraine: Pooled Analyses of the 56-week PREEMPT Clinical Program. Headache. 2011 Oct;51(9):1358-73.

Jackson JL, Kuriyama A, Hayashino Y. Botulinum Toxin A for Prophylactic Treatment of Migraine and Tension Headaches in AdultsA Meta-analysis. JAMA. 2012;307(16):1736-1745.

Khalil M, Zafar HW, Quarshie V, Ahmed F. Prospective Analysis of the Use of OnabotulinumtoxinA (BOTOX) in the Treatment of Chronic Migraine; Real-Life Data in 254 Patients From Hull, UK. J Headache Pain. 2014 Sep 1;15:54.

Rothrock, J.S. (2012). American Headache Society. Headache Toolbox.