The Effectiveness of Botox Injections for Migraines

Botox (botulinum toxin A) is a prescription solution that can be injected in the facial and forehead muscles to treat and prevent migraines. Botox has been approved for the treatment of headaches that are present for 15 days a month or more. Most patients with chronic migraine headaches have pain that persists for 4 hours or more each day. Chronic migraine is a progressive, complex headache disorder that affects around 2% of the general population. This disabling, under treated neurological disorder is often difficult to treat.

What is Botulinum Toxin?

Botox is a neurotoxin produced by a bacteria called clostridium botulinum. These bacteria thrive in conditions without oxygen and can produce severe food poisoning (called botulism). Botulinum toxin paralyzes nerves by blocking the release of acetylcholine, which is a substance that blocks nerve signals to the muscles. It also prevents muscles from contracting, so a relaxation effect occurs. Botox is a poison only when it is ingested in the form of spoiled food.

The discovery of Botox for the treatment of migraines happened by accident. Botox is well known for its use as a wrinkle treatment. It is injected into muscles to relax and soothe wrinkles. It is also approved for the treatment of facial spasms, tics, and dystonia. Doctors began to notice several years ago that patients who received Botox injections reported improvement in their headaches.

How Does Botox Work?

The mechanism of action involving headache alleviation is not well understood. Experts theorize that Botox decreases muscle contractions that act to trigger migraine pain. Another theory involves brain chemicals (neurotransmitters) which act as mediators that trigger headache. The average dose of Botox is 100-200 units, and full effectiveness is seen around 2-3 weeks after the procedure. Injection series are spaced at 12-week intervals.

Several clinical trials have been completed showing the effectiveness of Botox for migraine therapy. In 20100, Botox was approved by the Food and Drug Administration (FDA) for the treatment of chronic migraines. Since there is no absorption to the gastrointestinal tract, Botox is a safe, effective migraine therapy.

How Well does Botox Work?

In a randomized clinical trial involving 1,384 participants, patients were divided into two groups: a Botox (treatment) group and a placebo (control) group. The researchers found that botulinum toxin A offered an effective treatment for chronic migraine, with much prophylactic benefit. Participants reported significant improvements, such as less head pain, overall improved quality of life, improved functioning, and reduced headache-related disability. In another similar study that was double-blind, subjects were evaluated at 28 days post-treatment. Researchers found that Botox was statistically superior to placebo regarding decrease in frequency of headaches. In addition. Botox was well-tolerated with little to no adverse side effects.

In a recent study, patients were treated with Botox every 3 months for a 6-month interval. They were first given 100 units into 20 different forehead sites, which distributed the medication among the muscles. With insufficient response, the patients’ doses were increased to 200 units to 40 different sites. These participants had an average of 24 headache days per month before treatment with Botox, and reported severe, disabling headaches 8 times each month. The majority of participants reported a good response, which was greater than 75% reduction in pain and frequency of headaches. In addition, the average number of visits to the emergency department reduced by 87%.


Aoki KR (2005). Review of a proposed mechanism for the antinociceptive action of botulin toxin type A. Neurotoxicology, 26:785–793.

Aurora SK, Dodick DW, Turkel CC, et al. (2010).Onabotulinumtoxina for treatment of chronic migraine: results from the double-blind, randomized, placebo-controlled phase of the preempt 1 trial. Cephalalgia, 30:793–803.

Diener HC, Dodick DW, Aurora SK, et al. (2010).Onabotulinumtoxina for treatment of chronic migraine: results from the double-blind, randomized, placebo-controlled phase of the preempt 2 trial. Cephalalgia, 30:804–14.

Dodick DW, Turkel CC, DeGryse RE, et al. (2010).OnabotulinumtoxinA for treatment of chronic migraine: pooled results from the double-blind, randomized, placebo-controlled phases of the PREEMPT clinical program. Headache, 14:921–936.

Oterino A, Ramon C, & Pascual J (2011). Experience with onabotulinumtoxinA (BOTOX) in chronic refractory migraine: focus on severe attacks. J Headache pain, 12(2), 235-238.