What to Know About Chronic Migraine and Botox

In the U.S., an estimated 40 million people experience migraines—but only about 20 million have been diagnosed, and of those, 84% say they want better treatments.

Andrew Blumenfeld, MD, a Cedars-Sinai neurologist, is a headache expert who pioneered the use of Botox to treat chronic migraine and trains physicians across the world on the injection technique. Blumenfeld authored the studies that define how Botox works to treat headaches—the toxin switches off pain fibers—and continues to research its effects.

Here, Blumenfeld explains everything you need to know about how Botox can treat this debilitating and underrecognized condition.

What is migraine, and who is most at risk?

Andrew Blumenfeld: Migraine is a genetic disease that more commonly affects women than men, at a rate of 3:1.

Migraine attacks are caused by a combination of genetic predisposition and environmental triggers (such as a change in the weather) or internal triggers (e.g., a hormonal change, such as the onset of perimenopause or menopause).

The location of the pain around the head, and its severity, can shift over a patient’s lifetime. But migraine is not just headache—it can also cause brain fog, excessive fatigue, dizziness and sensitivity to smell, light and noise. Rarely, patients experience visual changes or numbness in the arm or face, or speech difficulties.

How is migraine diagnosed?

AB: A primary care physician or a neurologist makes a diagnosis based on symptoms. Patients with migraine generally exhibit two or more of these four symptoms:

·      A one-sided throbbing headache of at least moderate severity

·      A headache that worsens with movement

·      Nausea with or without vomiting

·      Sensitivity to light and noise

The simplest way to determine if it's migraine: Does light, noise or movement worsen your headache? If it does, it's very likely a migraine.

How is migraine treated?

AB: Migraine is a progressive condition—every time you have an attack, it’s more likely you’ll have another one. So, treatment aims to decrease the number of attacks with preventive medicines, and also shorten the duration of each attack with acute medications.

Antidepressants, beta blockers and antiepileptic drugs are first-generation drugs used in migraine prevention. These tend to carry side effects, and studies show only one in five patients continues taking these drugs for over a year.

Medications called triptans are commonly prescribed as an acute “rescue” treatment taken at the onset of a migraine.
Botox was approved by the FDA as a preventive treatment for chronic migraine in 2010, and has become a well-established method. Botox is an injection containing a protein that temporarily blocks nerves that cause migraine.

In 2018, the FDA approved CGRP (Calcitonin Gene-Related Peptide) inhibitors as a preventive therapy. These medications target the chemical released in the brain during the migraine attack.

Who qualifies for treatment with Botox for migraines?

AB: To qualify for Botox, you must have chronic migraine, which means you have had headaches for more than 15 days out of the month, with at least eight days meeting the criteria for migraine, for three months.

Patients must also have tried two other medications for at least two months, and experienced less than a 50% reduction in headaches, or developed a side effect.

When I meet with a new patient, I explain we are going to be walking down a long road together to control the disease. We may need to try multiple different treatments over time. Some patients require multiple therapies; you could be on Botox and an CGRP inhibitor. We develop a partnership in our aim to get improved control over time.

What is the treatment process?

AB: At the appointment, we use a very small needle to make 31 shallow injections into nerves in the shoulders, neck, back of head, above the ears and forehead. Patients describe the injections like a little pinch or prick. It typically takes less than 15 minutes. We do this every 12 weeks.

How quickly does it work?

AB: Botox takes about 10 days to kick in. It may start to work after a day or two, but it builds up over time. With each treatment cycle, the effect is stronger. We always do a minimum of two treatments, because in the clinical trials, the results were only shown to be significant after the second cycle.

What are the side effects?

AB: In clinical trials, we found three main side effects, all of which are temporary: headache, neck pain and a droopy eyelid or eyebrow. Most of these side effects are the results of the injection technique—and after we published instruction papers and retrained doctors, the rates of eyelid drooping dropped from 3%-4% to 1%-2%.

Will Botox for migraines change a patient’s face?

AB: We don't necessarily need to inject into muscles that are giving you facial expressions. We can inject close to the hairline and maintain the horizontal lines across the forehead. Patients can still raise their eyebrows and wrinkle their foreheads—the one place it is difficult to avoid changing a person’s appearance is between the eyebrows—there are two large nerves that align with those muscles, so the “11” wrinkles potentially will diminish.

How long has Botox been in use for headaches?

AB: Botox was FDA approved in 1989 to treat spasm around the eye muscles, and I began prescribing it shortly after. Back then, and still today, we also use it for a condition called cervical dystonia, to correct muscle imbalances that cause neck and shoulder misalignment.

In the 1990s, Botox gained notoriety as a cosmetic treatment, and it was discovered, incidentally, to improve migraines. In 2000, I began clinical trials for Botox in my headache patients who didn’t respond to existing therapies, and it was very successful. The use of Botox decreased the use of other migraine treatments and the number of emergency room visits.

Through these studies, we identified the right type of patient—and also discovered the right places to inject.

What is your latest research on Botox for chronic migraines?

AB: In a 2025 study, we found that Botox for migraines was effective across race. There is racial diversity in migraine, and Black and Latino populations tend to be treated less often, especially with treatments like Botox. In this international trial, we showed the effects are equally positive regardless of race. Botox should be used much more broadly, and we need better access for populations that are not being treated currently.

In another study from this year, we found it is safe to use Botox for multiple indications if the dosage is kept to a certain amount, and when the treatments are performed around the same time. Botox is used for many different things: overactive bladder; post-stroke muscle spasms; excessive sweating and more. Some patients might require Botox to treat more than one condition.

Why are so many migraine patients undiagnosed? ‍

AB: There is a lot of stigma around migraine. People have viewed it as a women's disease, or a sign of weakness, and I think that stigma stems from the fact that many people only experience mild, tension-type headaches that get better when they go for a jog or move around. Some people don't realize how disabling the migraine attack is—the World Health Organization rates it the second most common cause of disability, behind chronic low back pain. It is a long-lasting condition that dramatically affects people’s productivity and lives. If you are suffering from headaches, talk to your doctor—we have well-tolerated treatments that help.