Botox is the only FDA-approved for chronic migraines, which means headache on 15 or more days a month. The more frequent the headaches, the better the patient does with Botox.
Botox is a form of botulinum toxin. When botulinum toxin is purified and used in tiny doses, it temporarily reduces muscle contractions for approximately 3 months.
Botox is injected around pain fibers that are involved in headaches. Botox enters the nerve endings and blocks the release of chemicals involved in pain transmission which prevents the activation of pain networks in the brain.
One treatment lasts for 10-12 weeks and with two to three Botox treatments the number of headache days can be reduced by approximately 50%.