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.​

Understanding Botox

OnabotulinumtoxinA, known by the trade name Botox, is a toxin produced by the bacteria Clostridium botulinum. The toxin works by blocking the release of chemicals involved in nerve signaling, which decreases muscle activity and the activation of pain pathyways in the brain. 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 around 15 minutes, with numerous sites around the head and neck being injected. While there may be a small burning or pinprick sensation associated with each injection, the discomfort is short-lived, and most people tolerate it just fine.

Injection Sites for Botox Migraine Relief

When you undergo a Botox treatment, your neurologist or headache specialist will perform a total of 31 injections into seven key muscles of the head and neck. These seven areas of muscles include:

  • Corrugator: Located at the inner end of each eyebrow
  • Procerus: Located between the eyebrows
  • Frontalis: Located at the front of the head (forehead)
  • Temporalis: Located on each side of the skull (your muscle used for chewing)
  • Occipitalis: Located near the back of the skull
  • Cervical paraspinal muscle group: Located at the top and back of the neck surrounding the spine
  • Trapezius: Located at the upper back and back of the neck

This series of 31 injections across seven muscle areas is given once every 12 weeks, although, it can take up to six months (so more than one Botox treatment) to see the maximum benefit.

Research Behind Botox

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 five cycles (31 injections total). Of the participants, 35 percent had failed three 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 OnabotulinumtoxinA at the Hill Migraine Clinic in England. Over 90 percent of these participants had tried three 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 two to three days—so small, but significant for many. It's like having one weekend a month free of headaches.

Potential Botox Side Effects

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; all in all, though, 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. 

There are also some rare, but potentially serious and life-threatening side effects of Botox that require immediate medical attention. These side effects may occur hours to weeks after injection and include:

  • Problems swallowing, speaking or breathing
  • Signs of Botox spread—Loss of muscle strength, double vision, blurry vision and drooping eyelids, hoarseness, trouble saying words clearly, loss of bladder control, or trouble breathing or swallowing

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.

A Word From Verywell

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.