Health Canada has approved Botox® as preventive treatment for Chronic Migraine. It's also the only treatment for people with Chronic Migraine that can help prevent headaches and migraines before they even start.
What makes Botox® a different type of treatment? Unlike acute treatments, which are taken to treat a headache or migraine once it's already begun, Botox® prevents headaches and migraines before they even start. Botox® prevents on average 8 to 9 headache days and migraine/probable migraine days a month (vs 6 to 7 for placebo). And for people with Chronic Migraine - people who live with 15 or more headache days a month - that can make a big difference.
Botox® is a prescription medicine that is injected to prevent headaches in adults with chronic migraine who have 15 or more days each month with headache lasting 4 or more hours each day in people 18 years or older. It is not known whether Botox® is safe or effective to prevent headaches in patients with migraine who have 14 or fewer headache days each month (episodic migraine).
The discovery of Botox® for treatment of migraine was quite by accident. Several patients who were using Botox® for injection of wrinkles and also happened to have migraine. They reported improvement in headaches following injection into their brow and forehead muscles.
The mechanism of action involved in the alleviation of headache is not entirely clear. One possibility is that Botox® may decrease muscle contraction that may act as a trigger to migraine. Another theory is that Botox® may act on the brain chemicals called neurotransmitters and mediators that trigger pain and migraine.
Botox® is administered every 12 weeks using very fine needles. There are a total of 31 injection sites. Treatment takes about 15 minutes. The most common side effect is neck discomfort in 9% of patients. This discomfort, however, will resolve over time.
Problems swallowing, speaking, or breathing, due to weakening of associated muscles, can be severe and result in loss of life. You are at the highest risk if these problems are pre-existing before injection. Swallowing problems may last for several months.
Spread of toxin effects. The effect of botulinum toxin may affect areas away from the injection site and cause serious symptoms including: loss of strength and all-over muscle weakness, double vision, blurred vision and drooping eyelids, hoarseness or change or loss of voice, trouble saying words clearly, loss of bladder control, trouble breathing, trouble swallowing. Although these side effects are concerning, the safety margin of Botox® is about 100:1. It would take 100 times the therapeutic dose to poison someone with Botox®. The safety margin of other common medicines is around 20:1 (Aspirin and Tylenol).